Host-Acceptance Requirements of Melittobia digitata (Hymenoptera: Eulophidae), a Parasitoid of Mud Dauber Wasps

Behavioral studies were conducted of Melittobia digitata Dahms on Apis mellifera (L.) pupae, pupa-shaped glass dummies, flat glass, and flat glass treated with honey bee extract to determine if females use shape or chemicals to identify a host for oviposition. Response to untreated flat glass was consistently lower than that to pupa-shaped glass. Females spent much more time 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. However, antennation response to extract-treated flat glass and untreated flat glass was lower than that on pupa-shaped glass. The addition of host extract 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 accepted for oviposition and never the glass objects. In further experiments, M. digitata was found to oviposit on Parafilm domes containing agar-based diet but not on domes containing only agar. Females responded to both shape and nutritional content of the host but the surface chemical cues tested were unimportant to females considering an object for oviposition.