Co-Authors:
Mendel, Z., Department of Entomology, Agricultural Research Organization, Bet Dagan, 50250, Israel
Abstract:
Information on parasitoids of bark beetles infesting conifers and broadleaves is presented to show the relations between host and parasitoid size, and parasitoid sex ratios. Sticky traps were employed to determine the sex ratios of parasitoid species operating on beetle-infested material. A wide range in body length was found for most species. Females of Cerocephala eccoptogasteri Masi, Cheiropachus quadrum Febr., Eurytoma morio Boheman, Heydenia pretiosa Forster, Metacolus unifasciatus Forster, Rhaphitelus maculatus Walker and Roptrocerus xylophagorum (Ratz.) were usually significantly longer than their males, whereas the males of all four Dendrosoter spp. were significantly longer than the females. Body lengths of the males and females were almost identical in Entedon ergias Walker and Ecphylus caudatus Rusch. The sex ratio varied markedly within most species; the mean ratio for 5 of them differed significantly from 1:1. The sex ratio of M. unifasciatus and E. morio was significantly related to host size. The sex-ratio of parasitoids trapped on sticky traps varied with time in relation to the phenology of the host beetle. Females were more numerous during the larvae development while males were more abundant between the pupal stage and emergence of the host. Male courtship behaviour of Dendrosoter caenopachoids Rusch., D. protuberans (Nees), M. unifasciatus and R. xylophagorum is described. The effect of host size, the diversity in sex ratios, and possible interaction between parasitoid size and sex-ratio are discussed. © 1986 Lavoisier Abonnements.
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חסימת אנימציה
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