Evaluating the potential utility of an electrostatic sprayer and a tractor-mounted vacuum machine for Lygus hesperus (Hemiptera: Miridae) management in California's coastal strawberry

Abstract

Lygus hesperus Knight (Hemiptera: Miridae) is an important pest of strawberry in the central coast of California. Both adults and nymphs of L. hesperus feed on developing strawberry fruits causing cat-faced fruits (unmarketable). Although multiple tactics, such as vacuuming with tractor-mounted vacuum machine or the application of an insecticide, are used to manage L. hesperus, the combined effects of these tactics have not been thoroughly examined. Furthermore, the use of an electrostatic sprayer for L. hesperus management has not been tested. The objectives of the present study were to determine 1) the individual and combined effects of sulfoxaflor insecticide and vacuuming on L. hesperus and their feeding damage, and 2) the efficacy of sulfoxaflor when sprayed using an electrostatic sprayer at various rates of water volume against L. hesperus. The results showed that the vacuum alone did not reduce L. hesperus populations to untreated control (UTC). The treatments that involved sulfoxaflor, both individually and when combined with the vacuum reduced the number of L. hesperus and percentage cat-faced fruits compared to UTC. Neither the “bug vac” nor the sulfoxaflor had any impact on the capture of predaceous heteropterans and spiders compared to UTC. In various water volume treatments applied using electrostatic sprayer, the number of L. hesperus nymphs and percentage of cat-face fruits was significantly lower than in UTC treatment and was comparable to conventional sprayer. The numbers of predaceous heteropteran and spider captures were not significantly different between the treatments applied using electrostatic versus conventional sprayers. These results implies that effective insecticide will continue to the best tactic to reduce L. hesperus and damage. Use of electrostatic sprayer has a potential whereas, vacuum method will need further refinement for L. hesperus control.