Difference in the impacts of the neonicotinoid dinotefuran administered through sugar syrup from that through pollen paste on a honeybee colony in the long-term field experiment

Abstract

Summary We have previously examined the impact of neonicotinoid pesticides, dinotefuran and clothianidin, on honeybee Apis mellifera colonies in long-term field experiments when they were simultaneously administered through both vehicles of sugar syrup and pollen paste (Yamada et al., 2012). The independent effect of a pesticide through two vehicles has not been studied in our previous work. In this paper, we investigated the independent impact of dinotefuran through each of the two vehicles. We confirmed that dinotefuran intake per bee until colony extinction due to administration through pollen paste (DF-TIPP) was roughly one-fifth as much as that through sugar syrup (DF-TISS). The intake was largely independent of dinotefuran concentration. We considered the possibility of DF-TIPP per bee as an indicator to assess the impact of persistent pesticide on a honeybee colony in a practical apiary. This work has replicated the finding that a honeybee colony has dwindled away to nothing after assuming an aspect of a colony collapse disorder (CCD) by administration of the neonicotinoids dinotefuran and clothianidin in our previous work, regardless of the vehicles. In addition, a failure in wintering was observed in case of administration of dinotefuran with the lowest concentration in this work even if the colony appeared vigorous before winter. We can infer that a CCD and a failure in wintering may have the same roots of chronic toxicity of neonicotinoids under conditions of low concentrations due to the persistency and high toxicity which are characteristic of them.

Long-term field experiment on the impacts of the neonicotinoid dinotefuran and the organophosphate fenitrothion on a honeybee colony

“…According to our previous works (Yamada et al , 2012; Yamada et al , under submission), we have confirmed that high concentrations in sugar syrup (dinotefuran of 10 ppm; clothianidin of 4 ppm), which is used also to make pollen paste after mixing it with pollen, collapsed the honeybee colonies due to acute toxicity, low pesticide concentrations in sugar syrup (dinotefuran of 1 ppm; clothianidin of 0.4 ppm) collapsed the colonies due to chronic toxicity after having assumed the appearance of a colony collapse disorder (CCD) or an failure in wintering, and middle concentrations in sugar syrup (dinotefuran of 2 ppm; clothianidin of 0.8 ppm) damaged the colonies due to acute toxicity at the start of administration and due to chronic toxicity at the later period after having assumed the appearance of CCD and finally collapsed them.…”