Susceptibility of the house fly pupal parasitoid Muscidifurax raptor (Hymenoptera: Pteromalidae) to the entomopathogenic bacteria Bacillus thuringiensis and Brevibacillus laterosporus

Muscidifurax raptor, an ectophagous pteromalid parasitoid of various muscid flies such as Musca domestica, can be mass-reared and released in poultry and livestock farms for house fly control. Entomopathogenic bacteria, such as Bacillus thuringiensis, are commercialized for the biological control of different insect pests, but they may have side-effects on other natural enemies. In this study, the susceptibility of M. raptor to three strains of entomopathogenic bacteria (B. thuringiensis subsp. kurstaki (Btk) strain HD1, B. thuringiensis subsp. israelensis (Bti) strain ONR60A, and a new and promising strain of Brevibacillus laterosporus toxic to the house fly) was evaluated. Adult wasps were fed a diet treated with high bacterial concentration (>109 spores/g of diet) of Btk, Bti or B. laterosporus. Btk had no detectable effect on M. raptor, B. laterosporus caused only a slight effect on M. raptor adults, and Bti caused a significant mortality and reduction in the reproductive potential of the wasp. In another test in which parasitoids developed on house fly pupae from pre-treated larvae, Bti caused significant reductions in the development time (6.1%) and in adult emergence rate (up to 59.2%) of M. raptor compared to the control. By contrast, tritrophic interaction (house fly-bacteria-parasitoid) did not occur with B. laterosporus. The compatibility of the B. laterosporus strain in house fly integrated management strategies with parasitoids is promising.