Tachinid Parasitoids of the Adult Stage of Phytophagous Stink Bugs: A Vacant Niche in Piezodorus guildinii (Hemiptera: Pentatomidae)

ABSTRACT Piezodorus guildinii and Nezara viridula (Hemiptera: Pentatomidae) are harmful stink bug pest species. Among their natural enemies, parasitoids of two guilds attack them: oophagous and those that parasitise the adult stage. The combined impact of parasitoids of both guilds partly explains the decline in the abundance of several pentatomid species. However, adults of P. guildinii are not commonly parasitised, unlike N. viridula , which is frequently attacked by Trichopoda pictipennis (Diptera: Tachinidae). This suggests a potential vacant niche for this species. Under particular circumstances, a parasitoid may include a non‐preferred species among its potential hosts; selectivity decreases as the life expectancy of a parasitoid decreases, lowering the quality threshold below which hosts are rejected. We evaluated the potential of P. guildinii as a host for T. pictipennis females of different ages. The performance of young parasitoid females (around 2 days old) and old parasitoid females (around 6 days old) using P. guildinii or N. viridula was assessed. A total of 42 P. guildinii adults were parasitised, yielding 25 pupae and 13 adult flies (F1 generation). Parasitism by T. pictipennis was higher on N. viridula than on P. guildinii , particularly for young females, showing significantly greater parasitism and egg deposition on their preferred host. Female age had no consistent effect on parasitism rates within host species, although old females were more likely to parasitise P. guildinii than young females. Overall, T. pictipennis was able to develop on P. guildinii , but performance and offspring size were reduced when compared to the development on N. viridula . These data indicate that T. pictipennis can potentially parasitise P. guildinii and is able to develop on this host, making it of interest for the design of integrated pest management strategies against this pest.