International Plant Resistance
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is not to be used in any form without the
consent of the specific author(s).
Edited by C. Michael Smith, Professor, and John C. Reese, Professor, Department of Entomology, Kansas State University, Manhattan, Kansas. Clerical assistance by Evelyn Kennedy.
Welcome from the Department of Entomology at Kansas State University to volume 26 of the International Plant Resistance to Insects Newsletter (IPRIN). We think the present format of the newsletter is helping plant resistance researchers continue to move into the world of 21st century digital communications. To all of you who continue to offer suggestions for further improvement, thank you very much.
For those of you reading the newsletter for the first time, we welcome your comments and contributions. If you wish to contribute items to future newsletters, they should be Word or WordPerfect files of two pages or less of text in length (tables are not printed) and can be submitted as e-mail file attachments to firstname.lastname@example.org, or on 3.5" computer diskette to Evelyn Kennedy, Department of Entomology, Kansas State University, Manhattan, KS 66506-4004.
Other types of plant resistance to insects information continue to be accessible also. The KSU Plant Resistance to Pests listserv, established by Donna Schenck-Hamlin of the KSU Hale Library and now administered by John Reese (JREESE@OZNET.KSU.EDU), is intended for continuous information exchange among individuals globally interested in plant resistance to pests about professional meetings, conferences and research grants, as well as new research developments concerning plant resistance to arthropods and plant pathogens. To subscribe to the bulletin board, send an e-mail message to: <email@example.com>, with the subject line blank, and the message "SUB PRP firstname lastname."
Use the e-mail address <PRP@KSUVM.KSU.EDU>to send a message to the entire bulletin board group. Kansas State University plant resistance to insects information is available on the Worldwide Web at http://www.oznet.ksu.edu/dp_entm/welcome.htm. Items available include the Painter Reprint Collection, archive editions of IPRIN, and new this year links to related websites including the Crop Science Society of America, CGIAR (Consultative Group for International Agricultural Research), and the Technology ISB Monthly News Report. Information is also available on how to subscribe to Plant Breeding News.
Thank for your interest in the IPRIN 2000. Please send your suggestions for improvement to Mike Smith at firstname.lastname@example.org or Mike Smith, Department of Entomology, Kansas State University, Manhattan, KS 66506-4004. Your continued support, through contributions and/or financial assistance is much appreciated. Financial contributions may be sent to LaVona Francis, Department of Entomology, Kansas State University, Manhattan, KS 66506-4004, Attention IPRIN.
TABLE OF CONTENTS
14th Biennial International Plant Resistance to Insects Workshop
Graduate Student Symposium Abstracts
Items from the United States
Cervantes, Bosque-Perez, Eigenbrode
Kramer, Morgan, Throne, Bailey, Howard
Reese, Reeck, Kofoid, Nagaraj, Campbell, Ma, Girma, Zhang
Flinn, Smith, Malik, Liu, Harvey, Starkey, Gill, Brown-Gudeira, Tolmay, Havlickova, Holubec
Baker, Burd, Elliot, Greenstone, Kindler, Mornhinweg, Porter, Shufran, Webster, Chen.
Riedell and Hesler
Reinert, George, Mackay, Smith, Davis, Read, Busey, Engelke
Balasubramani, Muthukrishnan, Sadakathulla, Subramanian, Ramanathan
Bughio, Wilkins, Petrova, Pathan
14th Biennial Int'l Plant Resistance to Insects Workshop
Colorado State University -- Fort Collins, Co
Dates Held: 2/28/2000 to 3/2/2000
Abstracts of presentations made during the Graduate Student Symposium: Tri-Trophic Interactions and the Impact of Host Plant Resistance on Non-Target Organisms.
14th Biennial, INTERNATIONAL
PLANT RESISTANCE TO INSECTS WORKSHOP, Feb. 29 - Mar. 2, 2000, Fort Collins,
Organizer/Moderator: Kevin A. Shufran,
USDA-ARS, 1301 N. Western Rd., Stillwater, OK 74075
Bold lettering indicates the presenting
Tritrophic Interactions Among Tobacco
Budworm, (Heliothis virescens, Lepidoptera: Noctuidae), a Parasitoid
of the Budworm (Campoletis sonorensis, Hymenoptera: Ichneumonidae),
and Budworm Resistant Tobaccos.
T. R., Sorenson, C. E., Southern, P. S. Department of Entomology, North
Carolina State University, Raleigh, NC 27695
Effective management of pests of flue-cured
tobacco requires several components including insecticidal sprays, baits,
beneficial insects, and, recently, host-plant resistance. Understanding
interactions among different management strategies facilitates integration
of them into one system. Tobaccos CU 263 and CU 370 were bred for resistance
to the tobacco budworm (Heliothis virescens), which feeds upon the
developing vegetative growth of the plant. Campoletis sonorensis,
a significant natural enemy of the budworm larvae in North Carolina, parasitizes
the second and third instars of the budworm. Using the variety K 326 as
a susceptible standard, three experiments were performed to evaluate how
host-plant resistance may effect the parasitoid in the laboratory and field.
In the first experiment, H. virescens that had been reared on the
different tobaccos were offered for parasitization to C. sonorensis.
The larvae and any parasitoids that developed in them were maintained until
emergence of adult parasitoids or pupation of the larvae. Measurements
included weight of the budworms at parasitization, weight of the parasitoid
pupae in cocoons, weight of the parasitoid adults, length of time from
parasitization until parasitoid pupation, and length of time from parasitoid
pupation until adult parasitoid emergence. The only significant difference
in these parameters was a higher weight of pupae in cocoons from K 326
and CU 263 than CU 370 (the more resistant line). The objective of the
second experiment was to determine whether there were any differences in
parasitoid orientation to the host-plant in a wind tunnel assay. In addition
to the three tobaccos, there were three treatments. Plants were uninjured,
injured mechanically, or injured by budworm feeding with the larval budworm
present in the wind tunnel. While no differences existed among the tobaccos
within each treatment, the parasitoid females responded most to the plants
injured by the budworm feeding, then the mechanically injured plants, and
least to the uninjured tobacco. Finally, the interaction between resistant
host-plant and parasitoid was evaluated in the field. Rows of each tobacco
variety were planted in the field and infested with laboratory-reared H.
virescens of an appropriate size. After three or four days, the plants
were searched for surviving budworms. Recovered larvae were maintained
on artificial diet in an incubator. The experiment was repeated 6 times
over time. Significantly more budworms were recovered in K 326 than CU
370; recovery rates in CU 263 were similar to both other varieties. There
was no clear significant trend over time. Early in the season significantly
more of the recovered larvae had been parasitized than those recovered
later in the season. No differences in proportion of larvae parasitized
occurred among the varieties. Similarly, if total mortality is defined
as unrecovered budworms plus parasitized budworms, then significantly more
mortality occurred earlier in the season than later. Greater mortality
also occurred on the resistant tobaccos than K 326. Finally, significantly
more parasitized budworms from K 326 yielded adult parasitoids than the
resistant tobaccos. The lower percent emergence in the resistant varieties
may reflect a fitness cost of the lower pupal weight in cocoons in the
first experiment. While there may be a fitness cost to the parasitoid,
the second and third experiments demonstrate that parasitoid efficacy is
unhindered and total mortality of budworms may be enhanced in the resistant
Effects of plant morphological complexity on the efficacy and efficiency of Coccinella septempunctata L. as a predator of the pea aphid Acyrthosiphon pisum Harris. Ana Legrand and Pedro Barbosa. Department of Plant Science, 1376 Storrs Road, U-67, University of Connecticut, Storrs, CT 06269 and Department of Entomology, Plant Science Building, University of Maryland College Park, MD 20742.
Host plant resistance relies on both chemical and physical plant traits. At the same time as these traits deter or harm insect herbivores, they can also have an effect on insect natural enemies. Physical plant characters that have been shown to impact the effectiveness of insect natural enemies include non-glandular trichomes, surface waxes and the size and shape of plant organs and protective structures. Another physical character that could influence the interaction between a herbivore and its natural enemies is plant morphological complexity. Plant complexity could provide a physical refuge to the prey or could interfere with foraging activities of a natural enemy. Andow and Prokym (1990) and Lukianchuk and Smith (1997) showed that egg parasitism was reduced when wasps searched for hosts on complex rather than on simple surfaces. Thus, the objective of this research was to test the hypotheses that increased plant morphological complexity reduces the area search efficiency and predation efficacy of Coccinella septempunctata L. a predator of the pea aphid Acyrthosiphon pisum Harris. Essential to testing these hypotheses is the use of near-isogenic lines of the pea plant. The Normal, tl and aftl near-isogenic lines were selected because they represented changes in morphological complexity that could be ranked from low to high complexity. Further, the use of these genetic isolines allowed for the control, as much as possible, of non-morphological plant characters such as phytochemicals and surface waxes.
The first step was to establish how plant morphological complexity might influence the herbivore. Changes in plant morphology did not have a significant effect on pea aphid total fecundity or intrinsic rate of increase. Moreover, plant morphology did not affect the choice of settling location by the pea aphid. Therefore it is unlikely that changes in plant morphological complexity have indirect effects on the predator via the aphid prey. While there were no significant effects on the prey, plant morphological complexity had a significant effect on the foraging efficiency of the coccinellid. Plant complexity influenced the foraging time of the predator and as a consequence residence time was longest on the most complex leaves (aftl plants), regardless of aphid presence. Due to the localized movements within a small fraction of the most complex leaf, coccinellids had a significantly reduced area search efficiency. Although the predation efficacy of the beetle was not affected by the morphology of the plants, plant complexity had a significant effect on the degree of prey disturbance by the predator. More aphids dropped or moved from their original position when the predator searched the tl plants which were intermediate in complexity. The results from separate experiments showed that the predator achieves the highest area search efficiency on tl leaves. This might explain why the coccinellid disturbed more prey on this plant type. The results presented in this study support the notion that plant complexity can interfere with the foraging activity of an insect predator.
Andow, D.A. and D.R. Prokym. 1990. Plant structural complexity and host finding by a parasitoid. Oecologia 82: 162-165.
Lukianchuk, J. L. and S. M. Smith.1997.
Influence of plant structural complexity on the foraging success of
minutum: a comparison of search on artificial and foliage models. Entomologia
Experimentalis et Applicata 84: 221-228.
Tritrophic effects of volatile chemicals associated with induced resistance in solanaceous plants.Ahnya M. Redman, Jack C. Schultz, and James H. Tumlinson. Entomology Department, Pennsylvania State University, 501 Agricultural Sciences and Industries Bldg., University Park, PA 16802; Entomology Department, Pennsylvania State University, Pesticide Research Laboratory, University Park, PA 16802; and USDA- ARS, Center for Medical and Veterinary Entomology, 1700 SW 23rd Drive, Gainesville, FL 32608.
There has been a flurry of interest recently in tritrophic interactions and the potential use of herbivore-induced volatile compounds in agriculture. But, a critical question that has not been nswered is whether the release of these compounds actually benefits plants, and thus growers utilizing these chemicals for biological control, by reducing pest populations. This question is equally important to ecologists interested in whether damage-induced volatiles have evolved to protect plants from herbivore-damage. Laboratory demonstrations of parasitoid-attraction to volatiles abound, but nothing is known about the function of these compounds in nature. We attempted to determine if natural enemies were attracted to volatile compounds in the field, using two solanaceous plants, tomato and eastern black nightshade, as well as the herbivore Manduca sexta (Lepidoptera: Sphingidae). First, we measured parasitoid-recruitment to tomato plants induced with natural damage (imposed at night, with herbivores removed each morning); to plants induced with 5 mM jasmonic acid (JA), a natural plant elicitor, biweekly; to untreated plants; and to plants treated with the solvent used to dissolve JA. Plants were protected from background herbivory by hand-picking, and parasitoid-recruitment was measured by recruitment to sticky traps and by parasitism of sentinel M. sexta caterpillars confined in mesh bags near treated plants. Parasitism of sentinels was significantly elevated on the induced plants over the two controls, and sticky traps showed a similar pattern, indicating that plants, not larvae themselves, attracted parasitoids. Parasitioids included some unidentified tachinids (Diptera), but were primarily Cotesia congregata (Hymenoptera: Braconidae).
The following field season, another experiment was conducted, utilizing both nightshade and tomato, to ascertain whether the same pattern could be detected when plants were exposed to background herbivory in addition to our treatments, and also to compare the effect of M. sexta regurgitant with the other two means of inducing resistance in plants. Parasitism of sentinels was measured on tomato plants treated with natural damage, JA, M. sexta regurgitant, no damage, solvent, or mechanical damage (the control for regurgitant). Natural damage received the highest level of parasitism, followed by JA and regurgitant, and all three differed from untreated, solvent-treated, and mechanically damaged plants. Nightshade plants were subjected to the same treatments, except for regurgitant and mechanical damage. Natural damage elevated parasitism compared to untreated plants, and although JA increased parasitism somewhat as well, it did not differ from either of the two controls.
