Behavioral impairments in Africanized Apis mellifera exposed to lethal and sublethal doses of acetamiprid, fipronil, and thiamethoxam

Abstract

The honeybee (Apis mellifera Linnaeus (Hymenoptera: Apidae)) is a crucial contributor to the maintenance of biodiversity, ecosystem function, and food security. The widespread use of pesticides, particularly neurotoxic insecticides such as acetamiprid, fipronil, and thiamethoxam, is potentially harmful to honey bees. In this study, we aimed to determine the mean lethal dose (LD50) and time-to-effect of the lethal dose of these three insecticides to assess their acute toxicity to honey bees. Furthermore, we assessed the effects of lethal and sublethal doses on two key behavioral parameters: proboscis extension reflex (PER) and locomotor activity. Briefly, bees were exposed to lethal and different sublethal doses of insecticides and their responses were evaluated at various time intervals. Acetamiprid temporarily affected honeybee foraging capacity and mobility, with signs of recovery observed after 24 h. Fipronil exhibited delayed toxicity, whereas thiamethoxam immediately affected the PER response. Overall, our study suggested acetamiprid as the safest option among the tested insecticides, considering its acute topical toxicity. Future studies should investigate the potential long-term effects of other factors on honeybee behavior.