Evaluation of acute toxicity of thiamethoxam in alg erian honeybee apis mellifera intermissa and apis mellifera sahariensis

Thiamethoxam [3-(2-chlorine-1, 3-thiazole-5-ylmethy l)-5-methyl-1,3,5-oxadiazinan-4-ylidene(nitro) amin e], a systemic insecticide of the group of neonicotinoids with a large spectrum of action at low concentrati ons. It is used in the control of sucking insects and some chewing species , b cause of its excellent absorption and transloca tion in plants. The acute toxicity of contact and oral applications two Apis mellifera subspecies, Apis mellifera intermissa nd Apis mellifera sahariensis was investigated. In all toxicological studies, eac h dose included three cages of 20 individuals and each study was replicated three times. The dose–mor tality relation revealed directly proportional rela tionship between the administered dose of thiamethoxam and mortality obs erved. The mortality is reached maximum at 24 hours after treatment with doses above 50 ng / bee after oral application . Response kinetics showed classic kinetics. The hi gher the dose of thiamethoxam and faster is high mortality appears. After oral intoxication, the LD50 values of thiamet hoxam at 24h were about 12,3 ng/bee for A. m. intermissa and 13.3 ng/bee for A. m. sahariensis. After contact application, the LD50 values at 24 h were approximately 26 ng/bee for A. m. intermissa and 43.3 ng/bee for A. m. sahariensis.