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Department Seminars Coffee and Cookies
"Gut reactions--how insects eat plants"
May R. Berenbaum Division of Entomology
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Appearances notwithstanding, insects actually do have a few things in common with humans; among these is an appetite for, and dependence upon, plants as food. The ways in which insects and humans go about the business of eating plants, however, differ dramatically. Humans are spectacularly broad with respect to their intake of plant food; in a single day, a person can consume representatives of dozens of plant families. In contrast, insects are staggeringly narrow in their foodplant choices; over 90% of all herbivorous insects feed on 3 or fewer plant families and in many species larval development is completed on a single species. Insects also share with humans an ability to metabolize plant toxins via cytochrome P450 monooxygenases, heme-based enzymes that are responsible for a broad range of oxidative reactions. The dietary challenges imposed on insect P450s are fundamentally different from the dietary challenges imposed on human P450s. The biochemistry and molecular biology of cytochrome P450s in the swallowtail butterflies (Papilionidae), which feed primarily on furanocoumarin-containing plants in the carrot and citrus families, reveals striking differences in the structure and function of these enzymes in the life of these insects and provides insights into the process by which plant-feeding insects have come to be the most abundant multicellular organisms in terrestrial ecosystems today. *Please note date, time, and place changes.* |