Alfalfa trap cropping to manage Lygus lineolaris in North Central strawberry production

Lygus lineolaris, the tarnished plant bug, is a major pest of strawberries in the Eastern United States and the primary insect concern of strawberry growers in Wisconsin. However, few effective, non-chemical Lygus management strategies are currently available to growers. We sought to address the need for sustainable Lygus management strategies by examining the potential of alfalfa as a trap crop in this system, as similar strategies have shown efficacy against other Lygus species. Perimeter strips of alfalfa were established alongside quarter-acre strawberry plots at three farms in Southern Wisconsin. Each treatment plot (with alfalfa) was paired with an unmodified control plot. Insects were collected from the edge and center of each plot and L. lineolaris abundance was compared between treatment and control plots using generalized linear mixed models. Trap cropping was associated with significant reductions in the Lygus population in both years of this study, as trap cropped strawberry plots yielded 60% and 42% fewer Lygus bugs than control plots in 2020 and 2021, respectively. These data suggest that alfalfa perimeter plantings can be an effective tool for reducing Lygus populations in North Central strawberry production and by incorporating an alfalfa trap crop into their production system, growers may be able to reduce pesticide inputs.