SEQUESTERED CUCURBITACINS AND PATHOGENICITY OF METARHIZIUM-ANISOPLIAE(MONILIALES, MONILIACEAE) ON SPOTTED CUCUMBER BEETLE EGGS AND LARVAE (COLEOPTERA, CHRYSOMELIDAE)

It has long been hypothesized that many luperine cucumber beetles ulti mately consume and sequester highly bitter cucurbitacin triterpenes to gain protection from predators and possibly parasitoids. Here we expa nd this protection hypothesis to include antibiotic protection against entomopathogens. Specifically, we examine the ability of cucurbitacin s sequestered in the eggs and larvae of Diabrotica undecimpunctata how ardi Barber, the spotted cucumber beetle, to reduce the pathogenicity of the entomopathogen Metarhizium anisopliae. Bitter and nonbitter egg s and larvae (those with and without sequestered cucurbitacin glycosid es) were exposed to 0, 10(3), 10(5), and 10(7) M. anisopliae conidia p er milliliter of distilled water. A significantly greater percentage o f both eggs and larvae containing cucurbitacins survived exposure to t he fungus, suggesting that the adaptive value of cucurbitacin pharmaco phagy in cucumber beetles includes an antibiotic benefit.