05
Nov
Pesticides Impair Bees’ Immune Function, Pure Pollen Diet Has Positive Effect
(Beyond Pesticides, November 5, 2014) New research from Pennsylvania State University reports that pesticides cause large changes in the expression of genes involved in detoxification, immunity and nutrition-sensing in bees, adding to previous research that has found that pesticides compromise bee immune function. This research also finds that bees with a diet of natural, high quality pollen exhibit greater resistance to pesticides’ deleterious effects than bees on an artificial diet.
The new study, “Genomic analysis of the interaction between pesticide exposure and nutrition in honey bees (Apis mellifera),” finds that pesticide exposure can impact the expression of genes that are sensitive to diet and nutrition. The researchers, upon feeding honey bees either the miticidal pesticides, coumaphos or fluvalinate, for a period of seven days, noticed significant changes in 1,118 transcripts – or strands of RNA – in the experimental group. The transcripts include genes involved in detoxification, immunity, and nutrition.
The authors report that there is substantial overlap in responses to pesticides and pollen-containing diets at the genetic level. Subsequent analyses demonstrate that pollen-based diets reduce the honey bees’ susceptibility to pesticide stress verses an artificial diet – e.g. a soy protein or no protein diet. Thus, the researchers note that providing honey bees and other pollinators with high quality nutrition may improve resistance to pesticides. Specifically, the team fed the bees these diets while simultaneously feeding them a lethal dose of the pesticide, chlorpyrifos. Those fed a pollen-based diet exhibit reduced sensitivity to chlorpyrifos, compared to the bees fed an artificial diet, demonstrating that diet significantly impacts how long bees can survive when given a lethal dose of a pesticide.
“This interaction between pesticide exposure and nutrition is likely what’s at play in our finding that feeding bees a complex diet of pollen —their natural diet— makes them significantly more resistant to lethal doses of a pesticide than feeding them a more simple, artificial diet,” said Daniel Schmehl, postdoctoral researcher at Penn State and lead author of the study.
Scientific studies have been focusing on the role of pesticides in the decline of bee populations worldwide. One pesticide class in particular, neonicotinoids, has been singled out as a main contributing factor. Pesticides like neonicotinoids have been shown to impair bees’ ability to learn, to find their way back to the hive, to collect food, to produce new queens, and to maintain a healthy immune system. Studies have found that bees are exposed to neonicotinoid pesticides through pollen and nectar, as well as via contaminated soil, dust, and water. Recent studies have found that near infinitesimal exposures to neonicotinoids cause a reduction in the amount of pollen bees are able to collect for their colony. Researchers found that the effects of neonicotinoid intoxication persist for a least a month after exposure, underscoring the long-term damage these chemicals can cause to bee colonies. Another study shows two widely used neonicotinoids significantly harm honey bee colonies over the winter, especially during colder winters. Read the report No longer a Big Mystery.
This past summer, the “Worldwide Integrated Assessment (WIA)” ””undertaken by the Task Force on Systemic Pesticides, which reviewed over 800 studies ”” documented significant harms to bees and ecosystems. The analysis focuses not only on impacts to particular organisms and habitats, but also on biodiversity and ecosystem impacts, taking a holistic view of pesticide effects. The task force is calling for new, dramatic restrictions on bee-harming pesticides in the U.S. and beyond. The report finds that the current regulatory system has failed to consider the full range of pesticide effects.
The neonicotinoids, especially imidacloprid, clothianidin, thiamethoxam, and dinotefuran first came into heavy use in the mid-2000s. At the same time, widespread cases of bee and colony losses started to be reported at rates not experienced before. Over the past few years, Beyond Pesticides, other advocacy groups, and beekeepers have filed legal petitions and lawsuits with EPA, calling on the agency to suspend the use of neonicotinoids. Yet, years later the agency has refused and indicated it will review the registration status of the neonicotinoids by 2018. The White House issued a Presidential Memorandum on pollinator health to the heads of federal agencies requiring action to “reverse pollinator losses and help restore populations to healthy levels.” The President is directing agencies to establish a Pollinator Health Task Force, and to develop a National Pollinator Health Strategy, including a Pollinator Research Action Plan within 180 days. The memorandum recognizes the severe losses in the populations of the nation’s pollinators, including honey bees, wild bees, monarch butterflies, and others and the impact to the agricultural economy. However, the White House recently announced that it would miss the deadline to provide a pollinator health strategy.
Meanwhile, the White House Council on Environmental Quality (CEQ) announced new guidelines for federal agencies to incorporate pollinator friendly practices at federal facilities and on federal lands. Critical to pollinator health within these guidelines is a requirement that agencies should “[a]cquire seeds and plants from nurseries that do not treat their plants with systemic insecticides.” The document also states that, “Chemical controls that can adversely affect pollinator populations should not be applied in pollinator habitats. This includes herbicides, broad spectrum contact and systemic insecticides, and some fungicides.” In keeping with the recognition that pollinators need protecting from pesticides, the U.S. Fish and Wildlife Service’s announced this summer that the agency will eliminate neonicotinoid use on National Wildlife Refuges.
For more information on how to improve pollinator health and habitat see the BEE Protective webpage, where you can find the Pollinator Friendly Seed and Nursery Directory, which lists sources of seeds and plant starts that are safe for bees and not poisoned with neonicotinoids or other pesticides. Join efforts to protect pollinators and educate your community about the importance of these creatures at BEE Protective.
Source: Science Daily, Nature World News
All unattributed positions and opinions in this piece are those of Beyond Pesticides.
