Roadside pollinator populations and the negative impact of intensive roadside vegetation maintenance

Insect population declines are increasingly well documented, and pollinators are among these threatened taxa. However, modified roadside habitats may be suitable for supporting pollinator populations.

This study used a landscape‐scale natural experiment to test how different roadside maintenance practices affect bees (Hymenoptera: Anthophila) and flower flies (Diptera: Syrphidae). Treatments studied were Low Intensity (≤2 mowing events per year and spot‐spraying/hand‐pulling of invasive plants) and Business As Usual (several mowing events per year and heavy use of herbicide). Pollinators were collected at 31 sites, 24 times each, over 2 years (372 site‐visits/year).

We found that Business As Usual practices significantly reduced abundance and species richness of pollinators. However, community composition was similar across both treatments, indicating that roadsides support a fairly homogeneous pollinator community, regardless of management.

To increase pollinator abundance in roadsides, we recommend that managers adopt practices similar to the Low Intensity management of our study.