Effects of sublethal doses of imidacloprid on young adult honeybee behaviour

MENGONI CAROLINA; FARINA WALTER M.

PLOS ONE

PUBLIC LIBRARY SCIENCE

Lugar: San Francisco; Año: 2015 vol. 10 p. 1 - 15

1932-6203

Imidacloprid (IMI), a neonicotinoid used for its high selective toxicity to insects, is 27 one of the most commonly used pesticides. However, its effect on beneficial insects 28 such as the honeybee Apis mellifera L is still controversial. As young adult workers 29 perform in-hive duties that are crucial for colony maintenance and survival, we aimed to 30 assess the effect of sublethal IMI doses on honeybee behaviour during this period. Also, 31 because this insecticide acts as a cholinergic-nicotinic agonist and these pathways take 32 part in insect learning and memory processes; we used IMI to assess their role and the 332changes they suffer along early adulthood. We focused on appetitive behaviours based 34 on the proboscis extension response. Laboratory reared adults of 2 to 10 days of age 35 were exposed to sublethal IMI doses (0.25 or 0.50ng) administered orally or topically 36 prior to behavioural assessment. Modification of gustatory responsiveness and 37 impairment of learning and memory were found as a result of IMI exposure. These 38 outcomes differed depending on age of evaluation, type of exposure and IMI dose, 39 being the youngest bees more sensitive and the highest oral dose more toxic. Altogether, 40 these results imply that IMI administered at levels found in agroecosystems can reduce 41 sensitivity to reward and impair associative learning in young honeybees. Therefore, 42 once a nectar inflow with IMI traces is distributed within the hive, it could impair in-43 door duties with negative consequences on colony performance.