Host-acceptance requirements of Melittobia digitata (Hymenoptera : Eulophidae), a parasitoid of mud dauber wasps

Behavioral studies were conducted of Melittobia digitata Dahms on Apis mell ifera (L.) pupae, pupa-shaped glass dummies, flat glass, and flat glass tre ated with honey bee extract to determine if females use shape or chemicals to identify a host for oviposition. Response to untreated flat glass was co nsistently lower than that to pupa-shaped glass. Females spent much more ti me on a pupa-shaped glass object than on a rectangular piece of glass. Time spent antennating on the bee pupa and on the glass pupa did not differ. Ho wever, antennation response to extract-treated flat glass and untreated fla t glass was lower than that on pupa-shaped glass. The addition of host extr act did not increase probing on flat glass. Wasps probed and antennated the glass dummy about as much as the bee pupa but did not respond much to the rectangular glass objects, indicating that shape plays a major role in the process of host acceptance. In these experiments, only bee pupae were accep ted for oviposition and never the glass objects. In further experiments, M. digitata was found to oviposit on Parafilm domes containing agar-based die t but not on domes containing only agar. Females responded to both shape an d nutritional content of the host but the surface chemical cues tested were unimportant to females considering an object for oviposition. (C) 2000 Aca demic Press.