“This is odd, as it’s a very common mitigation measure and not overly hard to test.”

Are Pesticide Safety Measures Truly Bee-friendly? Pesticide Mitigation Measures Under Microscope for Bee Protection

Responsible pesticide usage involves minimizing adverse environmental impacts, with a particular focus on safeguarding bees and other pollinators. However, a new study reveals that many commonly employed methods to mitigate the impact of pesticides on bees, including some recommendations on product labels, are not adequately supported by scientific research.

The researchers behind this study argue that more rigorous testing is necessary to determine which measures truly safeguard bees and which ones rely too heavily on conventional wisdom. They have shared their analysis in a report published in the Journal of Economic Entomology.

Growers are advised to adopt various “mitigation measures” during pesticide applications to protect bees, such as spraying at night, using specific sprayer nozzles, or maintaining buffer zones.

Edward Straw, Ph.D., a postdoctoral researcher in the School of Agriculture and Food Science at University College Dublin (UCD) in Ireland and the lead author of the study, emphasizes, “It takes time, money, and effort to follow these rules, so if they are not actually helpful, they are a waste of time. If they are helpful, though, they could be applied more widely, to protect bees further.”

Straw and colleague Dara Stanley, Ph.D., assistant professor in applied entomology at UCD, reviewed published, peer-reviewed research to identify studies evaluating the effectiveness of different mitigation measures in reducing the impact of pesticides on bees. Out of the wide range of measures studied, they found only 34 studies that met their criteria, primarily focused on a single type of bee.

“Almost all research was centered around protecting honey bees. However, honey bees are a managed species that is not endangered,” explains Straw. “When we try to protect bees, we really want to be protecting wild, unmanaged bee species, as these are the species which are in decline.”

Only a few mitigation measures had been tested in more than one or two studies, and the testing methods varied. For example, some studies examined direct overspray, while others assessed long-term pesticide residues. Surprisingly, only three studies in Straw and Stanley’s review evaluated measures frequently mentioned on pesticide labels.

Straw points out, “Least researched was testing on how you time a pesticide spray, be that time of day or time of year. There’s good reason to believe that if you change when you spray, you could avoid peaks in bee activity. Yet surprisingly no one has really researched if this idea works. This is odd, as it’s a very common mitigation measure and not overly hard to test.”

Other mitigation measures examined in existing studies included the application techniques of pesticides (e.g., spray parameters or planting methods for pesticide-coated seeds), buffer zones, removal of flowering weeds before spraying, direct interventions for managed bees (e.g., relocating or covering colonies), and applying pesticides only under specific weather conditions or during certain crop stages.

The most extensively studied mitigation measure (12 studies) was the use of repellent additives in pesticide sprays, which discourage bees from approaching recently sprayed crops. Several compounds have shown promise in laboratory testing, but all 12 studies focused solely on honey bees, and no tests were conducted with the additives combined with pesticides—only in isolation.

“It is an interesting idea, but it is not yet ready to be used,” adds Straw. “It would need to be tested on a diversity of bee and insect species, as if it is only repellent to one or two species, all the other bees would still be exposed to the pesticide.”

In summary, Straw and Stanley assert that too much relies on weakly supported bee-protective measures. Bees play a critical role in both natural ecosystems and agriculture, and assuming the effectiveness of mitigation measures can influence decisions regarding pesticide authorization. They stress the imperative need for rigorous scientific evaluation of these measures.

“The main limitation is that these studies need to be big, well-funded pieces of research. To test changes to how a pesticide is applied to a crop, you need to have a crop, a pesticide sprayer, and someone licensed to spray. All of that is expensive and time consuming, making it out of reach for most scientists,” explains Straw.

Nevertheless, if such research can be conducted, there is reason to believe that it will have immediate positive impacts. In a previous study published earlier this year by Straw and Stanely, high compliance with pesticide regulations and guidelines among farmers was observed in an anonymous survey.

“We know that these mitigation measures are being followed,” adds Straw. “We just do not know if they are helpful yet.”

Source: 10.1093/jee/toad118

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