CARBON ISOTOPIC SIGNATURES OF ELYTRA REFLECT LARVAL DIET IN LUPERINE ROOTWORMS (COLEOPTERA, CHRYSOMELIDAE)

Larval host associations in luperine rootworm beetles (Chrysomelidae), including the many pest species in the subtribes Diabroticina and Aul acophorina, 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, syste matic relationships, and pest management of luperine rootworms require knowledge of their larval host associations, techniques that enable i nference of larval host use from adult structures are needed. Using sp otted cucumber beetle, Diabrotica undecimpunctata howardi Barber, and striped cucumber beetle, Acalymma vittatum (F.), as model species, thi s study confirms that the stable carbon isotopic signature of adult el ytra (the ratio between C-13 and C-12 isotopes, expressed as delta(13) C) accurately reflects whether an individual consumed Cg plants throug hout its life, C-3 plants as a larva and C-4 plants as an adult, or C- 4 plants exclusively The study also demonstrates that, because the del ta(13)C of elytra is unaffected by time, easily accessible museum spec imens can be used for delta(13)C assays.