A recent study has found neonicotinoids, the world’s most commonly used insecticide, when fed to queen bees, caused them to lay two-thirds fewer eggs when compared to queen bees in unexposed colonies. Because the queen bee is the only individual in the colony that can reproduce, a reduction in its fertility can be detrimental to the whole colony. Moreover, the study found that exposed colonies were less productive (i.e. collected and stored less pollen; removed less infested or diseased pupae).
Scientists at the University of Nebraska-Lincoln and the University of Minnesota, had their study recently published in the journal Scientific Reports.
"One queen can lay up to 1,000 eggs a day. If her ability to lay eggs is reduced, that is a subtle effect that isn't (immediately) noticeable but translates to really dramatic consequences for the colony." - Judy Wu-Smart, lead study author
The scientists also found colonies exposed to imidacloprid, a type of neonicotinoids, collected and stored less pollen than insecticide-free colonies, and removed just 74 percent of mite-infested or diseased pupae that can infect the entire hive, compared to 95 percent removal by unexposed bees.
The results from this study indicate that risk-mitigation efforts should focus on reducing neonicotinoid exposure during the early spring when colonies are smallest in size and queens are most vulnerable to exposure.
Given the value of honey bee populations to the US economy is estimated to be $29 Billion dollars annually , the bigger question remains as to how industrial agriculture will continue utilizing honey bee pollination to achieve desired results while managing their competing need to apply these common insecticides.
 - http://www.nature.com/articles/srep32108
 - https://www.news.cornell.edu/stories/2012/05/insect-pollinators-contribute-29b-us-farm-income
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