Authors: Thomas Perrot, Niklas Möhring
Title Photo by Vincent Bretagnolle
Most people assume that more pesticides mean fewer pests and bigger harvests. However, for some situations this relation becomes more complicated. A new study from French oilseed rape fields reveals that overusing insecticides cannot only be negative for the environment – but can also shrink crop yields.
The fight against insect pests in agriculture has long depended on synthetic insecticides. While effective in the short term, these chemicals also raise serious concerns about their impacts on the environment, biodiversity, and human health (1, 2). Farmers often face a dilemma: reducing insecticide use seems risky because it could lower crop yields (3). But the relationship between insecticides and yield is far from straightforward (4–6).
One often-overlooked factor is natural pest control—the work of beneficial organisms such as spiders, ladybugs, and beetles. These “allies in the field” can keep pests in check, sometimes just as effectively as insecticides (7, 8). However, when insecticides are applied, they often do not only target harmful insects but also beneficial ones. This weakens this natural defense system (9, 10). The result can even be the opposite of what is intended: a secondary outbreak of pests and greater crop damage (11, 12).
In our recent study (Perrot et al., 2025 (13)), we examined this complex relationship in 383 oilseed rape fields in western France, surveyed between 2011 and 2020. Oilseed rape is one of Europe’s most insecticide-intensive crops, making it an ideal test case. We used statistical models to untangle the direct effects of insecticides on pests and their potential indirect effects by disrupting natural pest control. We also considered the role of surrounding landscapes, which influence how strong natural pest control can be.
Our results were striking. Yields actually declined when insecticide use exceeded 36 grams of active substance per hectare (Figure 1A). Heavy insecticide use reduced natural pest control organisms by 29 percent and weeds by 12 percent (Figure 1B). When natural pest control was intact, it proved powerful, cutting pest insects by up to 72 percent and weeds by 35 percent (Figure 1B). Pests and weeds, in turn, reduced yields by as much as 25 percent and 21 percent, respectively (Figure 1B).
Figure 1. (A) Relationship between insecticide and yield. (B) Relationship between insecticide use, natural pest control (seed and insect), pest (insect pest and weed) and oilseed rape yield. Insecticide use is in g of active ingredient per hectare. In B., positive relations are in blue, negative one in red. Significant relations (p-value < 0.05) are represented by solid lines, marginal ones (p-value < 0.1) are dotted and non-significant are not represented.
The takeaway? Too much insecticides can backfire. Instead of protecting harvests, insecticide use over a certain threshold may weaken natural allies, increase pest pressure, and ultimately reduce yields. Our results suggest that low doses of insecticides provide benefits, but they cannot be combined with natural pest control without undermining it. Reducing high insecticide use may therefore offer a double benefit: more sustainable farming and better long-term productivity.
Our results are limited to the case of oilseed rape in France – further research in this field is needed to entangle the relation between pesticides and productivity, accounting for natural pest control. Looking ahead, calculating the true economic cost of overusing insecticides—by factoring in both the expense of spraying and potential damages on natural pest control—could provide a strong incentive for farmers to reduce insecticide use. Striking a balance between current pest control practices and nature’s own pest control systems can be a promising path toward resilient, productive, and environmentally friendly agriculture.
Thomas Perrot is at Fondation pour la Recherche sur la Biodiversite (France), Niklas Möhring is at the University of Bonn.
Further co-authors of Perrot et al. (2025), were Adrien Rusch at INRAE, Bordeaux Sciences Agro, France and Sabrina Gaba and Vincent Bretagnolle at Centre d’Etudes Biologiques de Chizé, France.
Perrot, T., Möhring, N., Rusch, A., Gaba, S., & Bretagnolle, V. (2025). Crop yield loss under high insecticide regime driven by reduction in natural pest control. Proceedings B, 292(2051), 20250138. https://doi.org/10.1098/rspb.2025.0138
References
1. D. Díaz, S., Demissew, S., Carabias, J., Joly, C., Lonsdale, M., Ash, N., Larigauderie, A., Adhikari, J. R., Arico, S., Báldi, A., Bartuska, A., Baste I. A., Bilgin, A., Brondizio, E., Chan, K. MA., Figueroa, V. E., Duraiappah, A., Fischer, M., Hill, R., Koe, The IPBES Conceptual Framework — connecting nature and people. Science Direct 14, 1–16 (2015).
2. S. Mostafalou, M. Abdollahi, Pesticides: an update of human exposure and toxicity. Arch Toxicol 91, 549–599 (2017).
3. J. Popp, K. Peto, J. Nagy, Pesticide productivity and food security. A review. Agronomy for Sustainable Development 33, 243–255 (2013).
4. V. Gagic, et al., Combined effects of agrochemicals and ecosystem services on crop yield across Europe. Ecology Letters (2017). https://doi.org/10.1111/ele.12850.
5. S. Macfadyen, et al., Reducing Insecticide Use in Broad-Acre Grains Production: An Australian Study. PLoS ONE 9, e89119 (2014).
6. R. Bommarco, F. Miranda, H. Bylund, C. Björkman, Insecticides suppress natural enemies and increase pest damage in cabbage. Journal of Economic Entomology 104, 782–791 (2011).
7. G. X. Boldorini, et al., Predators control pests and increase yield across crop types and climates: a meta-analysis. Proc. R. Soc. B. 291, 20232522 (2024).
8. F. Ratto, et al., Biological control interventions reduce pest abundance and crop damage while maintaining natural enemies in sub-Saharan Africa: a meta-analysis. Proc. R. Soc. B. 289, 20221695 (2022).
9. M. R. Douglas, J. F. Tooker, Meta-analysis reveals that seed-applied neonicotinoids and pyrethroids have similar negative effects on abundance of arthropod natural enemies. PeerJ 2016 (2016).
10. M. Řezáč, V. Řezáčová, P. Heneberg, Contact application of neonicotinoids suppresses the predation rate in different densities of prey and induces paralysis of common farmland spiders. Scientific Reports 9, 1–9 (2019).
11. J. D. Dutcher, “A Review of Resurgence and Replacement Causing Pest Outbreaks in IPM” in General Concepts in Integrated Pest and Disease Management, A. Ciancio, K. G. Mukerji, Eds. (Springer Netherlands, 2007), pp. 27–43.
12. A. Janssen, P. C. J. Van Rijn, Pesticides do not significantly reduce arthropod pest densities in the presence of natural enemies. Ecology Letters 24, 2010–2024 (2021).
13. Perrot, T., Möhring, N., Rusch, A., Gaba, S., & Bretagnolle, V. (2025). Crop yield loss under high insecticide regime driven by reduction in natural pest control. Proceedings B, 292(2051), 20250138.