(Beyond Pesticides, September 13, 2023) A study published in Global Change Biology finds climate change increases beesâ€™ sensitivity to pesticide exposure,Â impairing the pollinatorsâ€™ ability to respond to light (Ultra-Violet [UV] stimuli), reducing floral syrup consumption, and lessening longevity (length of life) up to 70 percent. Notably, the reduction in floral syrup consumption indicates nutritional stress that further impacts bee species’ fecundity (productiveness), driving bee declines. Unless more is done to combat the climate crisis, the current global warming scenario increasing beesâ€™ sensitivity to pesticide exposure will continue to threaten all pollinator health.
The pervasiveness of pesticide exposure, combined with climate change, threatens global species biodiversity. As has been widely reported,Â pollinatorsÂ (such as bees, monarch butterflies, and bats) are a bellwether for environmental stress as individuals and as colonies. Pesticides intensify pollinatorsâ€™ vulnerability to health risks (such as pathogens and parasites), with pesticide-contaminated conditions limitingÂ colony productivity, growth, and survival. The globe is currently going through theÂ Holocene Extinction, Earthâ€™s 6th mass extinction, with one million species of plants and animals at risk, including pollinators. Pollinator declines directly affect the environment, society, and the economy. Without pollinators, many agricultural and nonagricultural plant species will decline or cease to exist as U.S. pollinator declines, particularly among native wild bees,Â depress crop yields.Â In turn, the economy will take a hit since much of the economy (65%) depends upon the strength of the agricultural sector. As theÂ science shows, pesticides are one of the most significant stressors for pollinators. Additionally, theÂ devastating impacts of pesticidesÂ on bees and other pollinators and the larger context of what scientists have called the â€śinsect apocalypse.â€ť In a world where the climate crisis shows no sign of abating, scientists have concluded that the globe cannot afford to continue to subject its critically important wild insects to these combined threats. Therefore, studies like this emphasize the need to consider how many stressors impact the survivability of essential species.
The study notes, â€śOur findings indicate that ongoing global warming may exacerbate the impact of pesticides on bee health and compromise bee reproductive success, with potentially important consequences on population dynamics. The magnitude of these impacts will depend on our ability to reduce the dependence of agriculture on pesticides and on the extent to which bee populations can adjust to the new climate scenario through adaptation and/or phenotypic plasticity.â€ť
The study analyzes the synergistic (combined) effects of global warming and sublethal insecticide exposure in the solitary beeÂ (European orchard bee/horned mason bee) Osmia cornuta. Using a simulated wintering treatment, the researchers exposed O. cornutaÂ females to three different temperature scenario models: current scenario (2007â€“2012 temperatures), near-future (2021â€“2050 projected temperatures), and distant future (2051â€“2080). During the spring, the bees emerged, and researchers examined the pollinatorâ€™s sensitivity to a formulation of sulfoxaflor insecticide at two sublethal doses. Lastly, the researchers measured the combined impact of the various temperature scenarios and sublethal insecticide exposure on the phototactic response (response to light stimuli), feeding behavior, and longevity. The results find the temperature treatment has a profound effect on body weight, as increasing temperatures led to decreasing body weight in bees. This is concerning as body fat plays a crucial role in chemical detoxification. Although the temperature has little impact on phototactic response or feeding behavior, bees exposed to the warmest temperature scenario have shorter lifespans. Insecticide exposure negatively affects the phototactic response, feed behavior, and lifespan of bees, especially at higher doses. The combination of the warmest temperature and high insecticide exposure decreased longevity in bees by 70 percent. Thus, warming temperatures and insecticide exposure represent two significant drivers of bee decline that have important implications for the future of ecosystem services.
