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The long-term impact of a next-generation pesticide on bees

Our new research demonstrates the risks caused by a common pesticide on bee health and the limitations of risk assessments

Flupyradifurone is a next-generation ‘bee safe’ pesticide that has the same systemic properties and mode of action of neonicotinoids. Although flupyradifurone was authorised for use on crops with actively foraging bees and can contaminate their food for five months, its safety was only tested with limited short-term trials (10-day).

In this recent work, published in Communications biology, Tosi and colleagues performed a large, multinational experiment on honey bees, encompassing multiple subspecies, to assess the short- and long-term effects of a next-generation pesticide, flupyradifurone, on this key pollinator species.

Their research demonstrates that this “bee safe” pesticide impairs survival and behaviour at real-world exposure levels.

The increased use of pesticides is a major cause of reduced bee health and insect biodiversity and therefore threatens pollination in natural and agricultural ecosystems. To address this issue, Tosi and his colleagues therefore assessed the long-term effects of new pesticide, flupyradifurone, that is marketed as relatively “bee safe.” Seven laboratories located in six countries in Europe and North America participated using the same protocol and exposed multiple subspecies of honey bees to a range of field-realistic flupyradifurone levels to obtain lethal and sublethal information on their health and risk assessment.

Their results show that long-term exposure can increase bee deaths at levels 101-fold lower than detected in prior shorter-term studies and increase the number of abnormal bee behaviors such as loss of coordination and hyperactivity.

Among pesticides, the neonicotinoids have received major attention. Used globally since the 1990s, they now face regulatory challenges due to their demonstrated harmful effects on bees. Pest insects are also developing resistance against them. As a result, new generations of insecticides are entering the market. Flupyradifurone (the active ingredient in Sivanto®) is a next-generation systemic neurotoxic insecticide, first registered in 2014, that can be used to control a variety of pests on multiple crops. Flupyradifurone can be used on flowering crops when bees are actively foraging on them. However, the studies assessing its safety for pollinators focused on potential short-term and lethal impacts. The environmental ramifications of many of the world’s most commonly employed pesticides may thus be severely underestimated. In fact, bees can be exposed to pesticides in the pollen and honey bees stored inside their colony over extended time periods, up to months.

Even if bees do not immediately die, exposure to such pesticides can cause behavioural alterations that reduce lifetime and health of individuals and the whole colony.

This research is a model for future studies because it coordinates research on pesticides and risk assessments across multiple countries and continents, especially significant given that pesticides are subject to different approval processes in different countries. The authors propose innovative assessments of pesticide toxicity in bees and other insects. They conclude that long-term and sublethal effects should be routinely investigated by research and risk assessments to safeguard bees and our environment.

These findings raise concerns about the chronic impact of pesticides on pollinators at a global scale and support a novel methodology for a refined risk assessment.

The authors proposal of a new method for risk assessments to reduce underestimation of long-term pesticide risks represents an important step towards a greater protection for insect pollinators.

Tosi, S., Nieh, J.C., Brandt, A. et al. Long-term field-realistic exposure to a next-generation pesticide, flupyradifurone, impairs honey bee behaviour and survival. Commun Biol 4, 805 (2021).

RAI, La Repubblica, Il fatto quotidiano, La Stampa, Le Scienze, Il fatto alimentare

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