Determinants of Host Use in Tachinid Parasitoids of Stink Bugs

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Tachinid parasitoids in the subfamily Phasiinae are important natural enemies of heteropteran bugs. Host location by these flies occurs via antennal reception to the pheromones of their hosts, however little is known regarding the mechanisms which underlie host selection. Halyomorpha halys, the invasive brown marmorated stink bug, represents a potential novel host species in North America. This study was conducted to determine the suitability of H. halys as a host for phasiine species, as well as assessing cues used in host selection by the genera Gymnoclytia and Gymnosoma. Field attraction to pentatomid pheromones by both phasiines and pentatomids in Southwest Ohio were investigated and preliminary laboratory host-selection experiments were conducted. In 2015, from June 23 to September 16 pyramid-type traps were baited with three pentatomid-pheromone lures and were monitored in agricultural and semi-natural locations. Trap catches included specimens from seven different phasiine species and three different pentatomid species. During preliminary oviposition trials using Gymnoclytia occidua, attacks were observed on Euschistus spp. bugs, Podisus maculiventris, and H. halys. However, no parasitoids were successfully reared from H. Halys. Field parasitism by a Gymnoclytia sp. female on H. halys was later directly observed, and both adults and nymphs of H. halys were found bearing parasitoid eggs in the field. Preliminary results suggest that H. halys may be a “sink” for native phasiine parasitoids.


Presented at the XXV International Congress of Entomology, September 25-30, 2016 in Orlando, FL.