09
Oct
New Insecticides Escalate Indiscriminate Harm to All Organisms
(Beyond Pesticides, October 9, 2020) A new study demonstrates that emerging “novel” insecticides can cause significant, sublethal harm to beneficial organisms at typical “real life” exposure levels. As neonicotinoid insecticides have come under fire for their terrible impacts on a broad variety of beneficial insects — including their major contributions to the decline of critical pollinators — more such “novel” pesticides are being brought to market in response. The study results, the co-authors say, “confirm that bans on neonicotinoid use will only protect beneficial insects if paired with significant changes to the agrochemical regulatory process. A failure to modify the regulatory process will result in a continued decline of beneficial insects and the ecosystem services on which global food production relies.” Beyond Pesticides would add that the study outcome points, yet again, to the grave recklessness of the pervasive “addiction” to chemical pesticides in agriculture. The solution to this chemical morass is known, doable, and scalable: a transition to organic, regenerative agricultural practices that get everyone off the “toxic treadmill.”
Neonicotinoid pesticides (neonics) are the class of chemical pesticides most commonly used worldwide, both on crops and as seed treatments. They are systemic, meaning they infiltrate all tissues of a plant, and are environmentally persistent (in plants and in soils); they can also contaminate freshwater sources. As the study paper notes, “Field-realistic applications of neonicotinoids can have significant sub-lethal impacts on beneficial insects, with knock-on effects on ecosystem services. This has resulted in bans and restriction on neonicotinoid use globally, most notably in the European Union.” Here in the states, the Environmental Protection Agency (EPA) has permitted broad use of neonics, and is currently reviewing all neonicotinoid pesticides. This study addresses the substance of one of Beyond Pesticides’ critiques of EPA’s regulatory failures on neonics: the insufficiency of the agency’s risk assessment procedures in accounting for sublethal impacts of the compounds.
The study’s researchers discovered that two novel pesticides, flupyradifurone and sulfoxaflor, share the same mode of action as neonics, although they are (nominally) from different chemical classes than are neonics. This research focused on these two compounds because, given that both Dow Agrochemicals’ sulfoxaflor (classified as a butanolide) and Bayer CropScience’s flupyradifurone (classified as a sulfoximine) are somewhat effective on pest species that resist neonics, these novel insecticides are considered to be candidates to replace neonics in geographic regions with significant levels of neonic resistance, and where neonic compounds are restricted or banned.
Sulfoxaflor and flupyradifurone, like neonics, are systemic insecticides. Flupyradifurone can persist in soils for months or years, whereas sulfoxaflor’s half-life in soil is two or three days. Research data reviewed by the subject study suggest that beneficial insects will be exposed to these compounds at relatively high concentrations in agricultural environments. This can happen during spray applications to seeds or fields, or indirectly, when insects (or birds or other organisms) feed on such seeds, as well as on plant tissue, pollen, or nectar.
The research was conducted by Harry Siviter, PhD and Felicity Muth, PhD of the Department of Integrative Biology at the University of Texas at Austin; the subsequent paper was published by the Proceedings of the Royal Society B: Biological Sciences in late September, 2020. The researchers’ meta-analysis extracted useful data from 19 of the 26 studies they reviewed, and paid particular attention to impacts on beneficial insects — dominantly, on bee species — and evaluated outcomes related to organism mortality, reproduction, and behavior. In addition, the scientists evaluated impacts on predator species, such as such as wasps, lacewings, and beetles.
The researchers learned that flupyradifurone can have lethal impacts at field-realistic levels, with some kinds of bees being more vulnerable than others; further, and unsurprisingly, exposures to the compound were more likely to be harmful in combination with other environmental stressors, such as poor nutrition, pathogens, or other agricultural chemicals. The co-authors note that the lethality of sulfoxaflor, which is toxic to bees at high levels of exposure, may vary at lower doses, depending on the interactions with other environmental factors. But given certain combinations of those variables, sulfoxaflor exposures at field-realistic levels appear to increase bee mortality.
The study also shows that sulfoxaflor has negative impacts on bee reproduction similar to those of neonics, particularly reduced reproduction (egg laying) and poor larval development, and that flupyradifurone exposures impair bees’ flight behavior, foraging success, and bodily temperature regulation. Findings included impacts on beneficial predators, including a huge increase (40–60%) in the mortality of flupyradifurone-exposed rove beetles, and 100% mortality of exposed insidious flower bugs (also known as pirate beetles).
