Synergistic strategies: Fungicides and entomopathogenic nematodes in turfgrass pest control

Fungicides are routinely used to protect turfgrass from fungal pathogens and control turfgrass diseases. In addition to killing fungal pathogens, fungicides can kill insect pests and negatively impact the insect immune system. Because some fungicides interfere with the insect immune responses, these fungicides may, in turn, enhance insect susceptibility to their natural enemies and thus improve the biological control of insect pests. Entomopathogenic nematodes (EPNs) are natural enemies that can be used to control turfgrass pests. If fungicides enhance pest susceptibility to EPNs, EPNs can be applied simultaneously with fungicides already being used for disease management to optimize the biological control of turfgrass pests. In this research project, we evaluated fungicides for synergistic interactions with EPNs to control the annual bluegrass weevil, Listronotus maculicollis, a major pest of short-mown turfgrasses, including annual bluegrass and creeping bentgrass. Annual bluegrass weevil densities were estimated in response to fungicide treatments (untreated control, propiconazole, and pyraclostrobin) and EPNs (untreated control and Steinernema carpocapsae) in a factorial design. The information gained from this project can optimize the biological control of turfgrass insects using EPNs by leveraging potential synergism with agrochemicals already being used on golf courses.