Effect of imidacloprid on associative learning during the early adulthood of honeybees (Apis Mellifera)

MENGONI CAROLINA; FARINA WALTER M.

Huerta Grande

Congreso; II Congreso Latinoamericano de Ecología Química; 2012

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Imidacloprid (IMI) is a neonicotinoid used for its high selective toxicity in insects. However, its effect on non-target and beneficial insects, such as the honeybee Apis mellifera, is still controversial. IMI acts as a nicotinic agonist. Moreover, these cholinergic pathways take part in the acquisition and retention stages of associative learning. Therefore, we used IMI to assess this system?s role and the changes it suffers during the first days of the honeybee?s adult life. Harnessed bees 2-10 days old were exposed to sub-lethal doses of IMI (0, 0.25 or 0.50ng per bee) administered topically on their thoraxes 15 minutes prior to an olfactory conditioning procedure based on the proboscis extension response (PER). Conditioning consisted of 5 consecutive presentations of a pure odour paired with sucrose solution as a reward. Retention tests were performed immediately after conditioning or 24 hours later. Acquisition and retention were impaired as a result of acute exposition to both treatment doses of IMI. These outcomes differed amongst age groups. We propose that IMI interferes with learning and memory processes in recently emerged bees and that the nicotinic cholinergic pathways seem to suffer modifications during the first days of adulthood, along with other changes in the nervous system.