In addition, we found in a census of arthropods on the foliage of treated tomato plants, that the relative composition of three functional feeding guilds (natural enemies; herbivores; and miscellaneous arthropods, which were primarily nectar-feeders) differed between treatments. The relative proportions of natural enemies and miscellaneous arthropods were higher than expected on naturally damaged and JA-treated plants, and proportions of herbivores were lower.
Headspace-sampling of plants grown in a
greenhouse revealed increased levels of myrcene, á-terpinene, 2-carene,
â-phellandrene, caryophyllene, and á-humulene released by
plants treated with M. sexta damage v. untreated plants, as well
as slightly (but significantly) increased levels of these same compounds
by regurgitant-treated plants v. mechanically damaged plants.
Effect of Bt corn on the predator Orius insidiosus (Say). Mohammad A. Al-Deeb* (Presenter) and Gerald E. Wilde
Laboratory feeding studies were conducted to determine the effect of feeding Orius insidiosus nymphs on 1 day old European corn borer Ostrina nubilalis (Hbn) larvae which had ingested diet containing Bt toxins (Dipel ES). A commercial formulation of Bacillus thuringiensis subsp Kurstaki (Dipel ES) was incorporated into a meridic diet used to feed European corn borer larvae; they were then offered as food to Orius nymphs. Immediately after eclosion Orius adult sex was determined, body weight and length were measured, and developmental time was calculated. Another feeding study was conducted to determine the effect of Bt corn silk on immature mortality of O. insidiosus. Fresh corn silks of Bt and non-Bt corn plants were offered to Orius nymphs till they reached maturity. Mortality counts were made daily. Finally, visual counts of O.insidiosus were made on Bt and non-Bt corn at three locations in Kansas (Abilene, Clay Center 1, 2). Number of Orius nymphs and adults were recorded on 40 plants per location on 2 sampling dates.
There was no significant difference in
developmental time, body weight, body length of mature Orius, and
immature mortality of Orius when reared on ECB larvae fed a diet
containing Dipel ES. Orius nymphs feeding only on Bt and
non-Bt corn silk suffered 100% mortality. There was no significant
difference in immature mortality when Orius nymphs were fed a day
on Bt and non-Bt silk and the other day on corn earworm eggs.
Numbers of Orius adults and nymphs in Bt corn fields did
not significantly differ from those of non-Bt fields. Our results
suggest that Bt corn does not have a significant effect on the predator
Biotypic and genotypic variation of greenbug populations collected from non-cultivated grass hosts. James A Anstead, John D Burd, Kevin A Shufran
The greenbug is an important pest of small grains in sorghum in North America. Resistant varieties have been deployed to control greenbug damage, but biotypes able to overcome this resistance have continued to cause significant loses. Very little is known about the biotypic or genotypic makeup of greenbug populations on grass hosts. It is hypothesized that non-cultivated grasses serve as a reservoir of diversity in the greenbug and that greenbugs move locally from non-cultivated hosts to exploit crops. It is also hypothesized that greenbug biotypes are in fact host specific races that evolved on non-cultivated grasses.
Greenbugs collected from a number of non-cultivated hosts and nearby cultivated hosts were tested for virulence against standard differentials to determine their biotype. Biotypic diversity was then compared between the cultivated and non-cultivated hosts.
The COI gene has been used to elucidate the relationships between the known greenbug biotypes (Shufran et al. unpublished data). They were found to fall into 3 clades; the biotypes predominantly found on sorghum (C, E, I and K) and J formed a single clade; biotypes B and the Canada Wild Rye isolate formed a single clade; the New York isolate (a possible example of biotype A) and biotypes F and G formed a separate clade. Biotype H diverged completely separately to the rest of the biotypes and was the most divergent.
The genetic relationship amongst isolates
collected in this study were estimated by the same molecular phylogenetic
techniques. A dendogram, based on a 1kb section of the COI mtDNA gene,
and including sequence data from the laboratory biotype colonies and field
collected colonies was produced. The relationships between host, biotype
and genotype will be discussed.
"Plant Allocation to Secondary Defensive Compounds: Testing the Carbon/Nutrient Balance Hypothesis in Elevated CO2". Carlos E. Coviella (1,2) and John T. Trumble (1), (1)University of California Riverside (2)Universidad Nacional de Lujan, Argentina
Plant resistance to herbivorous insects
depends in part on plant allocation to defensive secondary compounds.
The Carbon/Nutrient Balance Hypothesis (CNB) predicts that, when grown
in elevated CO2, plants should allocate relatively more resources to carbon-based
defenses as compared to plants grown in ambient CO2 levels. On the
other hand, concentrations of nitrogen-based defenses should decline.
We tested the CNB using a system that allowed us to simultaneously assess
CO2 and nitrogen fertilization effects on plant total carbon and nitrogen,
allocation to carbon-based and nitrogen-based defenses, and relating these
results with potential impacts on herbivorous insects. We used transgenic
Bt cotton plants as well as a near isogenic line without the Bt gene, grown
in both ambient (370 L/L) and elevated (900 L/L) CO2 levels. We selected
a split-plot design with CO2 level as whole plots, and with a 2 x 2 factorial
for two levels of nitrogen fertilization and two levels of nitrogen-based
defenses. We measured the effects of both elevated CO2 and nitrogen
fertilization on total plant Carbon, and total plant Nitrogen. The
nitrogen-based compound (the Bt toxin) and the carbon-based compounds in
cotton (total phenolics, condensed tannins, and gossypol) were analyzed
and quantified. We also examined the response of the insect herbivore
Spodoptera exigua (Hbner) using foliar bioassays. The performance
of the CNB hypothesis and the biological significance of the observed changes
in plant resistance to insects are discussed.
Molecular Markers Linked to
(Homoptera: Aphididae) Biotype I Tolerance in Aegilops tauschii.
Michael Flinn1, C. Michael Smith1, John C. Reese1,
and Bikram Gill2
1Department of Entomology, Kansas State University, Manhattan, KS 66506-4004
2Department of Plant Pathology, Kansas State University, Manhattan, KS 66506-5502
New advances in molecular biology are being used to enhance the future development of insect resistant lines of wheat. In developing insect resistance molecular markers, the categories of resistance the marker identifies must be identified. Aegilops tauschii accession TA 1675 (resistant donor), 'Wichita' (susceptible wheat cultivar), and line 97-85-3 (resistant offspring), were investigated and the category of resistance determined in each. Antibiosis was determined by calculating and comparing the intrinsic rate of increase of aphid population on 'Wichita', TA1675, and 97-85-3. Antixenosis was determined by measuring the number of aphids moving to each line of wheat planted around the perimeter of a 12cm pot. TA1675 exhibited antixenosis, but this resistance was not passed on to 97-85-3. Comparisons of SPAD meter readings and proportional dry plant weights were used to determine tolerance in each line. TA1675 and 97-85-3 were found to be highly tolerant compared to 'Wichita'. This tolerance provides a unique opportunity for it to be combined with biocontrol techniques as effective alternatives to insecticides.
Preliminary evaluations indicate polymorphism
between 'Wichita', compared to TA1675 and 97-85-3 genomic DNA when amplified
by PCR with wheat microsatellite (WMS) 428, and primers developed from
the wheat resistance gene analog (RGA)1 gene and the barley chitinase
(Cht)1b gene. These putative linkages will be determined by genotypic
and phenotypic evaluation of F2 progeny from the cross TA1675
x 'Wichita'. When confirmed, these molecular markers will help wheat breeders,
geneticists, and entomologists quickly and efficiently screen segregating
wheat populations and new accessions of wheat for greenbug resistance.
Morphological and Molecular Quantification of the Hessian Fly/Wheat Interaction, Luke Gumaelius and Roger Ratcliffe, Department of Entomology, Purdue University, West Lafayette Indiana 47907
The Hessian Fly (HF), Mayetiola destructor (Say),has been a economically significant insect wheat pest since its introduction to the United States in the late 1700s, causing massive crop losses throughout wheat growing regions of the country. Cultural controls and the institution of intensive resistance breeding programs have reduced, but not eliminated crop loss. The fly's life cycle begins in the fall with the emergence of pupating adults. The short-lived adults mate, lay eggs and die within 2-3 days. Upon hatching, the first instar larvae crawl down the leaf surface into the growing point where a series of feeding sites are established. The feeding process causes localized cell permeability and stunting of the developing third leaf. The eventual effect of this feeding is a severely stunted main stem that gradually turns darker green. Uninfested tillers visually appear to be unaffected by main stem infestation. This phenotype often persists throughout the plant's life. Although stereotypic, the aforementioned phenotype is not absolute. To the contrary, HF associated phenotypes are highly variable due to abiotic and biotic mediation.
My research is aimed at quantifying the range of morphological and molecular effects associated with HF feeding. Specifically, I have investigated: protein titre and size, chlorophyll titer, photosystem health, amino acid ratios, sugar pool sizes, root structure and whole plant morphometrics. Maggot size, infesting number and subsequent growth rate have been coupled with the plant measurements. Together these measures will indicate the relative sink strength of the infesting maggots and a biomass conversion ratio. This study will provide a baseline for future studies involving mechanisms of resistance and resistance gene introgression.
Phylogenetic Relationships Among Greenbug Biotypes, Andrea B. Jensen, J. Spencer Johnston, and George L. Teetes, Dept. of Entomology, Texas A&M Univ., College Station, TX 77843
The family Poaceae, the grasses, comprises
90% of the world's food crops. Greenbug, Schizaphis graminum, infests
70 species in this family, including wheat, barley, and sorghum. Understanding
biotype development has application to sustainable production of sorghum,
small grains, and many other crops for which insect-resistant varieties
are available but resistance is periodically lost due to resistance-breaking
biotypes. Determining biotype relatedness among greenbugs contributes to
an understanding of pest-host plant relationships. Biotype relatedness
was determined by sequencing 640 bp from the mitochondrial cytochrome oxidase
II (COII) and 530 bp from the 16S ribosomal RNA (16S rRNA) subunits from
multiple individuals of each greenbug biotype. Sequence data is examined
as phylogenetic relationships (gene trees) using maximum parsimony. Gene
fragments from the COII and 16S rRNA subunits show congruence. Significant
diversity exists that gene trees are resolved and results are compared
to biotypes and biogeography.
Antibiosis and tolerance of Canadian spring wheats to cereal aphids, S.M. Migui, Department of Entomology, University of Manitoba, Winnipeg, Manitoba R3T 2N2
Cereal aphids are pests of adult, spring-sown
wheat plants in Canada. Previous research on resistance to cereal aphids
concentrated on young winter wheat plants. To initiate research on identification
and incorporation of resistance to aphids for Canadian wheats, the susceptibility
of young and adult plants were compared for commonly grown wheats and pest
aphids. Cultivars of three wheat classes were exposed to three aphid species,
Rhopalosiphum padi (L.), Schizaphis graminum (Rondani) and Sitobion
avenae (Fabricius). Antibiosis was measured as the change in aphid
biomass during infestation. For young and adult plants, antibiosis to aphids
was similar among wheat cultivars, but R. padi produced more biomass
on young plants and Sc. graminum and Si. avenae produced
more biomass on adult plants. The impact of the aphids on plants was measured
as differences in biomass between control and infested plants. Aphid infestation
reduced biomass production of young plants equally among cultivars, but
padi and Sc. graminum reduced biomass of all cultivars more
than Si. avenae. The foliage biomass of adult plants did
not differ between infested and control plants, although infestation greatly
reduced seed yield. Schizaphis graminum and Si. avenae
caused the greatest yield reduction for all cultivars, but some cultivars
were more tolerant than others. To compare tolerance levels for the three
aphids and two plant growth stages, specific impacts were estimated based
on a biomass conversion ratio (units of biomass lost by plants per unit
gained by aphids). The specific impacts ranged from 1.0 to 3.5 for young
and 3.3 to 20.7 for adult plants, with young plants more tolerant of aphids
than adult plants. Young wheat plants cannot be used as a model for antibiosis
or tolerance of adult plants for these aphids. Adult plants of some Canadian
cultivars are more tolerant to infestation by aphids than others.
