Incidence of Tachinid Parasitism of Several Stink Bug (Heteroptera: Pentatomidae) Species Associated with Soybean1

Abstract

Parasitism by tachinids of 13 species of pentatomids collected primarily in soybean fields from four locations in Louisiana was evaluated during a 3-year study. Parasitism was determined by examining the hosts externally for the presence of parasite eggs plus holding them in the laboratory and observing for parasite emergence. Parasite species composition was determined for each pentatomid. Seasonal rates of parasitism were evaluated for the pest species, Nezara viridula (L.), Acroslernum hilare (Say), and Euschistus spp. Seven tachinid species were recovered. Only Trichopoda pennipes (F.) was observed developing on N. viridula . Supernumerary oviposition, with up to 19 and 25 eggs observed on single N. viridula and A. hilare males, was common by this parasite. N. viridula were dissected in the laboratory to determine the incidence of parasite larvae, the gonadal developmental stages of males and females most commonly parasitized, and the effects of parasitism on the fecundity of parasitized female hosts. Although significantly more parasite eggs were deposited on males than on females, the percent with parasite larvae and number of larvae per host were not statistically different between sexes. Significantly more of the N. viridula bearing larvae were in the later compared with the earlier gonadal developmental categories. The mean number of eggs per reproductively active female was significantly reduced in parasitized N. viridula . Parasitism of N. viridula was higher in collections made from cowpea than from soybean.