06
Apr
Pesticides and the Climate Crisis: Bumble Bee Behavior Thwarted by Temperature and Chemical Exposure
(Beyond Pesticides, April 6, 2023) A study published in Global Change Biology adds to research demonstrating that climate change can exacerbate the adverse impacts of pesticide exposure on managed and wild bees. Temperature can alter the sublethal effect pesticides, particularly the neonicotinoid (neonic) imidacloprid and the sulfoximine sulfoxaflor, have on bumble bee behavior tied to fitness and pollination services. Both an increase and decrease in temperature can cause diverging thermal responses in bumble bee behavior. However, increasing temperature bares more severe behavior abnormalities than cooler temperatures.
The pervasiveness of pesticide exposure combined with climate change threatens global species biodiversity. As has been widely reported, pollinators (such as bees, monarch butterflies, and bats) are a bellwether for environmental stress as individuals and as colonies. Pesticides intensify pollinators’ vulnerability to health risks (such as pathogens and parasites), with pesticide-contaminated conditions limiting colony productivity, growth, and survival. Now more than ever, people are changing their sentiment toward sustainability, with two-thirds of consumers stating the importance of limiting climate change impacts and 88 percent supporting greater pollution reduction. The globe is currently going through the Holocene Extinction, Earth’s 6th mass extinction, with one million species of plants and animals at risk. With the increasing rate of biodiversity loss, advocates say it is essential for government agencies to hold the pesticide industry accountable for the direct (i.e., excessive agrochemical use) and indirect (i.e., water pollution from runoff) impacts on ecosystems.
The study notes, “Our findings highlight the importance of multi-stressor studies to quantify threats to insects, which will help to improve dynamic evaluations of population tipping points and spatiotemporal risks to biodiversity across different climate regions.”
The study investigates six behaviors of bumblebees exposed to imidacloprid and sulfoxaflor at three different temperatures (21 ̊C/69.8 ̊F [Low], 27 ̊C /80.6 ̊F [Medium], 30 ̊C / 86 ̊F [High]). The behaviors under observation include: “1. Likelihood of being responsive; 2. Likelihood of movement; 3. Rates of walking; 4. Rate of food consumption; 4. Flight distance; and 5. Flight velocity.”
Of the six behaviors, imidacloprid significantly impacts the responsiveness, likelihood of movement, walking rate, and food consumption rate at lower temperatures and reduces flight distance by over 50 percent at higher temperatures. Sulfoxaflor impacts bumble bee walking rate at medium temperatures and reduces flight distance by 24 percent, but not as significantly as imidacloprid. With temperature predicted to increase, lead researcher from the Department of Life Sciences (Silwood Park) at Imperial College London, Richard Gill, Ph.D., highlights, “The drop-off in flight performance at the highest temperature suggests a ‘tipping point’ has been reached in the bees’ ability to tolerate the combined temperature and pesticide exposure. This seeming cliff-edge effect happens over the span of just three degrees, which changes our perception of pesticide risk dynamics given such temperature changes can commonly occur over the space of a day.”
The United Nations states that 80 percent of the 115 top global food crops depend on insect pollination, with one-third of all U.S. crops depending on pollinators, according to the U.S. Department of Agriculture (USDA). However, research finds that many insect populations, including managed and wild pollinators, are collapsing. Monarchs are near extinction, and commercial beekeepers continue to experience declines that are putting them out of business. The continued loss of mayflies and fireflies disrupts the foundation of many food chains. Additionally, the decline in many bird species has links to insect declines. Since the 1970s, three billion birds have vanished. Despite habitat fragmentation and climate change, extensive use of pesticides, like neonicotinoids, sulfoxaflor, pyrethroids, fipronil, and 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 cause similar or more severe impacts 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 the past decades, a lack of pollinators threatens food security and stability for current and future generations.
Additionally, the U.S. Geological Survey (USGS) routinely finds widespread pesticide contamination of surface waters throughout the U.S. Scientists warn that neonicotinoids and other pesticides pose a direct threat to both insect and non-insect wildlife, including birds, aquatic animals, and other wildlife, which absorb pesticide sprays and vapors through respiration, as well as ingestion via food. Industrial agriculture and its use of hazardous pesticides, particularly systemic insecticides like the neonicotinoid class, are harming insect life and biodiversity throughout the globe. Most animals on Earth are insects, which play a significant role in sustaining the ecosystem, despite their size. Insects found in nature preserves are consistently contaminated with over a dozen pesticides, calling into question the ability of these areas to function as refuges for threatened and endangered species. With rampant pesticide use and ubiquitous contamination, it is imperative that lawmakers and regulators embrace stronger measures to reverse the ominous trajectory society continues to follow, especially with the ongoing global insect apocalypse.
