Fredric V. Vencl

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Male competition in courtships of the firefly Photinus pyralis is intense. Morphometric analysis revealed that male size is variable, possibly exhibiting alternative body plans. We examined the outcomes of courtships to determine the proximate mechanisms of selection that may have led to male allometry. Two distinct selective events exist within mate(More)
Plant chemical defenses and escape from natural enemies have been postulated to select for dietary specialization in herbivorous insects. In field and laboratory bioassays, we evaluated the effectiveness of intact and chemically modified larval shield defenses of the generalist Chelymorpha alternans and the specialists Acromis sparsa and Stolas plagiata(More)
Larvae of the folivorous tortoise beetle, Plagiometriona clavata, carry shields formed from feces and exuviae above their bodies. We used an ecologically relevant predatory ant, Formica subsericea, in a bioassay to determine if shields functioned as simple barriers, as previous studies indicated, or whether they were chemical defenses. Shields were(More)
Larval insect herbivores feeding externally on leaves are vulnerable to numerous and varied enemies. Larvae of the Neotropical herbivore, Chelymorpha alternans (Chrysomelidae:Cassidinae), possess shields made of cast skins and feces, which can be aimed and waved at attacking enemies. Prior work with C. alternans feeding on Merremia umbellata(More)
Both adults and larvae of the sumac flea beetle, Blepharida rhois (Forster), are dietary specialists that feed on smooth sumac, Rhus glabra, on Long Island, NY. Instead of discarding their feces, B. rhois larvae retain it on their backs to form fecal 'shields'. We observed that ants attacking shielded larvae retreated and groomed vigorously, indicating the(More)
In response to intense enemy selection, immature folivorous insects have evolved elaborate, multi-trait defense arsenals. How enemies foster trait diversification and arsenal assembly depends on which selective mode they impose: whether different enemies select for the same defense or exert conflicting selection on a prey species. Theory has long supposed(More)
Whereas the “escape-and-radiate” plant-herbivore scenario predicts that reciprocating cycles of defense-counter defense foster the evolution of traits with increasing efficacy that accumulate during clade diversification, coevolutionary models of herbivore responses to their enemies remain unexplored. Quantitative information is scarce about how defensive(More)
Larvae of the leaf-feeding beetles Neolema sexpunctata and Lema trilinea carry feces on their backs that form shields. We used the generalist predatory ant, Formica subsericea, in a bioassay to determine whether shields were a physical barrier or functioned as a chemical defense. Fecal shields protected both species against ant attack. Larvae of both(More)
Ever since Darwin identified it as the force responsible for the evolution of exaggerated male characters, sexual selection has been the focus of research aimed at understanding the most bizarre and intriguing morphologies and behaviors in Nature. Two congeneric species in the firefly genus Photinus, P. pyralis and P. macdermotti, afford a unique(More)
FemalePhoturis versicolor fireflies attempt to capture males by responding to heterospecific flash patterns. A mating-dependent switch occurs which affects response timing and frequency of female flashes. We examined the switch using females of known age, mating status, and flash experience to assess how accurate mimicry is, what factors influence it, and(More)