Abstract:
Cognitive functions, such as learning, are mediated by nicotinic acetylcholine receptors (nAchRs) in insects. Dinotefuran is a neonicotinoid insecticide developed to target these receptors. In this study, two groups of third instar larvae of Aedes (Stegomyia) aegypti mosquitoes were exposed to two treatments—one group was subjected to 0.01 mg/L dinotefuran, the other with water, serving as the untreated group. After emergence to adulthood, the mosquitoes were subjected to a modified bi-directional conditioning and short-term memory assay by using two contrasting visual cues as neutral stimuli and meal palatability as reinforcing stimuli. Results show that untreated group exhibited a change in feeding preference from the palatable 10% sugar solution to aversive 40% saline solution. It is proposed that this change of preference is a manifestation of a noveltyseeking behaviour which might be due habituation to sucrose solution and being able to associate the visual cue with the meal palatability. Dinotefuran-treated mosquitoes, however, exhibited no switching of preference but a reduced preference for the sucrose solution. This might be due to their reduced susceptibility to habituation that led to nonexpression of the novelty-seeking behaviour. The results emphasize the role of learning in mosquito feeding behaviour and how it is affected by insecticides with potential implications for vector control.
