Notes on the biology and ecology of the parasitoids of the poplar clearwing moth. Paranthrene tabaniformis (Rott.) (Lep., Sesiidae) in Bulgaria. I. Apanteles evonymellae (Bouche, 1834) (Hym., Braconidae)

Aspects of the biology and ecology of Apanteles evonymellae (Bouche). a pal asitoid of the poplar clearwing moth. Paranthrene tabaniformis (Rott.). wer e studied during the period 1987-96. One-year-old poplar (Populus spp.) sho ots infested with P. tabaniformis larvae were collected during the winter m onths Lit ii localities in Bulgaria and examined in the field and laborator y. Apanteles evonymellae was recorded in all areas studied in Bulgaria. The mortality of P. tabaniformis caused by this parasitoid in various regions of Bulgaria varied from 2.4 to 35.4%: the average for the country was 17.3% . Laboratory observations showed that A. evonymellae is a solitary endopara sitoid of the poplar clearwing moth. It develops in early-stage (first- to fourth-instar) host larvae and overwinters as a larva in the host. Apantele s evonymellae is bivoltine, but only the second generation is associated wi th P. tabaniformis. In the field, adult parasitoids of first generation app ear in April about 1 month before the emergence of P. tabaniformis. The lon gevity of A. evonymellae adults: is a maximum of 6 days. Therefore, in the spring, A. evonymellae cannot attack neonate P. tabaniformis larvae and mus t develop in alternative hosts. Prior to their death the parasitized P. tab aniformis larvae construct conical structures. 'refuges' of frass and silk threads over the external openings of the larval galleries. Apanteles evony mellae pupates in these refuges after the host's death. This modified behav iour of the parasitized host larvae probably protects the pupae of A. evony mellae from hyperparasites and predators.