Effect of leaf color on growth and development of armyworms in cotton, D. Jones1, G.O. Myers1, and B.R. Leonard2 1 Louisiana State University, Department of Agronomy, Baton Rouge, LA 70803, 2 Louisiana State University Agricultural Center, Macon Ridge Research Center, Winnsboro, LA 71295
In cotton, both the fall armyworm (Spodoptera
frugiperda) and the beet armyworm (Spodeptera exigua) aresporadic
but economically important pests. Traditional control measures rely on
the use of costly insecticides. Little research has been done on possible
host plant resistance mechanisms. In 1998 it was observed that cotton germplasm
expressing the red leaf color phenotype showed less foliar damage than
normal green leaf color genotypes. In 1999 studies were performed to assess
the effect of leaf color on armyworm growth and development. Fresh leaves
of closely related green and red cotton genotypes were placed in petri
dishes and infested with 2nd instar larvae of laboratory reared
cultures of both armyworm species. Larval mortality and weight gain were
recorded at 2 day intervals for a period of 12 days (or until pupation).
The possible utility of cotton leaf color as a host plant resistance mechanism
which functions by suppressing armyworm feeding and subsequent development
will be discussed.
Host Plant Preference and Performance of Bemisia argentifolii(Homoptera:Aleyrodidae) on poinsettia (Euphorbia pulchirrima) in relation to cultivar. Laura O. Petro and Richard A. Redak, Department of Entomology, University of California, Riverside, CA 92521, USA
We investigated the resistance qualities
of seven economically important red cultivars of poinsettias against its
major pest, the silverleaf whitefly, Bemisia argentifolii, Bellows
and Perring. Additionally, two cultivars selected on the basis of previous
adult preference studies (representing preferred and non-preferred) were
monitored for nymphal development and survivorship. After 6 d of exposure,
the cultivars "Red Velvet", "Supjibi", and "Pepride" were less preferred
as oviposition sites than the other 4 cultivars evaluated. "Peterstar"
was the most preferred host for ovipostion. After 21 days of exposure,
there were significantly fewer eggs and nymphs observed on "Pepride " and
"Red Velvet", and "Peterstar" again had significantly more eggs than the
other preferred cultivars. The "Success" and "Petoy" had a significantly
greater number of surviving nymphs than the other cultivars evaluated Total
numbers of all live stages observed were significantly lower on "Freedom
Red", "Red Velvet" and "Pepride". These latter cultivars demonstrated the
greatest potential for resistance against the silverleaf whitefly. Observed
plant morphology in addition to plant chemistry may explain the differences
in suitability among the poinsettia cultivars. The population dynamics
of silverleaf whiteflies on the most preferred and non-preferred poinsettia
hosts are represented as life tables. The wider implications of the mechanisms
of poinsettia resistance to whiteflies and future uses in integrated pest
management for greenhouse cropping systems will be discussed.
Potato Leafhopper Resistance in Glandular-haired Alfalfa: A Comparative Study, Floyd W. Shockley and Elaine A. Backus, Dept. of Entomology, 1-87 Agriculture Building, University of Missouri, Columbia, MO 65211
Comparisons were made among seven different
genotypes of glandular-haired alfalfa supplied by two different companies,
Cal/West Seeds and Forage Genetics, in order to: 1) determine the relative
resistance to hopperburn and the potato leafhopper, and 2) suggest possible
physiological mechanisms of that resistance. A bioassay was designed to
collect data on leafhopper mortality, number of excretory droplets (a gross
measure of feeding), settling on various plant parts, hopperburn symptoms
and severity, plant stunting under constant leafhopper pressure, and glandular
trichome density on stems. A second bioassay was developed that would determine
whether the physical presence of intact glandular trichomes changed the
responses of the leafhoppers. This bioassay involved removing the stem
glandular trichomes by rubbing them off with a Kleenex® tissue
and then infesting those plants with leafhoppers. Three of the seven genotypes
showed increased leafhopper settling with trichome removal, an expected
response if the resistance factor was located primarily in the trichomes.
However, four of the genotypes showed decreased leafhopper settling, suggesting
that the insects are responding to something other than physical contact
with the intact hairs. In order to ascertain whether morphological differences
in the glandular trichomes could explain variations in resistance, scanning
electron micrographs were taken of all of the genotypes. The trichomes
showed little difference from genotype to genotype; all appeared as a simple
ball atop a multicellular stalk. Further observational evidence to be discussed
suggests that the glandular trichomes produce some type of chemical, either
in the form of a volatile repellent or a contact deterrent. Future studies
will involve testing of some of these genotypes for volatility and contact
deterrency in the trichomes.
Induction of resistance in the black mustard Brassica nigra depends upon resistance trait and herbivore, Brian Traw Section of Ecology and Systematics, Corson Hall, Cornell University, Ithaca, NY 14853
Plant resistance occupies a continuum from
traits which are generally effective against most herbivores to traits
which are only effective against a small proportion of herbivores. On the
one end is allylglucosinolate, a chemical produced by the black mustard
nigra which deters generalists but actually attracts specialists to
oviposit and/or feed. On the other end are trichomes, which at high densities
deter both generalist and specialist herbivores of mustards. We are interested
in how the environment influences plant allocation of resources between
these two resistance traits. We compared leaf allylglucosinolate concentration
and trichome density in black mustard plants damaged by three different
herbivore species. Our primary question was whether these plant resistance
traits would be induced. We predicted that leaf trichome density would
be more likely than leaf allylglucosinolate concentration to be induced
by the herbivores, especially when the feeding was by a specialist herbivore,
because the production of allylglucosinolate might attract more specialists.
Two specialists Pieris rapae and Phyllotreta cruciferae and
one generalist Trichoplusia ni were each applied to 44 Brassica
nigra seedlings at the four leaf stage. We recorded herbivory and removed
the herbivores after 12 hours. Plants were later harvested after reaching
8, 10, 12, or 14 leaves (n_ per plant developmental stage). Pieris rapae
triggered a doubling of trichome density in subsequent leaves, whereas
neither Trichoplusia ni nor Phyllotreta cruciferae had a
significant effect on trichome density. The increase in leaf trichome density
was the result of more trichomes being produced, rather than a smaller
leaf area. Allylglucosinolate concentration was not induced by the three
herbivores. The specificity of the trichome induction to Pieris rapae
suggests that the plant receives a signal more specific than damage alone,
perhaps including some constituent of the saliva.
Chromosome Localization and Genetic Mapping of Russian Wheat Aphid Resistance Genes Dn1, Dn2, and Dn5i in Wheat Using Molecular Markers, Xuming Liu and C. Michael Smith, Department of Entomology; Bikram S. Gill,
Department of Plant Pathology, Kansas State University, Manhattan, KS 66506, USA; and Vicki Tolmay, Small Grain Institute, Private Bag, Bethlehem, Republic of South Africa
The Russian wheat aphid (RWA), Diuraphis noxia Mordvilko, is a serious economic pest of wheat and barley in the western United States and South Africa. Aphid resistant cultivars have proven to be a viable tactic for RWA management. Several dominant resistance genes have been identified in wheat, Triticum aestivum, germplasm, including Dn1 in PI 137739, Dn2 in PI 262660, and at least two resistance genes (Dn5i) in PI 294994. To determine the chromosome locations of these genes, genomic DNA of several near isogenic lines (BC 5+), as well as segregating F2 populations from crosses between the resistant PIs and four susceptible wheat cultivars, was amplified via PCR with molecular markers of known chromosome location. Results revealed that the locus for wheat microsatellite (WMS) 111, located on wheat chromosome 7DS (short arm), was tightly linked to Dn1, Dn2, and Dn5a. These results confirm that Dn1, Dn2, and Dn5a are tightly linked to each other, and provide new information about their location being 7DS, near the centromere, instead of as previously reported on chromosome 7DL (long arm). WMS 635 (near the distal end of 7DS) clearly marked the location of the previously suggested resistance gene Dn5b, and WMS 642 (located on 1DL) marked and identified a new gene Dn5c, which is located in a defense gene-rich region of wheat chromosome 1DL. Based on analyses of isogenic line data, the genetic distance between the Dn genes and their respectively linked WMS markers was estimated to be <3.2 cM [1 x 100 / 25]. Exact genetic linkage distances are being determined using F2 populations. These markers will prove very useful for the further study of RWA resistance genes and in marker-assisted breeding for aphid resistant wheat.
Key words: Russian wheat aphid, wheat,
molecular marker, Dn resistance genes
Isolation of the Nucleotide Binding Site Family of Resistance Gene Analogs from Alfalfa, J.C. Cordero and D.Z. Skinner, Kansas State University & USDA-ARS
Many disease resistance genes from different plant genera that confer strong resistance against a wide range of pathogens have been found to share sequence homology at specific regions. Furthermore, the NBS region of homology from the NBS-LRR group of R genes share conserved motifs - P-loop, Kinase-2, Kinase 3-a, and a putative membrane-spanning domain. The objective of this study was to isolate the NBS regions from Medicago sativa in order to evaluate the variability and to facilitate the future cloning of complete disease resistance genes.
PCR with degenerate primers designed from the P-Loop and the putative membrane-spanning domains was used to amplify a 500 bp fragment. The 500 bp product was cloned and sequence diversity was analyzed. Sequence analysis from 94 individual clones showed that fifteen significantly different types of NBS regions exist in alfalfa. Each possessed the conserved domains Kinase-2 and Kinase-3a, characteristic of the NBS region. The fifteen sequences were compared to the most similar NBS genes found with a BLAST search of the GenBank database.
Dendrogram analysis showed that three major
clusters of families exist in alfalfa that seem to have different evolutionary
origins. This suggests that further research evaluating the evolution of
disease resistance genes in alfalfa is possible. Additionally, the confirmed
existence of such a wide family of NBS regions in alfalfa might make it
possible to clone R genes using this approach in combination with Serial
Analysis of Gene Expression (SAGE) or differential display.
Department of Plant, Soil and Entomological Sciences1
University of Idaho
Moscow, ID 83844-2339
Daniel E. Cervantes, Nilsa A. Bosque-Perez and Sanford D. Eigenbrode
Hessian fly oviposition preference on winter wheats varying in surface waxes
Damage due to the Hessian fly, Mayetiola destructor (Say) (Diptera: Cecidomyiidae), has been increasing in northern Idaho for the last decade. The use of resistant varieties has been a principal control measure for this pest. Resistance to Hessian fly in wheat has relied on antibiosis, but in other parts of the USA this has resulted in the evolution of Hessian fly biotypes capable of overcoming resistance. Antixenosis, which focuses on non-preference by the ovipositing female, has the potential to reduce selection for new biotypes.
Free choice tests were conducted in the greenhouse to evaluate winter wheats for possible antixenosis to Hessian fly. Comparisons were made between Avalon and Avalon reduced wax, and in a separate experiment, between Virtue and Virtue reduced wax. Genotypes were tested separately at the seedling stage and the flag-leaf stage. There were no significant differences in number of eggs laid per female when the genotypes were tested at the seedling stage.
Significant differences in mean number of Hessian fly eggs were detected between the wheat genotypes when plants were tested at the flag-leaf stage. Female Hessian flies preferred reduced wax genotypes for oviposition compared to normal wax genotypes. Scanning electron microscopy of the winter wheats showed less crystal density on reduced wax compared to normal wheat genotypes. Gas chromatography was performed on the surface waxes in order to characterize the genotypes. Differences in surface wax components between normal and reduced wax genotypes were evident only at the flag-leaf stage. Nonacosane, hentriacontane, and octacosanol were greater in percentage of total constituents in the reduced wax genotypes, whereas these components were considerably lower in percentage in the normal wax genotypes. Some of the constituents identified may have influenced oviposition preference by the Hessian fly.
USDA-ARS North Central Regional
Plant Introduction Station
Richard L. Wilson and Sharon G. McClurg
During 1999, we evaluated 500 maize accessions (introductions) for resistance to leaf feeding by European corn borer (Ostrinia nubilalis (Hübner)). A 1 - 9 visual rating scale (1=no damage, 9=heavy damage) was used to evaluate the accessions in the field. Four accessions rated 3 or less (resistant). We also evaluated 509 accessions during 2000 and found 13 accessions to be resistant.
In 1999, we evaluated 189 maize accessions for resistance to stalk boring by European corn borer. Data were obtained by splitting stalks and measuring length of feeding tunnels. These data were compared to a resistant check inbred, B52. Fourteen accessions were as good as, or better than the resistant check. Data for 2000 are not available at this writing.
The Brassica collection is being field evaluated for cabbage aphid (Brevicoryne brassicae (L.)) resistance at Hermiston, Oregon (Gary Reed, Oregon State University, is cooperating on this project). A 1 - 5 visual rating scale (1=no damage, 5=heavy damage) was used to evaluate the accessions. During 1999, 24 of 500 accessions tested rated 2 or less (resistant) and in 2000, 31 of 581 accessions tested rated resistant.
