Testing the potential of entomopathogenic nematodes in attract-and-kill and autodissemination approaches in the control of Queensland fruit fly, Bactrocera tryoni

BACKGROUND: Many studies have demonstrated that tephritid fruit fly larvae are highly susceptible to entomopathogenic nematodes (EPNs) and may become infected as they enter the soil to pupate. However, the susceptibility of adult tephritids and their suitability as EPN targets have been less studied. We performed laboratory assays with 12 Australian EPN strains of Heterorhabditis bacteriophora, Heterorhabditis indica and Heterorhabditis zealandica in adults of the Queensland fruit fly, Bactrocera tryoni. Infective juveniles were delivered in a yeast hydrolysate solution that is attractive to flies. We also measured the flight ability of adults up to 3 days after treatment. RESULT: Flies that consumed the EPN-yeast preparation experienced 72.8-84% mortality. Between 33.5% and 46.2% of EPN-treated adults were still able to fly before death following treatment, mostly within the first day, thereby contributing to EPN dispersal. Another 31.9-39.9% of EPN-treated flies that were unable to fly died as a result of EPN treatment. Overall, >65% of flies that died following EPN treatment had visible signs of infection and EPN reproduction. CONCLUSION: Our study is foundational to the development of attract-and-kill and autodissemination approaches involving EPNs in fruit fly control. Furthermore, H. indica and H. zealandica strains showed the highest potential as biocontrol agents against adult flies.