Impacts of a fungicide and an insecticide on pollinator visitation and wildflower fitness

Pesticide use has become widespread around the globe, and mounting evidence has demonstrated health impacts on non-target insects such as bees. However, less is known about whether the presence of these chemicals in plant tissue can alter interactions between plants, pollinators, and floral microbes. Here we asked if the presence of an insecticide and fungicide alters pollinator visitation, the abundance of floral fungi, and seed set.We treated the wildflower <i>Penstemon strictus</i> (<i>N</i> = 126) with commercially available products containing the insecticide imidacloprid, the fungicide tebuconazole, the combination of both products, or a water control.We found the best predictor of pollinator visitation was flower number, not treatment; although flower number indirectly enhanced visitation to plants treated with the fungicide and plants treated with the combination of both chemicals, fewer flowers reduced visitation to insecticide treated plants. No clear patterns emerged in the abundance of floral fungi, which was not strongly affected by either visitation rates or chemical treatments. Finally, seed number and mass were positively related to visitation. However, although plants treated with the fungicide alone or in combination received the most visits, seed number and mass were lower than expected in these treatments, and we found evidence for direct negative effects of all chemical treatments on seed metrics (although these effects were variable).This study shows that plants containing harmful chemicals can be visited just as frequently, if not more, as those without. The inadvertent contamination of wildflowers with multiple agricultural chemicals is increasingly common and risks forming an ecological trap for pollinators that are not deterred by plants that pose a health risk. Finally, the impact of pesticides on wild plants is rarely considered, and we urge future studies to further examine downstream consequences of this exposure to wild plant fitness.