Data from these evaluations will be made
available to the public via the Germplasm Resources Information Network
(GRIN). The web site to view this data is http://www.ars-grin.gov/npgs/or
you may contact our station directly via our web site, http://www.ars-grin.gov/nc7/.
Recent publications dealing with plant resistance to insects:
1 Wilson, R. L. and S. G. McClurg. 1999. Evaluation of sunflower germplasm for resistance to sunflower moth. Abs. Submitted Papers, N. Cent. Br., Entomol. Soc. Am. 54, 16.
2 Binder, B. F., J. C. Robbins, R. L. Wilson, C. A. Abel, and P. N. Hinz. 1999. Effects of Peruvian maize extracts on growth, development, and fecundity of the European corn borer. J. Chem. Ecol. 25, 1281-1294.
3. Wilson, R. L. 1999. Acquisition and Maintenance of Resistant Germplasm. In: Handbook of Pest Management. (Ed: Ruberson, J. R.) Marcel Dekker, Inc., New York, 239-262.
4. Abel, C. A. and R. L. Wilson. 1999. Evaluation of 11 maize populations from Peru for mechanisms of resistance to leaf feeding by European corn borer. J. Kan. Entomol. Soc. 72, 149-159.
5. Abel, C. A., R. L. Wilson, B. R. Wiseman,
W. H. White, and F. M. Davis. 2000. Conventional resistance of experimental
maize lines to corn earworm (Lepidoptera: Noctuidae), fall armyworm (Lepidoptera:
Noctuidae), southwestern corn borer (Lepidoptera: Crambidae), and sugarcane
borer (Lepidoptera: Crambidae). J. Econ. Entomol. 93, 982-988.
1515 College Avenue
Manhattan, KS 66502
K.J. Kramer, T.D. Morgan, J.E. Throne, M. Bailey and J.A. Howard
Results of collaborative research between ARS-USDA (Manhattan, KS) and ProdiGene, Inc. (College Station, TX) demonstrated that a new type of transgenic corn (maize) is insect-resistant. This corn contains the protein avidin, which results in kernels that have nutritional resistance to many stored-product insects because avidin binds the essential vitamin biotin. Insects feeding on this corn develop a biotin deficiency that leads to delayed development and toxicity. Avidin is a rather unique biopesticide because it is a protein found in one of nature's most nutritious creations, the chicken egg. Avidin occurs in the transgenic grain at only a fraction of the level present in eggs. This is one of the very few new ideas for use of transgenic plant biotechnology for insect pest management and has exciting possibilities.
Kramer, K. J., Morgan, T. D., Throne, J.
E., Bailey, M. and Howard, J. A. 2000. Transgenic maize expressing avidin
is resistant to storage pests. Nature Biotech. 18, 670-674.
Department of Entomology
Kansas State University
Manhattan, KS 66506
Sorghum Tolerance to Greenbug Feeding Damage
John C. Reese, G. R. Reeck, Ken Kofoid, Nandi Nagaraj, Leslie R. Campbell, Runlin Z. Ma, and Melaku Girma, Yu Zhang
In order to decrease any possible selection pressure for yet more virulent biotypes of the greenbug, Schizaphis graminum (Rondani), we have focused our efforts on the development of sorghum germplasm that exhibits tolerance to greenbug feeding damage, rather than antibiosis or antixenosis. We have emphasized the reduction of chlorophyll loss due to greenbug feeding damage. A chlorophyll meter was utilized to nondestructively measure chlorophyll of areas fed upon four days by greenbugs. Four accessions that showed only low levels of resistance to biotype I were utilized in a recurrent selection scheme to make a large number of crosses. Selections were screened for tolerance and many promising ones were returned to the scheme, thus the label recurrent selection.
We are continuing to screen a group of 1,017 selections for tolerance to biotype I greenbugs, and then screen those tolerant selections for tolerance to biotype K. We have completed screening a total of 315 selections for tolerance to biotype K. Sixty-one selections from the most recent group lost significantly less chlorophyll than the susceptible check.
The damage response elicited by feeding greenbugs appears to be caused mainly by pectinases such as polygalacturonase via a two-step process involving the release of cell wall fragments. Pectinases from various sources, including greenbugs, caused significant chlorophyll losses in susceptible sorghum plants. Cell wall fragments released by the actions of pectinases on pectin from various sources, including sorghum, also caused significant reductions in chlorophyll.
In the area of molecular genetics of pectinases, Yu Zhang is completing his M. S. thesis, Comparative Studies on Pectin Methylesterases of Sitophilus oryzae, S. zeamais, and S. granarius.
We are just starting a project on the relationships between chlorophyll loss and photosynthetic capabilities. Preliminary experiments suggest that greenbug feeding activities actually elicit a very rapid and dramatic drop in photosynthetic rates.
Barbehenn, R. V., J. C. Reese, and K. S. Hagen. 1999. The food of insects. In, Ecological Entomology (Second Edition). C. B. Huffaker and A. P. Gutierrez (eds.). John Wiley and Sons. New York. Pp. 83-121.
Girma, M., K. D. Kofoid, and J. C. Reese. 1998. Sorghum germplasm tolerant to greenbug (Homoptera: Aphididae) feeding damage as measured by reduced chlorophyll loss. J. Kansas Entomol. Soc. 71: 108-115.
Ma, R. Z., J. C. Reese, W. C. Black IV, and P. Bramel-Cox. 1998. Chlorophyll loss in a greenbug-susceptible sorghum due to pectinases and pectin fragments. J. Kansas Entomol. Soc. 71: 51-60.
Reese, J. C., W. F. Tjallingii, M. van
Helden, and E. Prado. 2000. Waveform comparisons among AC and DC electronic
monitoring systems for aphid (Homoptera: Aphididae) feeding behavior. In,
Principles and Applications of Electronic Monitoring and Other Techniques
in the Study of Homopteran Feeding Behavior. G. P. Walker and E. A. Backus
(eds.). Thomas Say Publ. In Entomol.: Proceedings. Entomol. Soc. Am. Pp.
1Department of Entomology
2Department of Plant Pathology
3USDA/ARS & Department of Agronomy
Kansas State University, Manhattan, KS 66506
4Department of Entomology,
Kansas State University,
Agricultural Research Center - Hays, Hays, KS 67601
5Small Grain Institute, Bethlehem,
Republic of South Africa
6 Czech Research Institute of Crop Protection, Prague, Czech Republic
Michael Flinn1, C. Michael
Smith1, Renu Malik1, Xuming Liu1, Tom
Harvey4, Sharon Starkey1, Bikram Gill,2
Brown-Gudeira3, Vicki Tolmay5 Helena Havlickova6,
and Vojtech Holubec6
Microsatellite Markers Linked to Six Russian Wheat Aphid Resistance Genes in Wheat
Xuming Liu, C. Michael Smith, Bikram
Gill and Vicki Tolmay
The Russian wheat aphid (RWA), Diuraphis noxia Mordvilko, is a serious economic pest of wheat and barley in North America, South America, and South Africa. Using aphid resistant cultivars has proven to be a viable tactic for RWA management. Several dominant resistance genes have been identified in wheat, Triticum aestivum, including Dn1 in PI 137739, Dn2 in PI 262660, and at least three resistance genes (Dn5+) in PI 294994. The identification of RWA-resistant genes and the development of resistant cultivars may be accelerated through the use of molecular markers. DNA of wheat from near isogenic lines and segregating F2 populations was amplified with microsatellite primers via PCR.
Results revealed that the locus for wheat
microsatellite GWM111 (Xgwm111), located on wheat chromosome 7DS
(short arm), is tightly linked to Dn1, Dn2, and Dn5, as well
as Dnx in PI 220127. Segregation data indicate RWA resistance in
wheat PI 220127 is also conferred by a single dominant resistance gene
(Dnx). These results confirm that Dn1, Dn2, and Dn5
are tightly linked to each other, and provide new information about their
location being 7DS, near the centromere, instead of as previously reported
on 7DL. Xgwm635 (near the distal end of 7DS) clearly marked the
location of the previously suggested resistance gene in PI 294994, here
designated as Dn8. Xgwm642 (located on 1DL) marked and identified
another new gene Dn9, which is located in a defense gene-rich region
of wheat chromosome 1DL. The locations of markers and the genes linked
to them were confirmed by ditelosomic and nulli-tetrasomic analyses. Genetic
linkage maps of the above RWA resistance genes and markers have been constructed
for wheat chromosomes 1D and 7D.
Molecular Markers Linked to a New Gene for Wheat Curl Mite Resistance in Wheat
Renu Malik, C. Michael Smith, Tom Harvey,
Sharon Starkey, and Gina Brown-Gudeira
Over 200 molecular markers have been evaluated
to map the location of the gene(s) in the WGRC40 germplasm responsible
for resistance to the wheat curl mite, Aceria toschilla Keifer.
Initial phenotypic evaluations indicated that this resistance is expressed
by a dominant gene. However, preliminary genotypic results indicate that
resistance is expressed by the previously identified Cmc1 resistance
gene from Aegilops tauschii, as well as a new gene, also from
Ae. tauschii. Both appear to be located on the short arm of chromosome
Molecular Markers in Wheat Linked to Tolerance to Greenbug Feeding Damage
C. Michael Smith, Sharon Starkey, John
Reese and Gina Brown-Gudeira
Plants containing the greenbug resistance genes Gb3, Gb4, Gb5, and Gb6 were evaluated for tolerance to chlorophyll loss from greenbug feeding in SPAD index experiments. The SPAD indices of wheats containing the Gb3, Gb5, and Gb6 genes were significantly less than those of the susceptible cultivar 'Thunderbird'. SPAD indices of two uncharacterized biotype I resistance sources from Aegilops tauschii , WGRC 04 and KSU94U306, were intermediate in phenotypic response. The resistance of these sources appears to be controlled by genes expressing a category of resistance other than tolerance.
DNA isolated from 'Amigo' (Gb3) and
'Thunderbird' (Gb0) was amplified with wheat microsatellite (WMS)
primers with loci on chromosome 7D and evaluated for putative polymorphisms.
Preliminary results of these experiments indicated that WMS primers 44
& 111 (7DS) and 130 (7AS) all differentially amplified 'Amigo' and
'Thunderbird' DNA in such a way to reveal putative polymorphisms. WMS primers
with loci on chromosome 1A, specific to rye, were evaluated for putative
polymorphisms between DNA containing 'GRS 1201' (Gb6) and 'Thunderbird'.
Preliminary results of these experiments indicate that WMS primers 33 and
136 each differentially amplify the DNA of resistant and susceptible cultivars
in such a way to reveal putative polymorphisms.
Evaluation of Aegilops Germplasm with Multiple Aphid Resistance in Wheat
C. Michael Smith, Bikram Gill, Helena Havlickova, and Vojtech Holubec
Afterwards, 20 Aegilops species
from the Gene Bank Collection of RICP, all possessing some level of resistance
the bird cherry-oat aphid or the English grain aphid were evaluated for
resistance to the Russian wheat aphid and the greenbug (biotype I) at KSU.
tauschii accession 7096 was similar in level of greenbug resistance
to A. tauschii 1675, a standard greenbug resistant control in aphid
evaluations at KSU. Both A. tauschii accessions were significantly
less damaged than the susceptible variety 'Wichita'.Two Aegilops cylindrica
(4059 & 4062) and an
Aegilops markgrafi accession were highly
susceptible and similar to 'Wichita' in response to greenbug feeding. A.
neglecta accession (8052) was moderately resistant to Russian wheat
aphid and greenbug. Sixty-seven pest-resistant Aegilops
from the KSU Wheat Genetic Resource Center were evaluated for resistance
to bird cherry-oat aphid and accessions TA36, TA4, and TA 168 were highly
M. S. Thesis
A Molecular Marker Linked to Tolerance in Aegilops tauschii Accession 1675 to Greenbug, (Homoptera: Aphididae). Michael B. Flinn, Kansas State University, Manhattan, Kansas. 2000.
The greenbug is a serious aphid pest of wheat and sorghum throughout the world. Its ability to overcome both resistant plant cultivars and insecticides make it a serious problem to crop producers. Nevertheless, traditional plant breeding techniques to produce insect resistant cultivars are an economical and environmentally sound way of managing greenbugs in sorghum production.
