03
Jan
Biodiversity Threatened by Pesticide Drift, Study Finds; Organic Agriculture Cited as a Holistic Solution
(Beyond Pesticides, January 3, 2025) Pesticides that are sprayed and become airborne significantly disrupt ecological balances and affect nontarget species that are crucial for maintaining biodiversity, according to an article in Environmental Pollution. In this review of studies throughout countries in North and South America, Europe, and Asia, among others, researchers from Germany, Norway, the United Kingdom, and Poland reinforce the science about pesticides’ direct effect on species and the cascading effects of pesticide drift through various trophic levels within food webs that lead to overall devasting population effects.
This study “addresses the interconnectedness of these impacts and illustrates the complex threats that pesticide drift poses to biodiversity across multiple ecosystems,†the researchers state. They continue: “Impacts include reduced reproductive rates, changes in growth, development, and/or behavior, modification of diversity or community organization, disruption of food webs, and declines of important species. Pesticides disrupt the delicate balance between species that define a functioning ecosystem. Impacts can be local, transnational, or even continental.â€
Pesticide drift threatens beneficial species and subsequently the entire agricultural system. The process of pesticide drift, “in which up to 25% of applied pesticides are carried by air currents, can transport chemicals over hundreds or even thousands of kilometers,†the authors state. Other research has found that less than .1% of pesticides applied to crops reach the target pest. Drift rates vary due to a series of factors including temperature, wind speed, humidity, and soil type.
“The overuse of synthetic pesticides has unintentionally contaminated unintended areas, harmed non-target species and disrupted ecosystems that support agricultural productivity,†the researchers note. Pesticide drift “exposes a wide range of nontarget living organisms such as beneficial insects, birds, and other animals that live near to/or far from the incurred areas.†Drift exposure upsets the intricate balance of the ecosystem and reduces the ability of beneficial species to support agriculture. This underlines the broader environmental impacts that must be “carefully managed to preserve the ecological equilibrium on which agriculture ultimately depends,†the authors highlight.
Biodiversity is essential for ecological stability and function, as well as to ensure food security. The current biodiversity crisis, however, is perpetuated by the use of pesticides in agriculture. “Evidence shows that pesticides are driving severe biodiversity declines, often acting in concert with additional stressors,†the researchers postulate. They continue: “Herbicides, particularly glyphosate, dicamba, and 2,4-D sprays, have caused significant damage to many non-target plant species… Milkweed, a plant essential to monarch butterflies, often suffers glyphosate drift from farm areas. The resulting decline in milkweed plants has been one of the contributing factors to declining monarch populations since this plant helps in the growth and development of caterpillar stages of life during its life cycle.†(See more on monarch butterfly declines here and how to help protect this species here.)
Pesticide drift greatly impacts insect diversity, contributing to the “insect apocalypse†that not only affects primary producers and pollinators but a wide range of other species throughout the food web. As the authors share: “Some field studies have observed that, as plant diversity declines due to herbicide drift, so does the diversity of herbivores and predators and results in less balanced and more often pest-prone ecosystems. Thus, even though herbicides, insecticides, and fungicides target different organisms, their combined effects across multiple trophic levels can result in overall ecosystem destabilization.â€
Microorganisms within the soil are essential to many ecosystem functions, such as nutrient cycling, decomposition, and overall soil health. When soil biota are exposed to pesticides, particularly through spray drift and runoff, entire ecosystems can be threatened. “Spray drift is a primary pathway through which environmental microbes encounter pesticides,†the researchers say. “The effects of pesticides on microbial communities and their diversity include biomass reduction, growth disturbance, shifts in microbial community structure, and respiratory problems.â€
Pesticide drift is also of great concern for bodies of water and the aquatic species within them. One study in California reveals that pesticide drift has polluted more than 10% of streams in several regions. (See more on the effects of pesticides on aquatic organisms here and here.)
The widespread occurrence of pesticide drift is of global concern. “Detectable levels of pesticides in pristine regions, such as remote parts of Brazil, illustrate how atmospheric transport can disseminate the chemicals long distances from their original site of application and therefore contaminate regions with little or no direct use of pesticides,†the authors state. Detected pesticides in these areas include herbicides, insecticides, and fungicides. This diversity underlines the complex mixture of chemicals present in the atmosphere throughout various regions.
Current risk assessments, particularly through the U.S. Environmental Protection Agency (EPA), fail to address the impacts of pesticides on ecosystem functions and biodiversity, especially concerning pesticide drift for nontarget organisms. The authors share: “Pesticide regulation is based, to a great extent, on the paradigm of ‘presumed safe until proven hazardous.’ That is, pesticides are generally approved for marketing based on available determinations of safety and only subsequently restricted or removed from the marketplace when evidence develops to show that they present significant risks. EPA, for instance, is mostly very reluctant to ban or put any limits on pesticides until substantial evidence of the damage caused can be presented.†(See more on EPA failures to protect the environment and public health here, here, here, here, here, and here.) The agency has ignored studies going back decades in making exposure calculations in the registration of pesticides, whether it is direct pesticide drift or pesticides carried in fog.
“New research has shown that even when new evidence showed a risk in its use, including crop damage and health effects, the EPA has allowed the continued use of pesticides known for their environmental and health hazards, such as dicamba,†the researchers note. “Regulations must be able to better protect ecosystems and human health by requiring consideration of long-term effects before the wide acceptance of pesticides.â€
Not only would more accurate risk assessments more fully characterize the cumulative impacts of pesticide drift for all potentially impacted species, but holistic solutions, if implemented, would better protect health and the environment. As the authors state, “[O]rganic agriculture completely prohibits the use of pesticides, it can be considered one solution to reducing the problems of pesticide drift.†To preserve biodiversity for future generations and to support agricultural systems that we depend on for food security, organic land management is an available, economically viable, and profitable option, which is also climate-friendly.
Organic as a solution ensures that soil health is prioritized and that the health of all organisms is protected. Learn more about the benefits of organic agriculture here and here, and take action to have your voice heard on governmental actions that are harmful to the environment and public and worker health, increase overall pesticide use, or undermine the advancement of organic, sustainable, and regenerative practices and policies.
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All unattributed positions and opinions in this piece are those of Beyond Pesticides.
Source:
Albaseer, S. et al. (2024) Beyond the field: How pesticide drift endangers biodiversity, Environmental Pollution. Available at: https://www.sciencedirect.com/science/article/pii/S0269749124022437.
