Impact of alpha-cypermethrin on honey bees foraging on spring oilseed rape(Brassica napus)flowers in field conditions

摘要

BACKGROUND:Cruciferous oil-bearing crops have gained in importance worldwide.The expansion of the growing area of these crops has caused a proliferation of pests.Exposure to organophosphate,carbamate and pyrethroid insecticides has been associated with bee poisoning in food crops.This study examines the repellent effect of alpha-cypermethrin on the number of foraging honey bees,Apis mellifera L.,on fields of spring oilseed rape,Brassica napus L.var.oleifera.RESULTS:The first experiment was conducted on differently sprayed 10 m2 experimental plots where alpha-cypermethrin was applied at different times.Another experiment was conducted on a 4ha seed production field divided into two parts:one part was treated with alpha-cypermethrin and the other was not treated with this insecticide.The results show that there was no difference in the number of honey bees between alpha-cypermethrin-treated and untreated patches.The result persisted through three observation years,regardless of varying flower and honey bee densities.CONCLUSION:No repellent effect of the insecticide on honey bees was found even 24h after spraying.The density of oilseed rape flowers most likely played a major role in choosing the foraging area.