The categories of resistance to greenbug, Schizaphis graminum (Rondani), biotype I, were determined in Aegilops tauschii (goatgrass) accession #1675 (Ae. tauschii 1675) (resistant donor parent), 'Wichita' (susceptible wheat parent), and an Ae. tauschii derived resistant offspring, line 97-85-3 ('A97-85-3'). Antibiosis was determined using the intrinsic rate of increase of populations of aphids confined to each of the three wheats. Neither parent nor the resistant progeny expressed antibiosis. Antixenosis was determined by allowing aphids a choice to feed on plants of each of the three wheats. Ae. tauschii 1675 exhibited antixenosis, but this resistance was not inherited and expressed in 'A97-85-3'. Comparisons of SPAD meter readings and proportional dry plant weight loss were used to determine tolerance to greenbug feeding. Ae. tauschii 1675 and 'A97-85-3' were highly tolerant compared to 'Wichita'.
DNA from segregating F2 populations
from the cross [Ae. tauschii accession 1675 x 'Wichita'] was isolated
and amplified using all known wheat microsatellite PCR primers and other
degenerate primers for the D genome of wheat. Segregation analyses showed
that microsatellite marker XGWM44 was linked to the Ae. tauschii
1675 greenbug resistance gene(s). The location of XGWM44 was confirmed
as being on the short arm of wheat chromosome 7D. A genetic linkage map
was constructed for XGWM44
Smith, C. M. 1998. Plant Resistance to Insects. In: Rechcigl, J. E. and Rechcigl, N. A. (Eds.) Biological and Biotechnological Control of Insects Pests. CRC Press LLC., Boca Raton, FL. pgs. 171-208.
Dhaliwal, G. S. , V. K. Dilwari, and C. M. Smith. 1999. Host Plant Defense Against Insects. In: Dhaliwal, G. S., and Arora, R. (Eds.). Environmental Stress in Crop Plants. Commonwealth Publishers, New Delhi. pp. 172-210.
Oppert, B., K. Hartzer, and C. M. Smith.
2000. Characterization of the digestive proteinases of Hypera postica
Gyllenhal (Coleoptera: Curculionidae). Trans. Kansas Acad. Sci.
Lui, X. M. , C. M. Smith, B. S. Gill, and V. Tolmay. 2000. Microsatellite markers linked to six Russian wheat aphid resistance genes in wheat. Theor. Appl. Genet. 98: (In Press).
On August 3, 2000, after 32 years of service, Dr. James A. Webster will retire from the USDA-ARS, Plant Science and Water Conservation Research Laboratory, Stillwater, Oklahoma.
Jim received his B.S. in Zoology and M.S. in Entomology from the University of Kentucky, and then went on to earn a Ph.D. in Entomology from Kansas State University in 1968. He immediately came to work for ARS in East Lansing, Michigan, working on the cereal leaf beetle plant resistance program. After the successful development and release of CLB-resistant wheat and barley germplasm lines, the ARS phase of the program was discontinued, and in 1981 Jim transferred to Stillwater to work primarily on plant resistance to cereal aphids in the Wheat and Other Cereal Crops Research Unit. From 1993 to 1999 he served as Research Leader for that Unit, as well as Laboratory Director for the Plant Science and Water Conservation Research Laboratory.
Jim is best known for his leadership role during the initial detection of the Russian wheat aphid in the United States. His background knowledge on the insect allowed ARS to immediately distribute information to U.S. researchers and extension personnel. It is estimated that this advance information cut a year off the time required to develop management strategies for this new pest. For this work, Jim was awarded the Entomological Society of America Recognition in Entomology Award for Outstanding Contributions to Agriculture for 1996.
Jim is an active member in the Entomological Society of America, and has held numerous offices and committee chair positions in the Southwestern Branch. He is also a member of the American Society of Agronomy, the Kansas (Central States) Entomological Society, and the Southwestern Entomological Society. He participates in activities of the International Plant Resistance to Insects group, the Hard Red Winter Wheat Improvement Committee, and the Western Coordinating Committee for "Integrated Management of Russian Wheat Aphid and Other Cereal Aphids." He was the ARS co-organizer for an international ARS/Oklahoma State University aphid symposium held in Stillwater in 1990. He also was invited to serve as an outside reviewer of the South African Russian Wheat Aphid Research Program by the South African Department of Agriculture. During his career he authored or co-authored over 150 articles and book chapters, and he co-edited the 1999 Thomas Say Publications in Entomology book "Economic, Environmental, and Social Benefits of Resistance in Field Crops."
Because many of the people who have worked with Jim over the years will be attending this year's ESA annual meeting in Montreal in December, plans are in the works for a nice reception there. Information on that can be obtained from Dave Porter (email@example.com). As part of that event, we will present him with a book of congratulatory and memory letters. These can be sent to Ruth Treat, USDA-ARS, 1301 N. Western Road, Stillwater, OK 74075, by November 15.
A small, informal reception by the Stillwater group is also planned for Jim's last day, August 3. Any of Jim's coworkers who happen to be in the vicinity that afternoon are certainly welcome to stop by for coffee and cake.
Plant Science Research Laboratory, USDA-ARS
1301 N. Western St.,
Stillwater, OK 74075-2714, USA
C.A. Baker, J.D. Burd, N.C. Elliot, M.H. Greenstone, S.D. Kindler, D.W. Mornhinweg, D.R. Porter, K.A. Shufran, J.A. Webster, and Y. Chen.
Russian wheat aphid, Diuraphis noxia (Mordvilko)
Efforts are ongoing to develop Russian wheat aphid (RWA)-resistant wheat germplasm. Advanced wheat lines derived from 13 different RWA resistance sources were planted for seed increase, evaluation, and purification in preparation for germplasm release; these include 61 hard white winter lines, 87 hard red winter lines, 36 hard red spring lines, 63 soft white spring lines, and 42 hard white spring lines. Topcrossed seed was screened for resistance to RWA, and resistant plants were transplanted to the greenhouse for increase and progeny testing. Homozygous RWA-resistant lines will be selected for germplasm release. Field evaluations of winter RWA-resistant wheat lines continue to be made in Stillwater.
Durum wheats maintained by USDA -ARS GRIN have been evaluated for resistance to RWA. Resistant plants were identified, rescued, and grown for seed increase. Purified selections will be reintroduced to the GRIN collection, and crosses will be made with agronomically acceptable durum wheats.
Development of resistant X resistant populations
continued in order to study genetic diversity of RWA resistance in wheat.
Genetic diversity studies are ongoing for all resistant lines to determine
if these lines carry different genes for resistance to RWA.
Efforts continue to develop adapted RWA-resistant germplasm lines for all barley producing areas of the U.S. 2,500 spring and 450 winter BC3F3/F4 barley observation lines were evaluated in Aberdeen, ID with the cooperation of Phil Bregitzer and Darrell Wesenberg, USDA-ARS, Aberdeen, ID and head/row selections made for further analysis in 2001 headrows/preliminary yield trials. These lines include 20 susceptible backgrounds and 25 resistant sources. Seventy lines were evaluated in preliminary yield trials and selections earmarked for advanced replicated yield trials in 2001. These lines included 7 susceptible backgrounds and 24 resistant sources. Approximately 16 lines were evaluated in replicated advanced yield trials in several locations Idaho and Colorado for potential release as adapted germplasm lines. These lines include 3 susceptible backgrounds and 3 resistant sources. Other lines developed in conjunction with Phil Bregitzer were also evaluated in advanced yield nurseries at several locations in Idaho, Colorado and Nebraska. Crossing still continued to bring more resistant sources into adapted barley backgrounds.
Development of genetic populations to study genetic diversity among all 109 RWA-resistant barley lines identified and selected at Stillwater continued.
Data analysis is ongoing from a study conducted
in 1998 and 1999 in Idaho and Colorado, with the cooperation of Phil Bregitzer
and Frank Peairs, to determine the affect of early and late RWA feeding
on malting quality of malting barley cultivars and adapted RWA-resistant
Greenbug, Schizaphis graminum (Rondani)
Greenbugs were a serious pest on winter wheat in the central Oklahoma wheat growing area (north of I-40) in autumn of 1999. Intensity of infestations appeared to increase as one headed north towards the Kansas border. Early planted fields appeared to suffer less damage than later-planted fields, suggesting that fields were colonized by greenbugs primarily from mid-September through mid-October. Seriously damaged fields first became evident in late-October. Autumn weather was mild and dry, making conditions ideal for greenbug population growth. The majority of winter wheat fields in central Oklahoma were treated with insecticide in autumn of 1999 (mostly during November). Greenbug populations in untreated fields in central Oklahoma declined during winter, primarily due to the activity of parasitoids. Parasitism levels by L. testaceipes exceeded 90% in some fields. Most such fields had probably already suffered economic damage.
Wheat fields in the Oklahoma panhandle also developed serious greenbug infestations, but they developed later than in central Oklahoma, peaking in January or February. This was the result of low parasitism levels and mild weather. Much of the wheat acreage in the panhandle was treated with insecticide during January and February, but we believe that a smaller proportion of fields were treated than in central Oklahoma. Parasitism levels increased from late January through February and greenbug populations in untreated fields eventually crashed as the result; however not before economic damage occurred. Greenbugs were sparse in southwestern Oklahoma (south of I-40). The bird cherry-oat aphid was present in fields throughout the state, but generally occurred at low levels.
A regional field study to assess the overwintering ability and the success of the greenbug to undergo sexual reproduction is now in its third year. Research locations include Brookings, SD, Hays and Manhattan, KS, Stillwater, OK, and Bushland, TX. Greenbugs have produced sexual morphs at all locations, and except for the Bushland site, eggs have been collected and successfully hatched. Future plans include studies to optimize the process of artificially generating the greenbug holocycle and improving egg-hatch success.
A molecular phylogenetic analysis based on the cytochrome oxidase I mitochondrial gene was conducted on all greenbug biotypes found in the United States (B, C, E, F, G, H, I, J and K). In addition, three unique isolates, one from a New York colony (NY) that has been in culture since 1959, another that was collected from Canada wild rye (CWR) in Oklahoma, and an isolate from Germany (EUR) were used in the analysis. Genetic distances among greenbug biotypes ranged from 0.08% to 6.17% difference in nucleotide substitutions. Phylogenetic analyses produced dendrograms revealing three clades; clade 1 contained the 'agricultural biotypes' commonly found on sorghum and wheat (C, E, I, K, plus J), clade 2 contained F, G, and NY, and clade 3 contained B, CWR, and EUR, which are rarely found on crops. Biotype H fell outside these clades and may represent another Schizaphis species. Greenbug biotypes are a mixture of genotypes belonging to three clades and likely have diverged as host-adapted races on wild grasses as opposed to resistant crop cultivars. Biotype, as defined for the greenbug, does not appear to have any evolutionary or taxonomic status.
Information was developed that sheds new
light on a theory of breeding plants with resistance to insects. Older,
classical concepts of resistance breeding have dictated that "pyramiding"
genes (combining more than one resistance gene) into a single wheat plant
provided durable protection to insect pests and thwarted the development
of new damaging biotypes. Experimental wheat germplasms were developed
using various combinations of resistance genes and subsequently tested
with an array of greenbug biotypes. Results of these experiments clearly
show that pyramiding resistance genes in wheat does not provide additional
protection against greenbug biotypes.
Rice root aphid, Rhopalosiphum rufiabdominalis (Sasaki)
An obscure aphid found on wheat in Oklahoma was identified as the rice root aphid. Rather high numbers of this aphid were found on wheat beginning in October and continued through the middle of January. During October this was the most numerous aphid found on wheat. The aphid feeds at the base of the wheat plant. It is believed the aphid can cause economic damage to wheat, although losses have apparently never been quantified. The rice root aphid may be a particularly important pest of cereals in the southern Great Plains (Susan Halbert personal communication), where in addition to direct feeding damage, it can also transmit barley yellow dwarf disease. Interspecies similarities between the bird cherry-oat aphid and the rice root aphid often lead to visual misidentification, and damage to cereals often attributed to the bird cherry-oat aphid may sometimes be caused by the rice root aphid. A key distinguishing feature is that the bird cherry-oat aphid has six antennal segments whereas the rice root aphid only has five antennal segments. Other, non-diagnostic characteristics can often be used to separate the species, including presence of dense setae on the antennal segments, and the slight differences in coloration.
James Anstead (Cambridge, UK) has completed
his MS degree at Oklahoma State University (Thesis: Genotypic and Biotypic
Diversity of Greenbug, Schizaphis graminum (Rondani), on Non-cultivated
Hays, D.B., D.R. Porter, J.A. Webster, and B.F. Carver. 1999. Feeding behavior of biotypes E and H greenbug (Homoptera: Aphididae) on previously infested near-isolines of barley. J. Econ. Entomol. 92:1223-1229.
