The complex effects that pesticides cause on bees

New research delves into the subtle cognitive, behavioural, and physiological effects that pesticides, alone or in combinations, have on bees

A new research, recently published on the scientific journal Science of the Total Environment, demonstrates the vast impact of sublethal and combined effects of pesticides on bees. The authors of the study, led by Simone Tosi (Department of Agricultural, Forest, and Food Sciences - University of Turin), also highlight how much we don’t know about these complex effects.

They conclude that risk assessment, the process evaluating the safety of a chemical and leading to the approval or rejection of its use, underestimates the risks posed by pesticides on bees and the environment.

In fact, risk assessment aims at protecting the health of bees and the environment, but focus on lethal effects only, not sublethal or combined ones.

The sublethal effects caused on pollinators are known for only the 29% of the most common pesticides. Furthermore, pesticides are typically found in the environment in mixtures, cocktails that can amplify synergistically their harm. This research demonstrates that we are unaware of the complex synergistic effects caused by the ~99% of the possible pesticide cocktails that bees could ingest.

This research thus proposes new methods and approaches for analysing and interpreting the lethal, sublethal, and combined effects of pesticides, including fungicides and herbicides, in bees. This integrative overview allows for new insights on pesticide ecotoxicity and bee health and will facilitate its implementation to future research and risk assessments, ones that better accounts for real-world complexities.

Risk assessors aim to keep people and the environment safe from the unacceptable consequences of pesticide use. The proposed harmonised and standardized approaches can help risk assessors more effectively meet their laudable mandate.

This research concludes emphasising the need for a more refined and holistic assessment of pesticide risks that do not only focus on lethality, towards a healthier environment for bees.

Original reference:
Tosi, S., Sfeir, C., Carnesecchi, E., VanEngelsdorp, D., Chauzat, M.-P., 2022. Lethal, sublethal, and combined effects of pesticides on bees: A meta-analysis and new risk assessment tools. Sci. Total Environ. 844, 156857. https://doi.org/10.1016/j.scitotenv.2022.156857

Press:
Le Scienze: "Gli effetti nascosti dei pesticidi utilizzati nei campi"