Systemic neonicotinoid (neonic) exposure is associated with reductions in colony size and changes in foraging behavior, according to a recent field study done by a team of scientists at Imperial College London. The senior author of the study, Richard Gill, Ph.D., stated that when neonicotinoid “exposure is relatively persistent and combined with other stressors associated with land use change, they could have detrimental effects at the colony level.” The study, Impact of controlled neonicotinoid exposure on bumblebees in a realistic field setting, assesses the effect of exposure to the neonic, clothianidin, on bumblebee foraging patterns and colony size. Clothianidin was given to 20 buff-tailed bumblebee colonies for five-weeks in a sugar solution at a concentration of 5 parts per billion, an environmentally relevant level of the pesticide. A bumblebee colony census was done before and after the field experiment, where the number of eggs, larvae, pupae, and workers bees were recorded along with the wax and pollen stores in the colony. The researchers found that the clothianidin treated colonies had fewer workers, drones and reproductive female bees compared to the colonies with no exposure. These data add to the growing body of research on sub-lethal effects, which must be considered when looking at the effects of pesticides on non-target organisms.
This study adds to the body of science that has examined the effects of neonic exposure to bee colonies under field conditions. However, neonic pesticides have long been identified as a major culprit in bee decline by independent scientists and beekeepers, yet chemical manufacturers like Bayer and Syngenta have focused on other issues such as the varroa mite. As Beyond Pesticides wrote in the 2014 issue of Pesticides and You, the issue of pollinator decline is No Longer a Big Mystery, and urgent action is needed now to protect pollinators from these toxic pesticides.
Neonics are associated with decreased learning, foraging and navigational ability, as well as increased vulnerability to pathogens and parasites as a result of suppressed bee immune systems. In addition to toxicity to bees, pesticides like neonicotinoids have been shown to also adversely affect birds, aquatic organisms and contaminate soil and waterways, and overall biodiversity.
Source: e News Park Forest, 24 October 2016
https://enewspf.com/2016/10/24/neonicotinoid-insecticide-exposure-reduc…
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