Lukaszewski, A.J., D.R. Porter, E.F. Antonelli, and J. Dubcovsky. 2000. Registration of UCRBW98-1 and UCRBW98-2 wheat germplasms with leaf rust and greenbug resistance genes. Crop Sci. 40:590.
Porter, D.R. and J.A. Webster. 2000. Russian wheat aphid-induced protein alteration in wheat. Euphytica 111:199-203.
Porter, D.R., J.D. Burd, K.A. Shufran, and J.A. Webster. 2000. Efficacy of pyramiding greenbug (Homoptera: Aphididae) resistance genes in wheat. J. Econ. Entomol. (in press).
Webster, J.A. and D.R. Porter. 2000. Reactions of four aphid species on a Russian wheat aphid resistant wheat. Southwest. Entomol. (in press)
Webster, J.A. and D.R. Porter. 2000. Plant resistance components of two greenbug (Homoptera: Aphididae) resistant wheats. J. Econ. Entomol. 93:1000-1004.
Shufran, K.A., Burd, J.D., Anstead, J.A.,
and Lushai, G. 2000. Mitochondrial DNA sequence divergence among greenbug
(Homoptera: Aphididae) biotypes: evidence for host-adapted races. Insect
Molecular Biology 9:179-184.
Name: James Anstead Date of Degree: July, 2000
Institution: Oklahoma State University Location: Stillwater, Oklahoma
Title of Study: Genetic And Biotypic Diversity of Greenbug Schizaphis Graminum (Rondani) Populations on Non-Cultivated Hosts
Pages in Study: 103 Candidate for the Degree of Master of Science
Major Field: Entomology
Scope and Method of Study: The purpose of this study was to determine the biotypic and genetic diversity of Schizaphis graminum on non-cultivated hosts. Collections made from non-cultivated hosts were screened against resistant crop lines to determine their biotype. A 1043 base pair region of the mitochondrial DNA, cytochrome oxidase I gene was sequenced to measure genetic diversity. The evolutionary and taxonomic status of biotype was also investigated.
Findings and Conclusions: There was significant
biotypic diversity on non-cultivated grasses. We found biotypes E, I and
K on non-cultivated grasses but we also found biotype G at higher than
previously recorded densities. An isolate with a unique virulence profile
was also found (i.e. a new biotype). Our study indicates non-cultivated
grasses are a reservoir of biotypic diversity. This study supports previous
conclusions that biotype formation was not driven by the development of
resistant crop varieties. Biotypes, as defined in the greenbug (by virulence
against resistant hosts) do not appear to have any evolutionary and taxonomic
status. Rather this study confirms the presence of three genetically distinct
clades in S. graminum. The distances between clades indicate one
to two million years have passed since they had shared a common mitochondrial
ancestor. These clades are likely to represent host-adapted races, with
only one of the three containing greenbugs commonly found on crop hosts.
U.S. Department of Agriculture
Northern Grain Insects Research Laboratory
Crops and Entomology Research Unit
2923 Medary Avenue
Brookings, SD 57006
Nutrient Solution Nitrogen Form and Bird Cherry-Oat Aphid Resistance in Wheat
Walter E. Riedell and Louis S. Hesler
Bird cherry-oat aphids (Rhopalosiphum padi L.) are common insect pests of wheat (Triticum aestivum L.) in the northern Great Plains. Heavy spring infestations of seedling spring wheat can reduce yield by about 80 % while fall infestations in winter wheat can reduce yield from 20 to 75 %. The nutritional status of wheat crops modifies cereal aphid biology and life cycle and plays an important role in allowing plants to compensate for insect damage. Fungal, bacterial, and viral disease infestation severity and crop disease symptom intensity were shown to be strongly influenced by the form of N (NH4-N or NO3-N) provided to plants. It is not known if differences in fertilizer N form provided to wheat would impact plant resistance to bird cherry-oat aphids. The availability of specialized fertilizer products and the development of nitrification inhibitors that block the conversion of NH3 to NO3 in the soil provides reasons for reexamination of the relative merits of NH4 and NO3 nutrition especially with respect to potentially improving aphid resistance in small grains.
The research reported here examined the impact of nutrient solutions with different forms of N (either all NO3-N or all NH4-N) on aphid population growth and plant growth in wheat. The objectives of our growth chamber experiments were to determine if the form of nitrogen provided in plant nutrient solutions affected aphid population growth parameters or the ability of wheat to withstand infestation. Aphid population growth characteristics (development time, number of aphids produced, and intrinsic rate of increase) were not significantly affected by nutrient solution N form treatments. Plants grown with NH4-N nutrient solutions had significantly less shoot fresh weight. Aphid infestation also significantly reduced shoot fresh weight. There were no significant interactions between nutrient solution N form and aphid treatments for shoot fresh weight. Aphid treatment did not reduce root fresh weight in plants given NO3-N nutrient solution, but did in plants given NH4-N nutrient solution. Thus, while N form given to wheat plants had no effect on aphid population growth characteristics, plants given NH4-N nutrient solution showed less root growth than plants given the NO3-N nutrient solutions. The results of this study suggest that use of NH4-containing fertilizer and soil nitrification inhibitors likely would not improve wheat resistance to aphids.
Riedell, W.E. and L.S. Hesler. 2000. Nutrient solution nitrogen form and bird cherry-oat Aphid resistance in wheat. Cereal Res. Commun. Accepted for publication 19 April 2000
Texas A&M University Research &
17360 Coit Road
Dallas, TX 75252-6599
Ph: 972/231-5362 FAX: 972/952-9216
Lantana Lace Bug, Teleonemia scrupulosa Stal, resistance among Lantana Cultivars for the Landscape - James A. Reinert, Steve W. George, Wayne A. Mackay, Erin Smith & Tim D. Davis. Lantana lace bug, Teleonemia scrupulosa Stal, (Hemiptera: Tingidae) is a primary insect pest of lantana, a tender perennial landscape plant that is commonly grown across the Southern United States for its heat and drought tolerance. Most of the literature on T. scrupulosa refers to its potential use worldwide as a biocontrol agent for several Lantana spp. that were introduced as ornamental plants from their native North and South America and had become major weed pests. Twenty-eight cultivars of three lantana species [Lantana montevidensis (K. Spreng.) Briq., L. camara L. and L. hybrida] were evaluated for resistance to the lantana lace bug in replicated field plantings exposed to natural infestations. Lace bug populations began to develop in mid July 1996, and were dispersed across the replicates within 30 days. Populations of nymphs and adults were sampled bi-weekly from Sep. - Nov. 1996 (5 sample dates). Highest mean populations for the 5 sample dates were present on 'Patriot Desert Sunset' (40.3 nymphs and adults/3-leaf sample/plant), 'Pink Frolic' (20.6) and 'Patriot Sunburst' (19.4), with 19 of the cultivars exceeding 4 lace bugs per 3-leaf sample. Plants of 'Weeping White', 'White Lightning' and 'Weeping Lavender' were never observed to have any lace bugs on them throughout the test period and 'Imperial Purple', 'Patriot Rainbow' and 'Denholm Dwarf White' had means of 0.1 total lace bugs per sample and never exceeded more than 0.7 per sample. The Resistance Performance Index shows that the aforementioned cultivars and additionally, 'Radiation', 'Dallas Red', 'Gold Mound', 'New Gold' and 'Lemon Swirl' occurred either 9 or 10 (out of 10) times in the top statistical groupings. When cultivars are grouped and analyzed by species, L. montevidensis (four cultivars with a mean of 0.02 lace bugs/3 leaf sample) is highly resistant whereas, L. camara and L. hybrida (6.73 and 9.54, respectively) are susceptible to the lantana lace bug. All of the L. montevidensis have flower color of either white or purple. Cultivars were also separated by flower color for analysis. Cultivars with purple or white flower color (primarily L. montevidensis) had far fewer lantana lace bugs (means of 0.03 and 1.73, respectively) developing on them than did cultivars with other flower colors. Additionally, cultivars with either gold or red flowers and the aforementioned purple- or white-flowered cultivars had far fewer lace bugs than did cultivars with either orange/red, yellow or a bicolor of yellow with another color. It appears that cultivars with either yellow or yellow bicolor flowers are among the most susceptible to the lantana lace bug. These results indicate that within most flower colors or bicolors, there exists a range of resistance among the cultivars.
Host Resistance to White Grubs (Phyllophaga spp.) among Genotypes of Poa arachnifera X P. pratensis Hybrids - James A. Reinert & James C. Read. White grubs are annual pests of both the cool- and warm season turfgrasses in the U.S. A 3-yr-old replicated planting of two genotypes of Texas bluegrass, Poa arachnifera Torr., and five of its hybrids with Kentucky bluegrass, P. pratensis L., was evaluated for resistance to white grub damage. A field population of Phyllophaga spp. (prob. P. congrua LeConte) had established and was causing significant damage across the replicated plots. On 31 May 1996, a visual rating (scale of 1-9 (turf damage, 9 = most damage with loss of stand, yellowing and loss of root anchoring; 1 = no damage or loss of turf quality) of white grub damage to the grass in each turf plot was taken. Grass in each plot was visually examined for wilting and loss of stand and the leaves of 4 to 5 randomly selected plants within the plot were pinched and pulled to indicate potential root damage and loss of anchoring. Based upon these results from randomized planting in field plots exposed to natural Phyllophaga adult selection, it appears that the two Texas bluegrass selections, Syn1 and Syn2, and three Texas bluegrass X Kentucky bluegrass hybrids, TXKY-90-13-16, TXKY-90-13-8 and 'Reveille' (evaluated as TXKY-90-16-1), have considerable resistance to white grub damage. TXKY-90-15-6 and TXKY-92-35-1 are susceptible and sustained significant damage (ca. 4 ranking) and loss of stand.
Host Resistance to Tawny Mole Cricket, Scapteriscus vicinus, in Bermudagrass, Cynodon spp. - James A. Reinert & Philip Busey. Three species of Scapteriscus mole crickets were introduced to the southeastern USA and have become major pests of turfgrasses, especially bermudagrass, Cynodon spp. The objective of the study was to evaluate genetic resistance among vegetatively propagated Cynodon genotypes to damage by tawny mole cricket, S. vicinus Scudder (Orthoptera: Gryllotalpidae). Genotypes of bermudagrass, including commercial cultivars, were evaluated for their response to the tawny mole cricket, in field screen cages. Adult tawny mole crickets were introduced into replicated cages in which bermudagrass plants were planted. Cage sidewalls extended below the soil line and extended with a soil erosion fabric to a depth of 75 cm, to prevent migration of the highly mobile mole crickets. Damage estimates were based on visual ratings and relative reduction in clippings mass of harvested plants in inoculated cages compared with the same genotypes in adjacent noninfested cages. The four cage pairs, mole-cricket-infested and noninfested, thus represented the main plots of a split-plot experiment in four replications. Differences were observed (P < 0.05) in tawny mole cricket damage among 26 genotypes evaluated across two experiments. 'Tifdwarf', 'Tifgreen', 'Sunturf', 'Texturf-10' and 'Texturf-1F' were the most susceptible and sustained more tunneling and feeding damage than any of the other genotypes. All bermudagrass selections tested were damaged, but 'Ormond', FL-2400, PI-290659 and PI-291586 showed the least overall damage. Resistance scores (83 to 99) were high for each of these genotypes. 'Tifway' and 'FLoraTeX', were common to both studies, and each received similar intermediate damage and growth reduction ratings. Whereas, conflicting results were produced with Tifgreen and Sunturf, which were also common to both experiments. The field screen cages provided an excellent environment to evaluate plant materials against a highly mobile soil insect such as the tawny mole cricket.
Resistance in Zoysiagrass, Zoysia spp., to the Tropical Sod Webworm, Herpetogramma phaeopteralis, Guenee - James A. Reinert & M. C. Engelke. The tropical sod webworm, Herpetogramma phaeopteralis Guenee (Lepidoptera: Pyralidae) is a primary pest of turfgrass especially in the southern states of the USA and many islands of the Caribbean Archipelago. Twenty cultivars and genotypes of zoysiagrass, Zoysia spp., were evaluated for resistance to tropical sod webworm adult preference for oviposition and larval feeding. Adults expressed a preference among the zoysiagrass genotypes for egg deposition as expressed by the resulting larval feeding. 'Cavalier', DALZ8501 and JZ-1 exhibited high resistance (rankings < 7) with low feeding damage while 'Meyer' and DALZ8516 (ranking >1.5) sustained near complete defoliation. When neonate larvae were allowed to develop on each zoysiagrass in a no-choice experiment, a similar ranking was produced. Cavalier, DALZ8501, 'Korean Common' and 'El Toro' exhibited high resistance in the form of much smaller larvae (6.3-7.5 mg) at the 15-day evaluation. Conversely, larvae developing on 'Diamond', Meyer and DALZ8516 were significantly larger (36.4 to 41.0 mg). Additionally, larvae developing on the resistant Cavalier, Korean Common, El Toro and DALZ8501 required more than a week longer to reach pupation compared to larvae feeding on Diamond, Meyer and DALZ8516, which required only 19.1-19.7 days. Compared to the industry standard, Meyer (19 days), Cavalier required 12 days longer to pupation. During this period, larvae were much smaller, eating far less and they would be more vulnerable to predation. The highest mortality was recorded on Cavalier. In contrast, larvae feeding on the three most susceptible genotypes had an accumulated mortality of 6.7 to 13.4% at adult emergence.
