Interspecific Competition between the House Fly, Musca domestica L. (Diptera: Muscidae) and Black Soldier Fly, Hermetia illucens (L.) (Diptera: Stratiomyidae) When Reared on Poultry Manure

Few studies have examined the competitive interaction between the house fly (HF) and the black soldier fly (BSF). The fact that the BSF deters HF oviposition is widely cited in BSF literature, but this interaction has not been assessed in over three decades. In this study, the competitive interaction of BSF and HF larvae was observed on fresh (day 0) and aged poultry manure (manure aged for two, four, six, or eight days). Specifically, a priority effect study was conducted to determine if colonization sequence influences time to first pupariation (HF) or pre-pupation (BSF), survivorship, and weight. Results show >70% of HFs reached pupariation in all treatments except when placed on manure eight days after the initial inoculation with BSF. However, age of the resource negatively impacted time to first pupariation and puparium weight when HFs were reared alone or introduced two to eight days after BSF. No BSF pre-pupae resulted from treatments in which HFs were the pioneering species. BSFs reached the highest percent pre-pupation when reared alone on fresh manure, but BSFs may be more susceptible to the negative impacts of an aging resource, as no pre-pupae were observed when provided with six- or eight-day-old manure. Similar to HFs, age of the resource may have impacted development and survivorship; other factors such as moisture content, chemical composition, and amount of resource provided may have also impacted our results. These data may be useful in implementing BSFs as biological control agents of the HF, as well provide valuable information for facilities mass-producing HFs or BSFs for food or feed.