THE NEONICOTINOID IMIDACLOPRID IMPAIRS LEARNING; LOCOMOTOR ACTIVITY LEVELS AND SUCROSE SOLUTION CONSUMPTION IN BUMBLEBEES (BOMBUS TERRESTRIS).

Bumblebees carry out the complex task of foraging to provide for their colonies. They also conduct pollination, an ecosystem service of high importance to both wild plants and entomophilous crops. Insecticides can alter different aspects of bumblebee foraging behaviour, including the motivation to leave the hive, finding the right flowers, handling flowers, and the ability to return to the colony. In this study we assessed how the neonicotinoid imidacloprid affects bumblebee's foraging behaviour after exposure to four different treatment levels, including field-realistic concentrations (0 (control), 1, 10 and 100 μg/L), through sucrose solution over nine days. We observed the behaviour of several free-flying bumblebees simultaneously foraging on artificial flowers in a flight arena to register the bees' complex behaviour post exposure. To conduct a detailed assessment of how insecticides affect bumblebee locomotor behaviour, we used video cameras and analysed the recordings using computer vision. We found that imidacloprid impaired learning and locomotor activity level when the bumblebees foraged on artificial flowers. We also found that imidacloprid exposure reduced sucrose solution intake and storage. By using automated analyses of video recordings of bumblebee behaviour, we identified sub-lethal effects of imidacloprid exposure at field realistic doses. Specifically, we observed negative impacts on consumption of sucrose solution, as well as on learning and locomotor activity level. Our results highlight the need for more multi-modal approaches when assessing the sub-lethal effects of insecticides and plant protection products in general. This article is protected by copyright. All rights reserved. Environ Toxicol Chem 2023;00:0-0. © 2023 SETAC.