Role of non-bee flower visitors in a fragmented prairie ecosystem

The majority of flowering plants require insect-mediated pollination for their survival, reproduction, and persistence in the environment. While a large portion of these pollination services are provided by bees, other insects also visit flowering plants and may contribute to their pollination. We sampled insects from seven sites of remnant Palouse Prairie, a fragmented bunchgrass prairie located in the Pacific Northwest that has experienced extreme habitat loss. Insects were collected directly from the inflorescences of native wildflowers for the entirety of the flowering season in 2022 and 2023 to investigate the plant-pollinator interactions present in this florally diverse ecosystem. We collected 9,576 insects, of which 3,782 (39.7%) were insects other than bees. The most common were flies (21.9%) and beetles (13.7%), with smaller numbers of wasps and moths. We found that plants varied in the composition of their insect visitors but were commonly visited by large numbers of non-bee insects. A subset of the most common non-bee species were swabbed with a glycerin-glycol fuchsin gel and pollen loads counted to evaluate whether they are capable of transporting pollen between plants. Non-bee insects varied in their pollen loads but typically carried notable amounts of accessible pollen, indicating that they may be serving as effective pollinators.