Laboratory assessment of the speed of action on honey bees of orally dosed insecticides

Abstract

Abstract A laboratory test to determine the times taken by orally dosed pesticides to affect and paralyse honey bees is described. Ten insecticides were tested at levels 1.5, 2, and 4 times that of their LDs 90. Results rre expressed as the times taken after consumption of the test doses for 50% and 90% of the bees to become affected and later paralysed. At the lowest dose methomyl, the fastest-acting insecticide, affected bees approximately 16 times faster than the slowest, monocrotophos. Possible difficulties in interpreting the results of field trials with fast-acting compounds are discussed.