Methyl parathion modifies foraging behaviour in honeybees (Apis mellifera).

We examined the effects of sublethal doses of an organophosphorus insecticide, Methyl Parathion (MeP), on the foraging behaviour of honeybees (Apis mellifera ligustica) in a flight cage. The results revealed that MeP modified the frequency of visits to a feeding station to which the bees had previously been trained. A dose of 50 ng per animal elicited an increase in the frequency of visits to the feeder, compared to control animals. A dose of 10 ng, on the other hand, led initially to a decrease in the visit frequency, followed by an increase to a level above that of the controls. A hypothesis is presented to account for the way in which MeP affects foraging behaviour. We propose that the behavioural assay presented here could be useful as a preliminary screening test to study sublethal effects of pesticides on foraging performance in honeybees.