Indirect effects of agricultural pesticide use on parasite prevalence in wild pollinators

• Published in: Agriculture, ecosystems & environment Vol. 258; pp. 40 - 48
• Main Authors: Evans, Alexander N., Llanos, Joseph E.M., Kunin, William E., Evison, Sophie E.F.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 15.04.2018; Elsevier BV
• Subjects: Abundance; Agricultural land; Agricultural management; Agriculture; Agrochemicals; Ascosphaera; Bees; Community structure; Disease control; disease prevalence; Disease transmission; Epidemiology; honey bees; Megachile; Microsporidia; Neonicotinoid; Nesting; Offspring; Organic chemistry; Osmia rufa; Parasite; Parasites; Pesticides; Plant reproduction; pollinating insects; Pollination; Pollinator decline; Pollinators; progeny; rearing; solitary bees; surveys; Syrphidae; wasps; Parasite; Neonicotinoid; Pollinator decline; Agriculture; Pollination
• ISSN: 0167-8809; 1873-2305
• DOI: 10.1016/j.agee.2018.02.002

•Mitigating pollinator decline requires recognizing how multiple stressors interact.•We assessed how pesticide use affected multiple measures of pollinator success.•High pesticide use areas had lower pollinator abundance, richness and diversity.•Common bee parasites were generally more prevalent in low pesticide use areas.•Pesticide use may affect pollinators indirectly by altering disease vectoring opportunities. Insect pollinators appear to be experiencing worldwide declines, a phenomenon that has been correlated both with exposure to chemical pesticides and disease prevalence. These factors have been found to have strong and often interacting negative effects on multiple pollinator species in laboratory based studies, however their interactions in the field are less clear. To try and understand the link between pesticide use on pollinator communities, and how this might impact on disease transmission, we took two complementary approaches. First, we undertook a series of pollinator surveys to assess the abundance and diversity of pollinator groups across British agricultural field sites subject to varying levels of pesticide use. We then screened the offspring of two taxa of tube nesting solitary bees (Osmia bicornis and Megachile spp.) for three parasite groups commonly associated with pollinators. We found lower pollinator abundance, group richness and diversity across agricultural sites associated with higher pesticide use. Specifically, there were fewer honey bees, hoverflies, solitary bees and wasps. Surprisingly, we found a lower prevalence of all three parasite groups in O. bicornis offspring reared in sites associated with higher pesticide use compared to lower pesticide use. We also found a lower prevalence of Ascosphaera but a higher prevalence of Microsporidia in Megachile offspring reared in sites associated with higher pesticide use compared to lower pesticide use. Together, our results suggest that agricultural sites associated with higher pesticide use may be affecting pollinators indirectly by disrupting community structure and influencing disease epidemiology and vectoring opportunities. This highlights the importance of understanding the interactions between pesticide use and disease in both managed and wild bee populations for the future mitigation of pollinator declines.