Increased Acetylcholinesterase Expression in Bumble Bees During Neonicotinoid-Coated Corn Sowing

Abstract

While honey bee exposure to systemic insecticides has received much attention, impacts on wild pollinators have not been as widely studied. Neonicotinoids have been shown to increase acetylcholinesterase (AChE) activity in honey bees at sublethal doses. High AChE levels may therefore act as a biomarker of exposure to neonicotinoids. This two-year study focused on establishing whether bumble bees living and foraging in agricultural areas using neonicotinoid crop protection show early biochemical signs of intoxication. Bumble bee colonies (Bombus impatiens) were placed in two different agricultural cropping areas: 1) control (≥3 km from fields planted with neonicotinoid-treated seeds) or 2) exposed (within 500 m of fields planted with neonicotinoid-treated seeds), and maintained for the duration of corn sowing. As determined by Real Time qPCR, AChE mRNA expression was initially significantly higher in bumble bees from exposed sites, then decreased throughout the planting season to reach a similar endpoint to that of bumble bees from control sites. These findings suggest that exposure to neonicotinoid seed coating particles during the planting season can alter bumble bee neuronal activity. To our knowledge, this is the first study to report in situ that bumble bees living in agricultural areas exhibit signs of neonicotinoid intoxication.

Comparative Modelling, Toxicological and Biochemical Studies of Imidacloprid and Thiamethoxam Insecticides on the House Fly, Musca domestica L. (Diptera: Muscidae)

“…The treatment of adult house flies with IMI and THIA enhanced AChE activity but with different levels. THIA treatment exhibited significantly higher AChE activity compared to the IMI treatment these findings agree with Samson-Robert et al (2015) who approved that the neonicotinoids are the only insecticide that cause an increase in AChE activity. In addition, increased AChE activity has also been reported in response to exposure to neonicotinoids, in both honey bees Boily et al (2013).…”

Impacts of neonicotinoid seed treatments on soil-dwelling pest populations and agronomic parameters in corn and soybean in Quebec (Canada)

“…A vast body of scientific literature has demonstrated that the scale of use of those insecticides has resulted in widespread contamination of agricultural soils, freshwater resources, wetlands, and non-target vegetation, along with repeated and chronic exposure of the organisms inhabiting these habitats to potentially harmful concentrations of these pesticides [2,5,6,7,8,9,10,11,12,13]. In Canada, widespread contamination of water [14,15,16,17,18,19,20,21] and impacts on non-target organisms, such as pollinators [22,23,24,25], have already been demonstrated.…”

Interaction of field realistic doses of clothianidin and Varroa destructor parasitism on adult honey bee (Apis mellifera L.) health and neural gene expression, and antagonistic effects on differentially expressed genes

“…Also, sublethal neonicotinoid exposure can be detrimental to hygienic and grooming behaviours [14,29,32], longevity [32], humoral immunity [33] cellular immunity [34], hypopharyngeal gland development [35] and Malpighian tubule system function [36]. Sublethal doses of neonicotinoids can affect gene transcription, such as the down-regulation of differentially expressed genes (DEGs) for biosynthetic processes detected by RNAseq [37] and up-regulation of acetylcholinesterase (AChE) detected by qRT-PCR [38,39]. Acetylcholine has been associated with learning in honey bees [40], and thus the effect of agonist of nAChR, such as clothianidin, with its subsequent effect on the enzyme acetylcholinesterase could have detrimental effects on bee behaviour.…”