Pheromone response and mating behavior in the consperse stink bug, Euschistus conspersus Uhler

The attraction of the consperse stink bug, Euschistus conspersus Uhler (Hemiptera: Pentatomidae), to synthetic sources of the aggregation pheromone component methyl E2, Z4-decadienoate was investigated. Pheromone lures attached directly to common mullein, Verbascum thapsus L., demonstrated that these "baited" plants attracted significantly more E. conspersus than unbaited plants. Both reproductive and reproductively diapausing males and females were attracted to pheromone-baited plants in equal numbers. Response of adults peaked in the early hours of the scotophase, at approximately 2100h. Peak mating occurred at 2300h, with approximately 78.5% of the insects in the aggregation mating at this time. Aggregations dispersed to 30% of their maximums by dawn the following day on pheromone-baited plants. A laboratory analysis of feeding periodicity indicated that although feeding occurred throughout the 24-h observation period, the overall percentage of feeding insects was significantly higher during the scotophase. There were no differences between feeding rates in males vs. females. Detailed investigation of aggregation and mating behavior was performed in the field and laboratory. Males were found to transfer a significant percentage of their body mass during the initial mating. Mating reduced male longevity by 37.8% but had no significant effect on female longevity. Individual mate choice experiments demonstrated no preference by either sex based on weight. However, previous experience affected mate choice in both sexes: males were more likely to mate with virgin females, while females were more likely to mate with experienced males. Analysis of mating patterns in caged aggregations revealed that heavy males and light females mated more frequently than their respective counterparts. There was no evidence of assortative mating within aggregations based on size or experience. Rearing of parasitoids from adult E. conspersus confirmed the presence of two tachinid species, Gymnosoma filiola Loew and Gymnoclytia occidentalis Townsend. Three species of scelionid wasp were reared from fresh egg masses placed on mullein plants with Trissolcus utahensis (Ashmead) being the most common species. Bucket traps baited with the male-produced pheromone component captured significantly more G. occidentalis than unbaited controls, suggesting that this compound may act as a host-finding kairomone.