И в двете има една обща нишка, която във второто изследване се признава, но под сурдинка. Системното подлагане на семействата със сублетални дози пестициди няма видими последици през лятото и есента поради бързия метаболизъм на препаратите, но дава видимо отражение на презимуването.
Как да се отреагира на това:
In a recent study that collected pollen from bee hives in seven major crops, 35 different pesticides were detected with a total residue load ranging from 23.6 to 51,310 μg/kg from an average of 9.1 pesticides per pollen sample.
Това е от първото изследване:
why do neonicotinoid treated colonies lose their ability to renew brood rearing toward the end of winter when temperatures began to rise? Considering that neonicotinoid-treated and control colonies had identical brood rearing performance prior to the arrival of winter (figure 1), the failure of neonicotinoid-treated colonies to resume brood rearing, in particular during the transition from winter to spring might be part of the interplay between sub-lethal neonicotinoid exposure and CCD.
Това е от второто:
These results, along with dose-response patterns for several colony performance endpoints prior to overwintering, clearly indicate negative impacts on honey bee colony health due to the cumulative sublethal exposure to 20 and 100 μg/kg of imidacloprid for 12 weeks during the early summer. The delayed effect of reduced winter survival was apparently due to higher rates of queen loss and broodless periods during the late summer. Interestingly, the 2009 colonies entering the winter were seemingly stronger than the 2010 colonies, yet they experienced winter mortality that was more positively associated with the level of imidacloprid exposure. We contribute this to the queenless situation that probably resulted in a higher than normal proportion of old bees going into the winter. When this occurs, although colony size may appear adequate in the fall, the bee cluster decreases faster than brood rearing can compensate in February and March and the colony can fail.