Using drip irrigation to distribute entomopathogenic nematodes for the control of spotted wing drosophila

Abstract

Laboratory studies suggest that entomopathogenic nematodes (EPNs) will successfully infect Drosophila suzukii, spotted-wing drosophila (SWD), a global pest of fruits including cherries, raspberries, blueberries, blackberries, and strawberries. We conducted a series of studies to determine if the EPN, Steinernema carpocapsae, can be delivered through commercial drip irrigation systems that often contain screens, and whether these applications are effective against SWD larvae/pupae. Laboratory studies confirmed that commercially sourced S. carpocapsae can indeed infect SWD pupae and teneral adults and a sieve-shaker study determined that >50 % of EPN infective juveniles (IJs) successfully moved through mesh screen filters with 0.125–0.4 mm openings. In a lathe house semi-field study, EPNs passed through drip tubing with 1 gph button emitters and grower standard drip tape with built-in 0.125 mm mesh filters and successfully infected SWD pupae. Two on-farm field studies confirmed EPNs were able to successfully move through drip tubing and infect SWD and waxworms (positive control) held in mesh sachets under raspberry vines or blueberry bushes. In the raspberry field study, distance from the injection site had little to no effect on EPN distribution.Results indicate that while EPN efficacy is influenced somewhat by irrigation specifications, such as filter mesh size, emitter type and spacing, drip systems with 120-mesh screens or with larger can successfully deliver nematodes resulting in SWD infection in berry cropping systems.