Cultivar releases by Texas Agric. Exp. Stn.
Engelke, M. C., V. G. Lehman, K. B. Marcum, P. F. Colbaugh, J. A. Reinert, B. A. Ruemmele, & R. H. White. 1996. Release of 'Mariner' (Reg. No. CV-8, PI 599032) a creeping bentgrass with good salt tolerance.
Engelke, M. C., P. F. Colbaugh, J. A. Reinert, K. Marcum, R. H. White, B. A. Ruemmele & S. J. Morton. 1996. Release of 'Diamond' or DALZ8502 a dwarf type zoysiagrass.
Engelke, M. C., J. A. Reinert, P. F. Colbaugh, R. H. White, B. A. Ruemmele, K. Marcum & S. J. Morton. 1996. Release of 'Cavalier' or DALZ8507 a zoysiagrass with good water stress tolerance and good insect and disease resistance.
Engelke, M. C., R. H. White, P. F. Colbaugh, J. A. Reinert, K. Marcum, B. A. Ruemmele & S. J. Morton. 1996. Release of 'Crowne' or DALZ8512 a zoysiagrass with excellent water stress tolerance and good insect and disease resistance.
Engelke, M. C., R. H. White, P. F. Colbaugh, J. A. Reinert, K. Marcum, B. A. Ruemmele & S. J. Morton. 1996. Release of 'Palisades' or DALZ8514 a zoysiagrass with excellent water stress tolerance and good insect and disease resistance.
Read, J. C., J. A. Reinert, P. F. Colbaugh
& W. B. Knoop. 1999. Release of 'Reveille' bluegrass.
Agriculture and Agri-Food Canada
Potato Research Centre, P.O. Box 20280
Fredericton, New Brunswick, Canada, E3B 4Z7
Y. Pelletier & G. C. C. TAI
Accessions from seven wild Solanum species
were evaluated in the field for their resistance to the Colorado potato
beetle (Leptinotarsa decemlineata (Say)). The multivariate insect
population density data were analysed using factorial analysis. The factors
extracted corresponded to relevant phases of the life cycle of the insect
and provided information on the mode of resistance (antixenosis and antibiosis)
of the plant species. S. berthaultii, S. capsicibaccatum, S. jamesii,
S. pinnatisectum and S. trifidum demonstrated both antixenosis
and antibiosis but had different level of resistance. The mode of resistance
of S. polyadenium seems to be caused by an antibiotic effect and
the resistance of S. tarijense by an antixenotic effect. Genetic
variability and heritability of insect resistance trait within accession
was trivial or inconsistent for all Solanum species studied.
Tamilnadu 608 002
Lecturer In Entomology
Faculty of Agriculture
Greetings from India. I am new member to the PRP group and I wish to thank all the members for their patience to go through this mail. I am a Lecturer in Agricultural Entomology working at Annamalai University, Tamilnadu situated in the southern peninsula of India.
I have just completed my doctoral research on Host Plant Resistance in Tomato against fruit borer, Helicoverpa armigera. In the process, I have collected and screened around 320 exotic and indigenous/ native /tribal tomatoes and isolated five accessions which are resistant to the borer both under field and glasshouse conditions. I am planning to work on those selected accessions in depth and many other wild accessions, I hold, with reference to their mechanisms of resistance, future scope in breeding programmes and other related areas.
I wish to pursue my post-doctoral research in this venture and if any of the distinguished member is willing to utilize my services, I will much thankful to him. I request all the learned members to mail me their suggestions and help in this regard.
Hope to receive fruitful information from the members.
Tamil Nadu Rice Research Institute
Aduthurai - 612 101
Screening Rice Entries of AICRIP in ADVANCED Yield Trial for Resistance to Insect Pests of Rice
V. Balasubramani, S. Sadakathulla, M. Subramanian and S. Ramanathan
Under all India Co-ordinated Rice Improvement Programme (AICRIP), 183 and 178 advanced yield trial entries of rice were screened during 1997-98 and 1998-99 respectively, for their reaction to insect pests under natural conditions. Damage score was recorded as per Standard Evaluation System (SES) of IRRI, Philippines and AICRIP protocol. In 1997-98, out of 183 entries fourteen entries viz., IET 14829, IET 14833, IET 14834, IET 14806, IET 14807, IET 14867, IET 14350, IET 14359, EIT 14584, IET 14935, IET 14955, IET 14956, IET 14657, and IET 14338 were found to be resistant against gall midge (Orseolia oryzae) throughout the crop stand. In 1998-99, out of 178 entries, IET 15177, IET 15178 and IET 15179 against gall midge, IET 15742 and IET 15072 against yellow stem borer (Scirpophaga incertulus) and IET 16120 against rice leaf folder (Cnaphalocrosis medinalis) were found to be moderately resistant.
Varying Level of Natural Incidence of Rice Leaf Folder
V. Balasubramani, P. Muthukrishnan, S. Sadakathulla, M. Subramanian and S. Ramanathan
Cnaphalocrosis medinalis Guenee was observed in Tamil Nadu Rice Research Institute, Aduthurai, India during August-September 1999. Variation among different medium duration varieties was found with respect to leaf folder damage. Damage score was recorded as per Standard Evaluation System (SES) of IRRI, Philippines in 0-9 scale. Among the 24 medium duration varieties/cultures screened, seven (ADT 38, ADT 39, ADT 40, Improved white Ponni, AD 95319, Bhavani and TPS 3) were found to be resistant, seven (AD 94010, AD 92215, CO 46, MDU 4, IR 20, TRY-1 and Paiyur 1) scored moderately resistant reaction, three (AD 94016, ASD 19, MDU 3) were found to be moderately susceptible and seven (AD 90072, CO 43, CO 45, MDU 2, PY-1, Red Ponni and PTS 2) were found to be susceptible.
Reaction of Short and Medium Duration Rice Varieties Entries to Tetranychid mite Oligonychus oryzae
V. Balasubramani, P. Muthukrishnan, S. Sadakathulla, M. Subramanian and S. Ramanathan
Twenty-five short duration and twenty-four medium duration rice varieties and cultures under advanced stage of yield trials were screened for their reaction to rice mite Oligonychus oryzae under in vivo condition during Kuruvai 1999 season (June-July sowing). Mite damage score was done on 0-9 scale as per Sridharan et al., 1992 (APRINL 18:66). When the natural incidence was high, out of 25 short duration rice, three varieties (ADT 41, ASD 8 and IR 50) recorded score 1, nineteen (ADT 36, ADT 37, ADT 42, AD 95010, AD 95078, AD 95104, AD 95106, ADTRH 1, DRRH 1, Pro Agro 6201, PHB 71, ASD 16, ASD 17, ASD 18, IR 36, IR 64, IR 72, TKM 9, and MDU 5) recorded score 3 and three varieties (ADT 43, ASD 20, and IR 66) recorded score 5. Among the medium duration varieties, ten (Improved white Ponni, AD 95319, AD 94016, ASD 19, CO 43, Red Ponni, Bhavani, Paiyur 1, TPS 2 and TPS 3) recorded score 1, tweleve (ADT 38, ADT 39, ADT 40, AD 90072, AD 92215, CO 45, CO46, MDU 2, MDU 3, MDU 4, IR 20, and PY 1) recordedd score '3' and two (AD 94010 and TRY 1) recorded score 5, showing their resistant, moderately resistant and moderately susceptible nature respectively.
Reaction of Popular Varieties of Medium Duration Rice in Nursery to Rice Thrips Stenchaetothrips biformis
V. Balasubramani, P. Muthukrishnan, S. Sadakathulla, M. Subramanian and S. Ramanathan
Twenty-six medium duration rice varieties/cultures were screened under natural conditions, 20 days after sowing in the nursery during Thaladi season 1999 (Sept-Oct sowing). Reaction score of 0-9 scale was adopted as per Standard Evaluation System (SES) or IRRI, Philippines. Three varieties viz., ADT 39, ADT 40, and Improved white Ponni recorded 1 (resistant), three cultures (AD 92215, AD 90072, and AD 94016) and two varieties (Pondy 1 and Red Ponni) recorded score 3 (moderately resistant), six varieties (ADT 38, CO 43, CO46, MDU2, TRY1, and ASD 19) recorded score 5 (moderately susceptible), Bhavani and AD 94010 recorded score 7 (Susceptible) and nine varieties (CO 45, MDU3, MDU 4, IR 20, Paiyur 1, TPS 2, TPS 3, BPT 5204 and ADRH 8) and a culture (AD 95319) recorded score 9 (highly suscpetible).
Scoring of Medium Duration Rice Varieties Against Yellow Stem Borer Scirpophaga incertulus (Walker) Attack
V. Balasubramani, P. Muthukrishnan, S. Sadakathulla, M. Subramanian and S. Ramanathan
Twenty-one varieties and five cultures of medium duration rice were screened for their reaction against the yellow stem borer Scripophaga incertulus (Walker) under natural conditions, based on dead heart counts on 30, 50 DAT (Days After Transplanting) and white ear counts on 80 DAT, during Thaladi season 1999 (Sept-Oct sowing). Based on the mean score (0-9 scale as per SES of IRRI, Philippines) nine varieties and two cultures (ADT 38, ADT 40, CO 43, CO 45, MDU 3, Pondy 1, ASD 19, Red ponni, Bhavani, AD 95319 and AD 92215) were found to be resistant with score 1. Twelve of the total varieties/cultures (Improved white ponni, AD90072, AD94010, CO 46, MDU 2, MDU 4, IR 20, Trichy 1, Paiyur 1, TPS 2, TPS 3 and ADRH 8) stored score 3 revealing their moderately resistant reaction. Only there viz. ADT 39, AD94016, and BPT 5204 were found to be moderately susceptible with score '5'.
Screening Banana Germplasm for Resistance to Lacewing Bug Stephanitis typicus
V. Balasubramani, P. Sundararaju and H.P. Singh
A total of 278 accessions from the banana germplasm maintained at National Research Centre on Banana (NRCB), Tiruchirappalli were screened for their reaction to lacewing bug Stephanitis typicus under natural condition, 7-8 months after planting. Of them five accessions viz., Kalibale (0286), Malaivazhai (0290), Dole (0459), Gandevi (0370) and Chakkarakel (0093) were found to be free from the incidence of S. typicus. The remaining 273 accessions had infestation of S. typicus which ranged from 10-40 percent infested leaves.
Horticulture Research International,
Warwick, CV35 9EF,
P.R.Ellis and N.B. Kift
Studies continued on the high levels of resistance to the cabbage aphid, Brevicoryne brassicae discoveredin certain lines of Brassica fruticulosa (n=8). F1 and F2 families have been produced from crosses between selected individual plants representing the extremes of the range of resistance. These families have been evaluated in a controlled environment. Resistance was found to be quantitative, with no mendelian segregation ratios observed.
In an earlier report, the results of evaluating about 400 Brassica accessions against B. brassicae were presented. The most promising gene pool was found to be the kales. Four of the kale accessions were selected for breeding work. In order to study the genetics of resistance these kales were crossed with a double haploid line derived from the calabrese 'Marathon' and with the Brussels sprouts 'Oliver', which had been used a susceptible standard in all field, glasshouse and laboratory experiments. One of the objectives of the project was to 'bank' genes for resistance in a rapid cycling brassica genotype so that they could be exploited in future breeding programmes with different horticultural brassica crops. The rapid cycling Brassica oleracea CRGC 121 has been shown to be highly susceptible to B. brassicae and was considered to be a suitable recipient of genes for resistance. The four kales were therefore crossed with this rapid cycling accession. F1 and F2 families were produced in 1997 and 1998 from crosses between all four kales and the different brassicas described above. Progeny from three of the crosses were evaluated in 1999. The results indicated that resistance was multigenic, the response to selection was poor, the susceptible brassica genetic background significantly influenced resistant phenotype and environmental affects influenced the expression of resistance. Microspore culture will be used to produce double haploid lines which can be assessed more thoroughly in replicated experiments. This should make it possible to partition environmental and genetic components of resistance and to identify true-breeding resistant lines.