Sulfoxaflor shows harmful effects on many taxa: hymenoptera (bees, wasps, ants), coleoptera (beetles), and hemiptera (cicadas, aphids, planthoppers, leafhoppers). At field-realistic exposure levels, for example, the parasitic activity of some wasps was reduced, and mortality increased; lacewings showed increased mortality and reduced fertility; ladybug larvae suffered 100% mortality; and pirate beetle mortality was 96% within 24 hours of exposure to sufoxaflor.
Both compounds, which act on the nervous systems of organisms, have been registered for use throughout the European Union (EU), where use of neonics is significantly constrained. EPA first registered sulfoxaflor in 2013, and amended the registration in 2016 to create some limitations on its use. In 2015 it issued a cancellation order for all uses of sulfoxaflor, but then granted some emergency exemptions for its use. In 2019, EPA effectively restored all previously registered uses, functionally “canceling the cancellation,” and even expanded uses of the chemical insecticide.
EPA registered flupyradifurone for use in 2015, after which the Pesticide Research Institute commented, “Despite the safety claims in the registration notice, the available data suggest that flupyradifurone may possess many of the undesirable attributes associated with neonicotinoids.” Indeed, in June 2020, Beyond Pesticides wrote about outcomes of an Oregon State University study that showed that both “sulfoxaflor and flupyradifurone . . . were found to increase apoptosis (cell death) and increase oxidative stress in exposed honey bees. The study . . . [paper writes], ‘With the recent Environmental Protection Agency (EPA) approval for use of both flupyradifurone and sulfoxaflor, and with the growing concern regarding pollinator health, it is important to better understand any potential negative impacts (especially sub-lethal) of these pesticides on bees.’ However, this statement begs the question ‘why [were] these two new bee-toxic pesticides . . . approved by EPA in the first place.’”
The authors conclude: “Novel insecticides have significant sublethal impacts on beneficial insects, demonstrating that, in its current form, the regulatory process does not safeguard beneficial insects from detrimental effects of agrochemical use. Thus, simply replacing neonicotinoids with novel chemical insecticides is unlikely to reduce negative consequences on beneficial insects.” In their paper, the researchers make several recommendations EPA should include in its regulation of pesticides:
• mandatory assessments of sublethal effects on wild bees
- assessments of novel insecticides on non-bee beneficial insects
- assessments of interactions between agrochemicals and other anthropogenic stressors
They conclude: “Flupyradifurone and sulfoxaflor can have significant negative sub-lethal impacts on beneficial insects, confirming that (i) in its current form, the regulatory process is failing to detect the sub-lethal but significant negative impacts of novel insecticides on beneficial insects, and (ii) bans on commonly used insecticides will only protect beneficial insects if replacement insecticides do not have similar sub-lethal impacts. Whether an insecticide will ever exist that controls pest species while having no impact on beneficial insects is unknown. However, a failure to modify the regulatory process and consider the sub-lethal impacts of novel insecticides will result in the continuing cycle of insecticides being licensed for use without a full understanding of their potential impact on beneficial insects.”
These are valid conclusions and recommendations. Yet they also seek to “modify” the prevailing paradigm that synthetic and toxic chemical pesticides can represent any kind of “safe” approach to agricultural and other land management problems. Beyond Pesticides has — for decades — written about the failing of this paradigm and the institutions that execute its activities, and pointed the way to precautionary, safe, and nontoxic approaches to all manner of pest problems. What the public lives with, and eats and breathes and drinks from, is a dominant agricultural system that has become terribly dependent on these chemical inputs (pesticides and synthetic fertilizers, primarily) that cause documented harms to human, and to wildlife and ecosystem, health.
It is time to get off the “toxic treadmill” that has the agrochemical industry — in response to the burgeoning problem of resistance to pesticides, or to “bad press” on a pesticide, or occasionally, to actual harms — going back to its laboratories to search for more “novel” or tweaked chemical compounds to throw at the problem. The subject study evidences the folly of this approach, as Beyond Pesticides wrote back in June: “This process is familiar and frustrating to those who continue to fight against the decline of pollinators: the chemical industry introduces and EPA approves new toxic pesticides marketed as ‘safer’ to the specific problem caused by its older products, only to find out through independent and academic research that the problem is not solved in the least.”
This is an entropic and unsustainable approach, and must be replaced by organic and regenerative systems that are, by their very nature, precautionary and therefore, protective of health and environment. Join Beyond Pesticides to support the voices of advocates, and to bring critical information to farmers, land managers, and policy makers about how to transition off of the toxic treadmill and adopt genuinely protective and effective practices.
Source: https://royalsocietypublishing.org/doi/10.1098/rspb.2020.1265
All unattributed positions and opinions in this piece are those of Beyond Pesticides.
