Floral abundance and richness drive beneficial arthropod conservation and biological control on golf courses

Golf courses are among the largest, most ubiquitous highly maintained urban green spaces in the U.S. Although their primary function is recreation, a large portion of golf course land is not actively in use, which presents opportunities to create more ecologically functional areas. Golf courses around the world are converting these out-of-play areas to alternative habitats, but few do so using evidence that maximizes their benefit. Previous studies have investigated effects of conservation plantings on golf courses, but none have isolated the biological control services of flying natural enemies and few investigated effects on native bees. In this study, we ask if converting out-of-play maintained turfgrass areas into wildflower habitats increases bee and insect natural enemy abundance and diversity and their associated ecosystem services. We created wildflower habitats at two levels of species richness and compared their effects on insects within and around them to turfgrass plots. To quantify effects on biological control, we deployed sentinel prey Spodoptera frugiperda larvae, excluding ground-dwelling predators. As predicted, we found that converting turfgrasses to flowering habitats increased bees and natural enemies on golf courses. However, high wildflower species richness was an important factor in promoting native bees and natural enemies. We found that wildflower habitats, particularly those with highest floral richness, increased biological control rates in adjacent turfgrass areas by up to 50% compared to turfgrass controls. Our results indicate that purposefully designed conservation plantings on golf courses can help support insect pollinators while also augmenting biological control of turfgrass pests.