Acute Oral and Contact Toxicity of Three PlantProtection Products to Adult SolitaryBees <i>Osmia bicornis</i>

Abstract

Bee pollinators decline worldwide over the last decades mainly due to the widespread use of pesticides. However, the data on wild bee sensitivity to pesticides are scarce. As it may not be possible to stop using pesticides at the moment due to a growing food demand, we need to make every effort to ensure that they are used in a way that do not jeopardize pollinator populations. We tested the toxicity of three agrochemicals, namely Dursban 480 EC with chlorpyrifos as active ingredient (a.i.), Sherpa 100 EC (a.i. cypermethrin), and Mospilan 20 SP (a.i. acetamiprid), to female Osmia bicornis through oral and contact exposures. The estimated LC 50 s at infinite-time were lower than concentrations recommended for field application for Dursban in both exposure routes, whereas in case of Sherpa and Mospilan the values were lower for oral exposure only. Regardless of the exposure route, high mortality in less than 24 hours was observed in Dursban-treated bees at a fraction of concentration actually used by farmers in the field, indicating high toxicity of this product to O. bicornis. Therefore, some commonly used insecticides may cause unacceptable effects to pollinators even when applied in the field according to recommendations, indicating the urgent need for revising current pesticide usage regulations.