Semi-field Risk Assessment Studies Of Imidacloprid Effects On Honeybees

As an important pollinators, honeybees have a significant economic and ecological benefits. Neonicotinoids is the fastest growing insecticides in recent years and imidacloprid is the largest insecticide products in the neonicotinoids. Both oral and contact toxicity of imidacloprid to bees are high toxic testified by laboratorial acute toxicity test, but the influence effects of its field trials has not been reported in China until now. The related researches abroad shows that neonicotinoids have a great subchronic toxicity to honeybees, and some European countries have now started to forbid the use of this kind of pesticide, but it still shows an upward trend in China about neonicotinoids using. So, the research study chose imidacloprid applied in rice field under semi-field condition, the biggest one in neonicotinoids, to assess its effects on honeybees’(Apis mellifera L.) colony strength、 development situation(including eggs、larva and pupa) and flight behavior, to research the influence of imidacloprid to bees’ conoly, and study imidacloprid and other neonicotinoids effect on honeybees in further. The research conclusions should provide theoretical basis and reference for safety use of pesticides also helpful to the model establishment of high-tier risk assessment of pesticides to honeybees’conoly. The results prove that the test item20%imidacloprid soluble concentrate applied in rice field under the dose of30.0a.i.g/ha,7days before full flowering,did not show significant affect to bees’ survival、foraging and brood development; when applied in the evening of full flowering, although without significant affect to conoly strength and brood development, it caused significant affect to bees’ foraging activity in5days after application.