Quantifying exposure of wild bumble bees to mixtures of agrochemicals in agricultural and urban landscapes

This study, conducted in England, attempted to expand understanding of bumble bee exposures to pesticides in both urban and agricultural settings.  During three sampling periods (in the spring, early summer and mid-summer) researchers collected and analyzed bumble bees for 19 pesticides and related agrochemicals. In total, five species of bumble bee were collected from farms and ornamental gardens. 60.7 percent of the 150 bees tested had detectable levels of at least one agrochemical compound. Of the bees with detectable pesticide levels, 71.4 percent had more than one compound detected. A bee collected in early summer from an urban site had seven pesticides detected, which was the maximum number of pesticides detected. These findings suggest that simultaneous exposure is likely in the field. The detection levels of pesticides in wild bees foraging in agricultural landscapes were generally higher than levels found in bees foraging in urban areas. Although, the highest frequency and detection levels of both neonicotinoids and the most commonly found fungicide (boscalid) were collected from bumble bees in urban gardens. Researchers also noted that the frequency and concentration of detections decreased by mid-summer in both urban and agricultural settings. In the agricultural settings that demonstrates continued, albeit reduced, exposure outside crop bloom.

By analyzing multiple species of bumble bee the researchers also attempted to determine the impact of tongue length and body mass on pesticide exposure. In general, detection frequency did not differ between the five species analyzed. That said Bombus pratorum, the species with the shortest tongue length range and lowest body mass, did have significantly lower residue levels than other species.