No impact of neonicotinoids on male solitary bees <scp> <i>Osmia cornuta</i> </scp> under semi?field conditions

The ubiquitous use of agrochemicals is one driver for the ongoing loss insect biomass and diversity. Data show that field-realistic concentrations neonicotinoid insecticides can negatively affect both population density fitness solitary bees. However, underlying mechanisms these effects remain poorly understood. Here, using an established semi-field experimental set-up Osmia cornuta as a bee model, we examined common insecticide (clothianidin) on male larvae adults. Besides measuring lethal (i.e., overwintering success adult survival) sub-lethal endpoints emergence mass duration), examined, first time, potential reproductive physiology sperm quantity viability). data revealed no significant any measured response variables. This may be due to low degree clothianidin exposure (0.56 ng g?1) and/or apparent susceptibility neonicotinoids. Furthermore, it conceivable ideal foraging conditions, combined with optimal weather lack other environmental stressors, have improved ability bees cope insecticide. To reliably assess understand hazards agrochemicals, holistic approach, including laboratory, field required. Knowledge will help mitigate current global declines populations.