Olfactory Cues in Host Finding by Melittobia digitata (Hymenoptera: Eulophidae)

Chemical signals used by parasitoids to Þnd hosts often originate from the host, its habitat, or both, providing critical cues for locating hosts that are often cryptic or highly dispersed. MelittobiaWestwood are gregarious ectoparasitoids, which primarily attack Trypoxylon politum Say prepupae.HowMelittobia locates its host is unknown, but itmay involve host-related chemical signals. Therefore, this study focused on whether host location by Melittobia digitata Dahms is mediated by olfactory stimuli. In a small arena, which contained a choice of potential hosts [T. politum prepupa, Megachile rotundata (F.) prepupa, or Sarcophaga bullata (Parker) puparium], empty host pupal cases, or nest mudÑall of which were visually and physically isolated from the parasitoidÑMel. digitata successfully located host patches and spent signiÞcantly more time on those than on control (blank and dummy) patches. Results suggest that Mel. digitata females may be arrested by host-related chemicals.