Pesticides impairs olfaction

Neonicotinoid pesticides have been suggested as a major cause for honey bee colony collapse disorder, and a new study by Ken Tan from Xishuangbanna Tropical Botanical Garden in China lends support to this theory. They observed that sub-lethal doses of neonicotinoids can impair the ability of Asian honey bees (Apis cerana) to associate floral odours with nectar rewards, thereby facilitating foraging and pollination. The scientists captured wild foragers and fed them sucrose with the neonicotinoid imidacloprid , which is widely used in China. Exposed and un-exposed bees were then subjected to an olfactory conditioning protocol, testing for both short term (10 minutes) and long term (11 hours) learning. The negative effect on olfactory learning was evident for both adults and larvae but manifested in different ways. Adult bees displayed 1.6-fold reduced long term learning acquisition, whereas larvae exhibited almost 5-fold poorer short term learning acquisition when they subsequently grew up to become adult bees. In the latter case, however, long term learning was not affected. The authors have no explanation as to why larval-treated bees recovered their longer-term memories, while this was not the case for bees treated as adults.

Source: Tan et al (18 June 2015) Scientific Reports doi:10.1038/srep10989