INCIDENTS OF POISONING OF HONEYBEES (APIS-MELLIFERA) BY AGRICULTURAL PESTICIDES IN GREAT-BRITAIN 1981-1991

Suspected cases of poisoning of honeybees by agricultural pesticides a re investigated by the Ministry of Agriculture, Fisheries and Food (in England and Wales) and the Scottish Office Agriculture and Fisheries Department (in Scotland). Studies include field visits to sites where bee mortality is recorded, examination of dead bees for disease, and a nalysis for the presence of pesticide residues. This paper reviews the results of these investigations for the period 1981-1991. Pesticide p oisoning is diagnosed from the detection of residues in dead bees, thr ough interpretation in relation to the median lethal dose (LD(50)), an d 'subsequent residue level' (SRL) determined from laboratory studies in which bees were exposed to one LD(50) dose. Overall, an annual aver age of 50 incidents were confirmed as due to pesticide poisoning, invo lving 30 pesticide active ingredients during the 1981-1991 period. In England and Wales, the principal hazards were caused by misuse of the insecticide triazophos on oilseed rape, a problem that has been reduce d to low levels during the 1980s, and by dimethoate use on a variety o f arable crops. In Scotland there were fewer incidents, most of which were associated with use of fenitrothion on raspberries, and gamma-HCH on oilseed rape. Opportunities for reducing the risks of poisoning, a nd for refining the investigation of suspected incidents, are discusse d.