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According to a new study, wild bumblebees in Massachusetts could be threatened even by low levels of neonicotinoid pesticides in the environment.
Researchers at the Polytechnic Institute of Worcester have discovered that royal drones and drones, essential for the formation of bee colonies, are particularly vulnerable to neonicotinoids. The study, published in the open access scientific journal PLOS One, is the first comprehensive overview of the impact of these pesticides on queen and male bees.
"Our bumblebees and other native pollinators will disappear as will our native flowering plants and the animals that use them for food, shelter and nesting," said co-author Robert Gegear. "We need to understand all the factors that contribute to the decline of wild bees, but there is growing evidence against neonicotinoids in agricultural and urban areas because neonicotinoids are easily transferred from the soil to the nectar and pollen of wildflowers that grow there. and may persist in the environment for extended periods of time, they represent a potential hazard to wild bumblebees at all stages of their annual life cycle. "
Gegear, an assistant professor of biology and biotechnology, wrote this study with Melissa Mobley, PhD candidate at WPI.
Each autumn, newly introduced male and queen bees leave their wild colonies to mate. The queens then find a place where they can survive in the winter, as their colonies die of cold. In the spring, they emerge, nest and lay, creating a new colony.
It is this delicate cycle that can be threatened by neonicotinoids, according to the study. Gegear and Mobley's research has found that while worker bees can survive the low bee levels that bees can encounter in the real world, the mortality rates of men and queens are higher.
Previous research on bees has escaped potential harm, primarily focused on the effect of neonicotinoids on man-made honey bees, intended for crop pollination, Gegear said.
"All these vulnerabilities are forgotten when you focus on bees in an agricultural context," Gegear said in an interview.
The fate of American bees became a source of national concern in 2006, when beekeepers and scientists noticed the widespread and unexplained loss of honey bee colonies – known as the Colony Collapse Disorder. According to the Bee Informed Partnership, a USDA-funded research coalition, managed honeybee colonies recorded losses of more than 30% during the winters of 2006 and 2007, well above rates acceptable by about 15%.
Loss rates dropped in the mid-twenties but remained above normal. And in 2017-2018, rates have again risen by about 30%, according to Bee Informed's preliminary results.
The mysterious nature of the colony disappearances made headlines and sparked the outcry from environmental groups, who warned that the loss of pollinating bees could pose a threat to the US agricultural ecosystem.
The researchers posed a number of theories about the cause of the colony collapse disorder. While pests and diseases are largely responsible for annual bee deaths, researchers wondered if a new class of insecticides, the neonicitinoids, was causing unexpected damage to bee populations .
The "Beepocalypse" warned by the media out of breath did not succeed for the bees. Globally managed honeybee populations have rebounded since the mid-2000s, largely as a result of beekeepers' efforts to deal with continued loss of colonies.
But while the colony collapse disorder has largely subsided, the death rate remains high, Science News reported earlier this year. And this recovery has only been measured for bees kept by humans, leaving uncertain the fate of wild bees.
Wild bees – bumblebees and other species that pollinate native plants, rather than crops grown – are at the center of Gegear and Mobley's research.
Problems facing bees are an economic rather than an existential problem, Gegear said, with the most likely negative effects being higher food prices as the cost of pollination increases for farmers.
But for some of Massachusetts' native bees, diebacks could lead to extinction. Geager, who has personally investigated bee populations in much of the state, has discovered that two of the 11 species of honeybees historically living in Massachusetts are probably no longer present. Four others are in decline, the others are stable or increasing.
And while farmers are concerned about the sheer number of workers available to pollinate crops, the state's environment has more specific needs, Gegear said. Wild bumblebees are a key species whose pollination habits preserve ecological diversity. And disturbances of these species could ricochet the food chain, affecting herbivores that feed on pollinators and predators that eat these animals.
"There are cascading negative effects that affect the entire ecosystem," Gegear said. "I do not think people realize that when we see birds disappearing, this could ultimately be attributed to pollinators."
Gegear views his study as evidence of the actual adverse effects of neonicotinoids, claiming that, used on crops, lawns or flowerbeds, the pesticide can remain in the soil for years and contaminate wildflowers used by wild bees .
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