Additional diet of the parasitoids (Hymenoptera : Braconidae) and the parasitizing of the Elm Bark Beetle (Coleoptera : Scolytidae)

Supplementing the diet of Coeloides scolyticida, Dendrosoter protuberans an d Ecphylus silesiacus (Hymenoptera: Braconidae) with Parker's diet and the nectars of melliferous plants: Daucus carota L., Sinapis alba L. and Stachy s recta L. had a significant effect on longevity, reproduction, development al rate, and parasitizing of Scolytus scolytus (Fab.), Scolytus multistriat us (Marsh.) and Scolytus pygmaeus (Fab.) (Coleoptera: Scolytidae). These va lues were considerably lower for wasps fed with the nectar of Sinapis arven sis L. and Trifolium repens L. and the lowest for those without dietary add itives. Parker's diet had the most significant effect on the parasitoids and parasi tizing of the bark beetles. Nectar of S. recta and S. alba proved most suit able for C. scolyticida and D. protuberans, while E. silesiacus using the n ectar from D. carota flower significantly increased parasitizing of S. pygm aeus. T repens flowers were not a suitable additive for the diet of parasit oids. The parasitoids without additives in their diet had shorter lives, sh orter development, and were less effective in reducing host numbers. E. sil esiacus wasps had the longest development, and C. scolyticida the shortest. Generally, the parasitoids of the second generation had a slightly prolong ed development (1-2 days).