By Toshiro Yamada, Kazuko Yamada and Naoki Wada, Jpn. J. Clin. Ecol. （Vol.21 No.1 2012)
Abstract Recently it has become a serious problem that honeybees suddenly vanish in their colony, which is referred to as a colony collapse disorder（ CCD）. We have made it clear by the field experiments for about four months what effect neonicotinoid pesticides such as dinotefuran and clothianidin have on the occurrence of CCD. Eight colonies consisting of about ten-thousand honeybees in each colony were investigated under the practical beekeeping conditions in our apiary. In this study foods containing dinotefuran of 1 ppm to 10 ppm or clothianidin of 0.4 ppm to 4 ppm were fed into a beehive. Three levels of concentration were 10（ high-conc.）, 50（ middle-conc.） and 100 low-conc.） times lower than that in practical use. The changes of adult bees, brood and the pesticide intake in each colony were directly examined. They suggest that each colony with the pesticide administered collapses to nothing after passing through a state of CCD, the high-concentration pesticides seem to work as an acute toxicity and the low- and middle-concentration ones do as a chronic toxicity. CCD looks mysterious, but it is just one of situations where a colony dwindles to nothing. We have proposed a CCD occurrence mechanism based on our results.
The NMR spectral analyses of dinotefuran and clothianidin in aqueous solution give the speculations that both are thermally stable under the heating condition of 50 ℃ ×24 hours and dinotefuran is radiationally stable under the ultraviolet-irradiation condition of 310 nm×50 W/m2 but clothianidin is unstable.
Toshiro Yamada, Kazuko Yamada and Naoki Wada (2012) Influence of dinotefuran and clothianidin on a bee colony , Jpn. J. Clin. Ecol. Vol.21 No.1 10-23.