When a well-fed cricket is exposed to glyphosate, it invests more in maintaining its body and less in reproduction. When a poorly fed cricket is exposed to the same chemical, the opposite happens. A new study finds that the world’s most widely used weedkiller does not change what insects eat. It changes what their bodies do with food, and it does so in ways that depend on how hungry the insect already is.
A new study published in the journal Behavioral Ecology adds an important and genuinely unexpected piece to that picture. The researchers, from the University of the Pacific in California, found that glyphosate does not change what insects choose to eat. But it does change what the insect’s body does with the food once eaten, and the direction of that change depends entirely on how well-nourished the insect is to begin with.
The study used field crickets, specifically a wing-dimorphic species called Gryllus lineaticeps found across California, where glyphosate is the most commonly applied pesticide. These crickets are useful for this kind of research because they face a built-in trade-off: they can invest their resources into growing functioning flight muscles to disperse, or into producing eggs and reproducing. They cannot fully do both at once. That balance is sensitive to nutrition and to environmental stress, which makes the crickets a useful window into how agrochemicals interact with insect physiology.
The team gave crickets either plain water or a glyphosate solution to drink, at concentrations that match what insects encounter in agricultural environments. They then fed the crickets either a protein-rich diet, a carbohydrate-rich diet, or let them choose freely between the two.
The key finding was that glyphosate did not change the insects’ nutritional targets. Crickets exposed to glyphosate ate the same protein-to-carbohydrate ratio as unexposed crickets. The weedkiller was not making them hungrier, less hungry, or changing what they craved.
What glyphosate did change was allocation. When insects were well-nourished and could choose their diet freely, glyphosate shifted their investment toward body maintenance and away from reproduction. When insects were nutritionally stressed and restricted to an imbalanced diet, the opposite happened. Glyphosate pushed their investment toward reproduction at the expense of the body tissue needed for survival.
Glyphosate also eliminated something that normally gives well-fed insects an advantage. Under normal conditions, a protein-rich diet provides a significant boost to reproductive output. When glyphosate was present, that advantage disappeared entirely.
The implication is that the ecological impact of glyphosate on insect populations depends heavily on context. An insect living in a habitat with abundant, nutritionally balanced food may experience glyphosate as a drag on reproduction but maintain its body. An insect already struggling with poor-quality food, common in degraded or intensively farmed landscapes, may experience glyphosate as something that accelerates reproductive investment at the cost of longevity and physical condition. Neither outcome is straightforwardly good for the population.
This matters because insects in agricultural landscapes face both stressors simultaneously. Farming practices that reduce plant diversity narrow the nutritional options available to insects, and the same practices increase pesticide exposure. The new study suggests these two pressures do not add up in a simple way. They interact, and the interaction changes the nature of the effect depending on how well the insect is eating.
Sources
Stahlschmidt, Z.R. et al. “Macronutrient composition and glyphosate-based herbicide interact to influence resource allocation.” Behavioral Ecology, arag042 (2026). DOI: 10.1093/beheco/arag042 https://academic.oup.com/beheco/advance-article/doi/10.1093/beheco/arag042/8660708 Published: 22 April 2026
Stahlschmidt, Z.R. et al. “Multigenerational exposure to glyphosate has only modest effects on life-history traits, stress tolerance and microbiome in a field cricket.” Journal of Experimental Biology 228 (14): jeb250210 (2025). DOI: 10.1242/jeb.250210 https://journals.biologists.com/jeb/article/228/14/jeb250210/368248/Multigenerational-exposure-to-glyphosate-has-only
Treidel, L.A. et al. “Physiological demands and nutrient intake modulate a trade-off between dispersal and reproduction based on age and sex of field crickets.” Journal of Experimental Biology 224 (7): jeb237834 (2021). DOI: 10.1242/jeb.237834 https://journals.biologists.com/jeb/article/224/7/jeb237834/239063/Physiological-demands-and-nutrient-intake-modulate
Jane holds a BSc in Biology from the University of Regina and a Master of Science in Bioscience, Technology and Public Policy from the Univesity of Winnipeg. Her reporting interests include Life Sciences, Physical Sciences and the Cosmos.