Cooperative Chewing in a Gregariously Developing Parasitoid Wasp, Melittobia digitata Dahms, Is Stimulated by Structural Cues and a Pheromone in Crude Venom Extract

Abstract

To disperse after mating, female Melittobia digitata Dahms (Hymenoptera: Eulophidae) tunnel through the walls of their host’s nest. We found that M. digitata use chemical and structural cues to identify locations for chewing exit holes. An experimental combination of milked venom and artificial pits on the inner surface of rearing containers elicited a stronger response than either stimulus alone. We suggest that the venom-associated cue may be a pheromone that facilitates mutual attraction, aggregation, and focused chewing, and that these behaviors may have arisen from behaviors associated with the initial stages of host attack. This apparently cooperative behavior promises insights into the possible evolutionary origins of components of eusocial behavior.