Synergistic attraction of kleptoparasitic flies, Desmometopa spp. (Diptera: Milichiidae) to the two vespid venom volatiles trans-conophthorin and N-(3-methylbutyl)acetamide
Director of Research Sterling International, Inc. Spokane Valley, Washington
Spiroacetals (including the commercially available E-7-methyl-1,6-dioxaspiro[4,5]decane, a.k.a. trans-conophthorin; tC) and the acetamides [especially N-(3-methylbutyl)acetamide; N3MBA] are two major groups of venom volatiles for most members of Vespidae. In the course of testing potential vespid attraction to these two major venom compounds, we caught “by accident” tremendous numbers of female milichiid flies (Diptera, Milichiidae),Desmometopanearctica Sabrosky and D. sordida (Fallén), on the Rescue® Wasp TrapStiks baited with the synthetic tC and N3MBA, even though no significant attractions to vespid wasps were shown at the dosages tested. The combination of tC and N3MBA attracted significantly more milichiids in a synergistic fashion than did the individual compounds. Our results suggest that females of these two kleptoparasitic milichiid flies use volatiles released from venom glands of the social vespids (yellowjackets, paper wasps and hornets) as kairomones to find disturbed, injured or freshly killed insects as their protein-rich foods for egg development/production.
