Host location by Melittobia digitata Dahms (Hymenoptera: Eulophidae), a larval parasitoid of mud daubers, Trypoxylon politum Say (Hymenoptera: Sphecidae)
Torres, Christian Sherley Araujo da Silva
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Signals helping parasitoids to find hosts often originate from the host and/or its habitats, providing cues for locating hosts that are often cryptic or highly dispersed. Melittobia are gregarious ectoparasitoids, which primarily attack Trypoxylon politum prepupae. How Melittobia locates its host is poorly known, but may involve host-related chemicals. This study investigated the roles of chemical cues and natal rearing effect in host location and recognition by M. digitata. In a small arena, which contained T. politum, Megachile rotundata, Neobelleiria bullata, empty cocoons, or nest mud, all isolated from the parasitoid, M. digitata spent significantly more time on host than on control patches. In olfactometer trials, M. digitata spent significantly more time in fields that contained hosts than on blank controls. Host cocoons elicited a positive response, but cues from nest mud and natal host fidelity were not supported. Results suggest that host-related chemicals act as arrestments for M. digitata females.