The wide range of temperatures in temperate regions can significantly impact bee health and survival more severely when combined with pesticide exposure, demonstrating synergistic (combined) effects on flight performance within a three-degree Celsius increase. However, the synergistic impacts of pesticides and climate change are not a new phenomenon. A 2023 U.S. Geological Survey (USGS) utilizing a climate and land use model confirms that recorded temperature during the warm seasons has a greater impact on bee declines, with a twofold increase in negative stressors. However, bees are not the only insects a risk of chemical exposure. Research published in 2017 highlighted a major red flag for insect populations worldwide, finding a 77 percent decline in German nature preserves of flying insect biomass. A systematic review of insect population decline studies published in 2019 found that 41% of insect species worldwide are declining. The declines of butterflies, wild bumblebees, and honey bees have links to hazardous pesticide use in conventional agricultural systems. Since 1990, roughly a quarter of the global insect population has been vanishing, according to research published in Science. This research finds worldwide trends in declines in terrestrial insect biomass to be nearly 1% each year (~9% each decade).
To mitigate the risks associated with chemical exposure from toxic pesticides, advocates say the manufacturing and use of pesticides need addressing, first and foremost. Global leaders should curtail the continued manufacturing of chemical pollutants that readily contaminate the environment. The U.S. Environmental Protection Agency (EPA) appears to discount threats like the insect apocalypse, evidenced by a 75% decline in insect abundance, threatening global ecosystems and food production that depends on animal pollination. If pesticide use and manufacturing are amplifying the impacts of the climate crisis, especially on vital pollinators, advocates argue that it is essential to incite change by enhancing pesticide policy and regulation that eliminate use.
Dr. Gill, concludes, “…[T]he frequency to which bees will be exposed to pesticides and extreme temperatures under climate change are predicted to increase. Our work can help to inform the right concentrations and application times of pesticides across different climatic regions of the world to help safeguard pollinators, such as bees.”
Ending toxic pesticide use can alleviate the harmful impacts of these chemicals on species and ecosystem health. Beyond Pesticides captured the bigger picture in its introduction to its 2017 National Pesticide Forum, Healthy Hives, Healthy Lives, Healthy Land: “Complex biological communities support life.” Learn more about the science and resources behind pesticides’ impact on pollinators, including bee pollinator decline, and take action against the use of pesticides. To find out more about what you can do to protect bees and other pollinators, check out information on the BEE Protective Campaign, pollinator-friendly landscapes, pollinator-friendly seeds, pesticide-free zones, bee-friendly habitats, and what you, or your state representative, can do to protect our pollinators. For more information on the insect apocalypse, see Beyond Pesticides’ article in the Pesticides and You journal, “Tracking Biodiversity: Study Cites Insect Extinction and Ecological Collapse.”
Additionally, the Intergovernmental Panel on Climate Change (IPCC) finds that agriculture, forestry, and other land use contributes about 23% of total net anthropogenic emissions of greenhouse gases, while organic production reduces greenhouse gas emissions and sequesters carbon in the soil. Learn more about the possibility of sequestering more than 100% of current annual CO2 emissions by switching to organic management practices by reading Regenerative Organic Agriculture and Climate Change: A Down-to-Earth Solution to Global Warming. For more information about organic food production, visit the Beyond Pesticides Keeping Organic Strong webpage. Learn more about the adverse health and environmental effects chemical-intensive farming poses for various crops and how eating organic produce reduces pesticide exposure. Buying, growing, and supporting organic agriculture eliminate the extensive use of pesticides in the environment. Organic land management eliminates the need for toxic agricultural pesticides. For more information on how organic is the right choice for consumers and the farmworkers who grow our food, see the Beyond Pesticides webpage, Health Benefits of Organic Agriculture.
Spring is around the corner, so get ready to grow your spring garden the organic way by Springing Into Action, pledging to eliminate toxic pesticide use.
All unattributed positions and opinions in this piece are those of Beyond Pesticides.
Source: Science Daily, Global Change Biology