The scientific literature demonstrates pesticidesâ€™ long history of adverse environmental effects, primarily onÂ wildlife,Â biodiversity, andÂ human health. Most notably, pesticides are immensely harmful to pollinators. Over the lastÂ decade and a half, increasing scientific evidence shows a clear connection between the role of pesticides in the decline of honey bees and wild pollinators (e.g., wild bees, butterflies, beetles, birds, bats, etc.). For instance, monarchs are near extinction, andÂ commercial beekeepers continue to experience declinesÂ that are putting them out of business. TheÂ continued loss of mayfliesÂ and firefliesÂ disrupts the foundation of many food chains. Additionally, the reduction in many bird species has links to insect declines. Pollinatorsâ€™ decline directly affects the environment, society, and the economy. TheÂ United NationsÂ states thatÂ 80 percent of the 115Â top global food crops depend on insect pollination, withÂ one-thirdÂ of all U.S. crops depending on pollinators, according to the U.S. Department of Agriculture (USDA). Globally, the production of crops dependent on pollinators is worth betweenÂ $253 and $577 billionÂ yearly. Hence, pesticide use fails to support the current ecosystem, decreasing agricultural and economic productivity and social (human/animal) and environmental well-being.
This study adds to the growing body of research supporting the adverse effects climate change and pesticide exposure have on pollinators, as these stressors already affect bee population dynamics. Warming temperatures alter the body composition of bees, reducing body fats. Bees are ectotherms and thus highly dependent on environmental temperatures for adequate growth, development, and reproduction, making these essential pollinators particularly vulnerable to global warming. Nevertheless, climate change and extensive use of pesticides, likeÂ neonicotinoids,Â sulfoxaflor,Â pyrethroids,Â fipronil, andÂ organophosphates, increase the potential risk and indiscriminate threat to all insects. Research shows that residues from neonicotinoids (including seed treatments) and sulfoxaflor accumulate and translocate to pollen and nectar of treated plants. Pyrethroids and fipronil impair bee learning, development, and behavioral function, reducing survivability and colony fitness. However, inert ingredients in these products causeÂ similar or more severe impactsÂ on insect populations, such as disruption in bee learning behavior through exposure to low doses of surfactants. With the global reliance on pollinator-dependent crops increasing over theÂ past decades, a lack of pollinators threatens food security and stability for current and future generations. It is increasingly clear that humanityâ€™s continued use of fossil fuels and fossil fuel-derived pesticides are the core drivers of pollinator declines. These are not siloed but interacting crises, creating a positive feedback loop and compounding one anotherâ€™s harmful effects. Despite these stressors, alternatives are within reach.
Pollinator protection policies need improvements to safeguard not only all pollinators but also the crops they pollinate. Beyond Pesticides holds that we must move beyond pesticide reduction to organic transition and commit to toxic pesticide elimination in our agricultural system to prevent the crop loss presented in this study. Pesticide elimination can alleviate the effect of these toxic chemicals on humans and wildlife. With EPA failing to take the most basic steps to protect declining pollinators, it is up to concerned residents to engage in state and community action and demand change. Moreover, the government should pass policies that eliminate a broad range of pesticides by promoting organic land management. Habitat in and of itself may assist, but it must be free of pesticides to protect wild pollinator populations. To protect wild bees and other pollinators, check outÂ what you can doÂ by usingÂ pollinator-friendly landscapesÂ andÂ pollinator-friendly seeds, engaging in organic gardening and landscaping, and supportingÂ organic agricultureÂ through purchasing decisions. Learn more about theÂ scienceÂ andÂ resourcesÂ behind the adverse effects of pesticides on pollinators andÂ take action againstÂ the use of pesticides.Â Buying,Â growing, and supporting organic will help eliminate the extensive use of pesticides in the environment. Organic land management andÂ regenerative organic agricultureÂ eliminate the need for toxic agricultural pesticides. For more information on the organic choice, see the Beyond Pesticides webpages,Â Health Benefits of Organic Agriculture,Â Lawns and Landscapes, andÂ Parks for a Sustainable Future.Â
Learn more by registering for the virtual 40thÂ National Forum Series,Â Forging a Future with Nature: The Existential Challenge to end petrochemical pesticide and fertilizer use, starting on September 14, 2023. Go toÂ the Forum website. Meet David Goulson, PhDâ€”preeminent authority on bees, pollinators, and ecosystems; author of Silent Earth, researcher, and professor at the University of Sussexâ€”at the Forum! And, learn from AndrĂ© Leu, PhD, director of Regeneration International, organic farmer, and author, about organic regenerative land management practices to protect community health, the environment, and the planet.
All unattributed positions and opinions in this piece are those of Beyond Pesticides.
Source:Â Global Change Biology