Effects of sublethal doses. Impairment of olfactory learning performances in the honey bee after long term ingestion of imidacloprid

• Published in: Hazards of Pesticides to Bees no. 98; pp. 113 - 117
• Main Authors: Decourtye, A. ((Institut National de la Recherche Agronomique, Bures sur Yvette (France). Centre de Versailles Grignon, Laboratoire de Neurobiologie Comparée des Invertébrés)), Le Metayer, M, Pottiau, H, Tisseur, M, Odoux, J.F, Pham Delegue, M.H
• Format: Journal Article
• Language: English
• Published: Paris (France) INRA 2001
• Subjects: ABEILLE OUVRIERE; ABEJAS OBRERAS; ANIMAL LEARNING; APIS MELLIFERA; APPRENTISSAGE ANIMAL; APRENDIZAJE ANIMAL; BEHAVIOUR; COMPORTAMIENTO; COMPORTEMENT; FLIGHT; IMIDACLOPRID; INGESTION TOXICITY; INSECTICIDAS; INSECTICIDE; INSECTICIDES; OLFACCION; OLFACTION; TOXICIDAD POR INGESTION; TOXICITE PAR INGESTION; VOL; VUELO; WORKER BEES
• ISBN: 9782738009661; 2738009662
• ISSN: 0293-1915

Although the classical means of assessing toxicity of pesticides in honey are based on the determination of mortality in acute toxicity tests, it is also important to examine the effect of ecologically relevant sublethal exposure on various aspects of the honey bee behaviours. Methods used to study learning processes and foraging behaviour were adapted to test the sublethal effects of the insecticide molecule imidacloprid (chloronicotinyl) at both individual and colony levels under confined conditions. At the individual level, we studied the effects of long term ingestion of 4-40 ppb imidacloprid (11 days administration) on olfactory learning performances using the olfactory conditioning of proboscis extension on restrained bees. At the colony level, a sugar solution containing 50 ppb of imidacloprid was fed to a colony in a flight cage (14 days administration) to determine the effects (1) on the flight activity as measured with an activity counter set at the hive entrance and (2) on the olfactory discrimination performances on an artificial flower feeder. The olfactory conditioning showed that honey bees surviving the diet contaminated with imidacloprid had reduced olfactory learning performances. Only the concentration of 4 ppb induced a percentage of mortality not significantly different from the control diet after long term ingestion. In the flight cage, the administration of imidacloprid led to a decrease in the flight activity and the olfactory discrimination performances. Thus, the decrease in the learning performances induced by imidacloprid at the individual level was confirmed at the colony level. However, it would be necessary to conduct further work on the dose-reponse relationships, and on the sublethal effects of differents pesticides, before concluding about the hazard of imidacloprid on honey bees