A project has begun to search for resistance in Arabidopsis thaliana to three important aphid pests, B. brassicae, cabbage aphid, Lipaphis erysimi, the mustard aphid and Myzus persicae, the peach-potato aphid. About 110 different Arabidopsis accessions have been obtained and a series of experiments designed to evaluate material. For both B. brassicae and M. persicae several different clones of aphid have been collected and used in preliminary experiments to identify the most vigorous ones for use in subsequent screening work. Antibiosis resistance has been identified to B. brassicae in 2 accessions, with some putative resistance to L. erysimi also being identified in a separate accession.
A UK MAFF-funded project on lettuce continued in 2000 to investigate the resistance to Myzus persicae in the lettuce variety 'Iceberg', a Batavian type of lettuce. Six clones of the aphid collected from different locations in the UK have been established at Wellesbourne. The performance of these clones on a susceptible lettuce variety, 'Saladin' has been compared. Antixenosis and antibiosis screening techniques have been developed for the evaluation of resistance. Preliminary laboratory experiments have confirmed that the Batavian 'Iceberg' variety possesses moderate levels of antibiosis resistance to aphid attack. It is planned to investigate the biological and genetical basis of this resistance and to determine the performance of inbreds produced in a single seed descent programme bred from a cross between susceptible and resistant lettuce material.
A review has been written on the resistance of carrot to carrot fly, Psila rosae (see below). The team continues to offer seed companies and other organisations a service for screening breeding lines for resistance to carrot fly, Psila rosae. A new carrot fly-resistant variety, 'Resistafly', was released by A.L. Tozer (seed company) in the spring of 2000 as a result of the collaboration with Horticulture Research International.
ELLIS, P.R. (1999). The identification and exploitation of resistance in carrots and wild Umbelliferae to the carrot fly, Psila rosae (F.). Integrated Pest Management Reviews4, 256-268.
ELLIS, P.R., PINK, D.A.C., BARBER, N.E., & MEAD, A. (1999). Identification of high levels of resistance to cabbage root fly, Delia radicum, in wild Brassica species. Euphytica 110, 207-214.
ELLIS, P.R., KIFT, N.B., PINK, D.A.C., JUKES, P.L., LYNN, J. & TATCHELL, G.M. (2000). Variation in resistance to the cabbage aphid (Brevicoryne brassicae) between and within wild and cultivated Brassica species. Genetic Resources and Crop Evolution 47, 395-401.
ELLIS, P.R., PINK, D.A.C., McCLEMENT, S.J., SAW, P.L. PHELPS, K., VICE, W.E. & KIFT, N.B. (2000). Identification of sources of resistance in lettuce to the lettuce root aphid, Pemphigus bursarius. Euphytica. (Submitted)
KIFT, N.B., PINK, D.A.C., ELLIS, P.R. & TATCHELL, G.M. (2000). The influence of genetic background on the use and manipulation of resistance to the cabbage aphid (Brevicoryne brassicae) in kale (Brassica oleracea var. acephala). Annals of Applied Biology (In press)
ELLIS, P.R. (1999). Breeding the fly-free carrot. Grower 131 (12), pp. 18 & 20.
COLLIER, R.H., TATCHELL, G.M., ELLIS, P.R., & PARKER, W.E. (1999). Strategies for the control of aphid pests of lettuce. IOBC/WPRS Bulletin 22, (5), 25-35.
ELLIS, P.R. & ESTER, A. (1999). Possible reasons for the decline in carrot fly (Psila rosae (F.) infestations in western Europe. IOBC/WPRS Bulletin 22, (5), 83-87.
KIFT, N.B., ELLIS, P.R. & SINGH, R. (1999). Interpretation of aphid performance data in quantifying resistance. IOBC/WPRS Bulletin 22, (10), 65-70.
ELLIS, P.R. (1999). Exploiting the resistance in carrots and wild umbelliferae to the carrot fly, Psila rosae (F.). IOBC/WPRS Bulletin 22, (10), 45-52.
ELLIS, P.R. & KIFT, N.B. (2000). The exploitation of plant resistance in controlling insect pests of vegetable crops. IOBC/WPRS Bulletin. (Submitted).
ELLIS, P.R. & DERRIDJ, S.
(1999) (Editors). Breeding for
Resistance to Insects and Mites. IOBC
Ecotoxicology Research Group
Department of Agricultural and Environmental Science
Newcastle University, Newcastle upon Tyne
NE1 7RU, UK
R.M. Wilkins, (Richard.Wilkins@ncl.ac.uk) Senior Lecturer & Supervisor; Fazalluah M. Bughio (Fazallullah.Bughio@newcastle.ac.uk); Miss A.S. Petrova (A.S. Petrova@ncl.ac.uk); Ovais S. Pathan (O.S.Pathan@ncl.ac.uk) Ecotoxicology Group, Department of Agricultural & Environmental Science, University of Newcastle, Newcastle upon Tyne, NE1 7RU, UK.
Inhibition of gut proteolytic enzymes of Tribolium castaneum (Hbst.) (Coleoptera: Tenebrionidae) by albumin proteins isolated from insect-resistant and susceptible rice flours.
Fazalullah M. Bughio and Richard M. Wilkins
Seeds, especially those of cereals contain large quantities of protein and are major source of dietary protein. However, some are extremely toxic to animals and insects. Albumin protein was extracted from two forms of rice grain (brown and milled) of Dawn and DR82 cultivars, which are resistant and susceptible respectively to the stored product insect Tribolium castaneum. The aqueous extract of each grain form was divided and part was heat-treated for 10 min at 80°C. The concentrations of both heat-treated and untreated proteins of Dawn cultivar were significantly higher than DR82 in brown and milled forms except in the unheated brown form of the cultivars. The heat-treated proteins of both forms of the grains were the most effective in inhibiting the proteolytic activity of the insect gut. The effects of the heat-treated and untreated proteins of the two forms of Dawn cultivar on the proteolytic activity of Tribolium castaneum were significantly higher than the forms and treatments of DR82 cultivar.
Brown planthopper Nilaparvata lugens as a stress factor in rice plants
Adelina Petrova and Richard M. Wilkins
Phloem sugars and free amino acids are known to influence the feeding behaviour of many phloem feeding homopteran pests. Brown planthopper (BPH) also has the ability to modify plant nutritional physiology. Heavy infestations of BPH on rice plants induce proteolysis and a 30-fold increase in levels of several amino acids (arginine, asparagine, lysine, proline, and tryptophan), whereas free sugars and moisture content decrease (Sogawa, 1971; Cagampang et al., 1974).
Three rice varieties have been chosen on the basis of resistance to the BPH, Rathu Heenati (resistant), Bg300 (medium), TN1 (susceptible), and they have been grown under two nitrogen regimes. The total amount of amino acids of 8- and 6-week old plants infested with BPH have been measured and compared to that of the control plants. The ninhydrin method has been used for the determination of the amino acids.
Mechanisms of plant resistance in crops to the leafworm Spodoptera littoralis: role of gut detoxifying enzymes
Ovais Safdar Pathan and Richard M. Wilkins
The cotton leafworm, Spodoptera littoralis (Boisd.) (Lepidoptera: Noctuidae) is an important polyphagous insect pest attacking a wide variety of crops in tropical and temperate areas of Africa, Asia and Europe. The choice and combination of the methods for control depend on the pest complex, infestation and the costs of implementation. Much control is achieved through integrated pest management including insecticides and mating disruption.
In contrast to monophagous pests, it is difficult to develop varietal resistance for polyphagous pests in the crops attacked. However, an understanding of the reasons for susceptibility of the various crops to attack may help in the development of resistant varieties. In the case of S. littoralis, dicotyledonous crops are preferred to monocots. An understanding of the mechanisms that contribute to this preference could have a role in improving crop resistance and biological control.
The objectives of this study were to compare
feeding on selected crops (maize, wheat, sunflower and cabbage) and the
consequential response from the insect in terms of detoxification activities.
Larvae were reared on the crops until the last instar and their weight
gains, food intake and cytochrome P450 enzymes (CYP1A1 and CYP2B1) activities
measured. Food consumption and CYP1A1 activity was low on wheat and maize.
In sunflower and cabbage both enzyme activities were significantly increased.
The role of these enzymes in the insect's response to the crops will be
discussed in terms of the food utilisation and in the comparison of the
Bughio, F. M., and R. M. Wilkins. 1997. Effect of rough rice cultivars on larval period and F1 emergence time of the red flour beetle Tribolium castaneum (Hbst.) and confused flour beetle Tribolium confusum (Duv.). International Plant Resistance to Insects Newsletter. 23: 55-56.
Bughio, F. M. and R. M. Wilkins. 1998. Influence of various types of flour of resistant and susceptible rice cultivars on biology of Tribolium species. International Plant Resistance to Insects Newsletter. 24: 11-12
Bughio, F. M., and R. M. Wilkins. 1998. Response of insecticide-resistant and susceptible strains of Tribolium castaneum to various types of grains flour of rice cultivars, pp. 4B-048. In Proceedings: 9th International Congress: Pesticide Chemistry, 2-7 August 1998, London. Royal Society of Chemistry, Cambridge, UK.
Bughio F. M., and R. M. Wilkins. 1999. Post-harvest pest management: resistant rice varieties in control of stored product insect pests, pp. 221-225. In Proceedings: 5th International Conference on Plant Protection in the Tropics, 15-18 March 1999, Kuala Lumpur, Malaysia. Malaysian Plant Protection Society (MAPPS).
Bughio F. M., and R. M. Wilkins. 2000. Influence of Malathion Resistance Status on Survival and Growth of Tribolium spp. (Coleoptera: Tenebrionidae), when Fed on Flour from Resistant and Susceptible Rice Cultivars. J. Econ. Entomol. In press.
Rauf, A., F. M. Bughio, and R. M. Wilkins.
1997. Insecticide resistance in Tribolium castaneum Herbst and
granarius L.: comparing residual film and topical application methods.
Tribolium Information Bull. 37: 163-169.
Fruit and Grape Research Centre
32 000 Cacak
Strawberry Resistance to the Aphid Chaetosiphon Fragaefolii (Cockerell) (Homoptera, Aphididae)
The paper presents the results of the studies
on the resistance of the strawberry Fragaria x ananassa Duchesne
and 652 hybrids of Fragaria ananassa x Fragaria chiloensis clone
Del Norte. Moderately resistant hybrids from the cross Senga Fructarina
x Del Norte (zf/1/94/96 and 2/11/95/97) and Dana x Del Norte (da/17/94/96)
were singled out on the basis of testing in the glasshouse and in the field.
Fifteen strawberry genotypes were used for studying survival and fertility
(a five-day test), longevity, fertility and production of honeydew on filter
paper with bromine cresol green in apterous parthenogenetic females. Significant
differences were recorded in all the evaluated parameters by genotypes,
with the lowest values obtained on the moderately resistant hybrids and
Del Norte. The population density of Chaetosiphon fragaefolii in
the field on the standard cultivars and moderately resistant hybrids shows
year-to-year variations. However, on the moderately resistant hybrids it
does not exceed 20% of the density recorded on the sensitive cultivars.
Strawberry genotype affects morphometric characters of parthenogenetic
apterous females. The smallest dimensions of the body and the apical segment
of the rostrum were observed in the females reared on Del Norte and moderately
resistant hybrids. Dimethoate and delthametrine are more toxic to the individuals
from the Ch. fragaefolii population reared on the moderately resistant
hybrid zf/1/94/96 compared to the population reared on the highly sensitive
selection ^a~anska Rana, particularly at LC90 level. The cross-section
of the leaf blade and leaf petiole in strawberry genotypes showing different
resistance to Ch. fragaefolii was studied by the paraffin method
and by staining it with safranine, crystal violet and light green SF. In
more resistant genotypes, besides thicker cell walls of the primary bark
collenchyma and a greater share of the collenchyma in relation to the parenchyma
in the primary bark, the main vascular bundles are encircled by a ring
of more intensely stained lignified cells forming a mechanical ring. This
stained reaction of cells to safranine and crystal violet also occurs in
smaller-sized vascular bundles, as well as in the leaf palisade tissue.
The tissue cross-sections in the sensitive genotypes reveal the predominance
of the green colour on the cellulose cell walls and protoplasts due to
the reaction to light green SF, whereas the stained reactions to safranine
and crystal violet are absent.
Key words: Chaetosiphon fragaefolii, Fragaria ananassa, Fragaria chiloensis, resistance, fertility, longevity, honeydew, morphometric ch