Host Preference and Utilization by Melittobia digitata (Hymenoptera: Eulophidae) in Relation to Mating Status

Host preferences of virgin and mated females of Melittobia digitata Dahms were compared in the laboratory using pupae of the flesh fly Neobellieria (=Sarcophaga) bullata (Parker) as hosts. When simultaneously offered two hosts, virgin females used only one of the hosts more often than mated females did. However, the unused second host developed to adulthood significantly less often than did controls, suggesting that the female stung and paralyzed it. Because virgin females lay only a few eggs that always develop into males which utilize very little of the host resource, this behavior seems adaptive in that potential hosts remain available, but developmentally arrested, for later full exploitation by the same female (now mated by her offspring). An additional implication of these results is that females can discriminate one flesh fly host from the other, and choose to avoid oviposition on both.