Impact of acetamiprid, glyphosate, and sweet orange essential oil across Mediterranean bees.

Bees (Hymenoptera, Apoidea) are in decline due to different anthropogenic factors, such as the use of agrochemicals. Currently, the majority of the pesticide risk assessments on bees includes social species. However, solitary ground-nesting bees are the most common in Mediterranean areas. Here, we assessed the topical toxicity of products commonly used in agriculture on different social and solitary Mediterranean bees: Andrena impunctata, Andrena nigroolivacea, Andrena stabiana, Andrena vetula, Eucera grisea, Osmia bicornis, Bombus terrestris, and Apis mellifera. We tested the neonicotinoid acetamiprid, the herbicide glyphosate and a botanical biopesticide based on sweet orange essential oil (EO) at the field dose, with observation of mortality up to 10 days. Acetamiprid was the most toxic compound, especially for the Andrena species, where it caused 100% mortality within 24 to 48 hours, with several neurological symptoms being observed. Acetamiprid also reduced the survival of O. bicornis, but to a more limited extent than in Andrena species. The second most toxic product was the sweet orange EO, which in particular caused 100% mortality after 48 hours to Andrena nigroolivacea, and was the only product that reduced the survival of Eucera grisea and Apis mellifera. None of these products reduced the survival of Bombus terrestris. Glyphosate reduced the survival of the bee species to a lesser extent. These results show how sensitivity to pesticides varies in different bee species, highlighting the need for additional model species in current bee risk assessments.