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Carbon isotopic signatures of elytra reflect larval diet in luperine rootworms (Coleoptera: Chrysomelidae)

Tallamy, D.W., Pesek, J.D.
Environmental entomology 1996 v.25 no.5 pp. 1167-1172
Acalymma vittatum, Diabrotica undecimpunctata howardi, adults, wings, carbon, stable isotopes, larvae, food plants, age, biochemical pathways, C4 plants, C3 plants
Larval host associations in luperine rootworm beetles (Chrysomelidae), including the many pest species in the subtribes Diabroticina and Aulacophorina, remain largely unknown because adults often feed on plant species and families other than those favored for larval development. Because important questions concerning the evolutionary origins, systematic relationships, and pest management of luperine rootworms require knowledge of their larval host associations, techniques that enable inference of larval host use from adult structures are needed. Using spotted cucumber beetle, Diabrotica undecimpunctata howardi Barber, and striped cucumber beetle, Acalymma vittatum (F.), as model species, this study confirms that the stable carbon isotopic signature of adult elytra (the ratio between 13C and 12C isotopes, expressed as delta 13C) accurately reflects whether an individual consumed C3 plants throughout its life, C3 plants as a larva and C4 plants as an adult, or C4 plants exclusively. The study also demonstrates that, because the delta 13C of elytra is unaffected by time, easily accessible museum specimens can be used for delta 13C assays.