Bumblebees under pollution pressure of pesticides in urban and agrarian landscapes

Pesticides are used in anthropogenically influenced bumblebee habitats, such as agricultural fields and gardens. During their foraging flights, pollinators come into direct contact with these pollutants via e.g. contaminated food sources. There is growing proof that bees are regularly exposed to mixtures of agrochemicals, but most research has been focused on honey bees ( Apis mellifera), whereas little is known about bees not belonging to the Apis genus (non-Apis). Aim of our study was to investigate the pesticide load of foraging bumblebees (Bombus terrestris) in agricultural and urban areas. We placed commercial bumblebee hives at three urban and three agrarian locations. Foragers were analysed for 24 target pesticides with focus on fungicides. In 184 out of 220 analysed field samples, residues of 15 pesticides were found. Concentrations ranged from 0.03 to 978.17 ng/g bumblebee. Most often detected pesticides were prosulfocarb (36.4% of foragers) and flutolanil (15.9%), both never documented in bumblebees before. The pesticide load was significantly different between land-uses in spring. The study highlights the importance of considering pesticide mixtures under field conditions for toxicity studies and risk assessment. The described biomonitoring approach is cheap, easy to perform and could be used to improve monitoring programs on a global scale.

Automated summary

This study investigated the pesticide load of foraging bumblebees in agricultural and urban areas. Residues of 15 pesticides were found in 184 out of 220 field samples. The study highlighted the significant differences in pesticide load between land-uses in spring.