Abstract
Insect species richness and abundance has declined rapidly over the last few decades. Various stressors, such as the conversion of natural habitats, climate change, land-use intensification, agrochemicals and pathogens, are thought to be major factors in this decline. We treated female bees of two common pollinator species in Europe, Osmia bicornis and Bombus terrestris, with a field-realistic dose of the neonicotinoid clothianidin. We tested its effects on the foraging behavior of O. bicornis under semi-natural conditions and on the antennal sensitivity of both bee species to common floral volatiles by using electroantennography. Clothianidin negatively affected the foraging behavior in O. bicornis by decreasing the number of flowers visited per foraging flight and by increasing the time per flower visit and the searching time between two flowers. It also decreased the antennal sensitivity to 2-phenylethanol in the two bee species. Thus, clothianidin is clearly a threat for bees via its effects on their foraging behavior and antennal sensitivity and is hence probably detrimental for pollination and the reproductive success of bees.
Highlights
Biodiversity, especially species richness, abundance and the distribution of pollinators is globally declining (Potts et al, 2010; van der Sluijs et al, 2013; Godfray et al, 2014; Goulson et al, 2015; Hallmann et al, 2017)
In order to increase our knowledge concerning the effects of neonicotinoids on wild bees, we have studied the effects of clothianidin on the foraging behavior and antennal sensitivity in the red mason bee Osmia bicornis and the buff-tailed bumblebee B. terrestris
Bees treated with clothianidin exhibited a significantly longer flower visiting time for Ranunculus spp. (Figure 1C, Mann–Whitney U test: W1,16 = 7, p = 0.006) as compared with C. biennis
Summary
Biodiversity, especially species richness, abundance and the distribution of pollinators is globally declining (Potts et al, 2010; van der Sluijs et al, 2013; Godfray et al, 2014; Goulson et al, 2015; Hallmann et al, 2017). Imidacloprid, thiamethoxam, and clothianidin (a breakdown product of thiamethoxam) are the most toxic (Scott-Dupree et al, 2009; Stokstad, 2013; Botías et al, 2015) They have been used as a seed coating or have been applied via foliar or soil treatment until their ban in Germany by the end of 2020 (Elbert et al, 2008; Fent, 2013)
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