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A field experiment shows that granivorous birds tend to avoid crops sowed with seeds treated with the neonicotinoid insecticide imidacloprid
Seeds treated with neonicotinoid pesticides such as imidacloprid and the cotyledons (the first leaf of the plant embryo) that grow from them may pose a toxicological risk to birds that feed on them. However, birds exposed to this type of pesticides could change their foraging behavior due to aversion and anorexia caused by this type of plant protection product, which would have consequences in the environmental risk assessment of these insecticides.
To assess whether avoidance behavior towards pesticides limits exposure and, consequently, risk to birds, researchers from the Instituto Nacional de Tecnología Agropecuaria (INTA) and the Research Group in Wildlife Toxicology of the Instituto de Investigación en Recursos Cinegéticos (IREC – CSIC, UCLM, JCCM) have developed a field experiment for which three soybean fields were sown at the Paraná Agricultural Experimental Station of INTA.
Globally, soybean cultivation represented 13% of grain production from 2020-2021, reaching 363 million tons produced on 129 million hectares, with the United States, Brazil and Argentina being the main producers and exporters in the world. .
Half of the surface of each field was sown with seeds treated with 42 g/100 kg seed of insecticide imidacloprid and the other half with seeds without imidacloprid. Unburied seeds were surveyed at 12 h and 48 h post-sowing and damaged seedlings was surveyed at 12 days post-sowing. Abundance and richness of birds was surveyed at the field level before, during, and after sowing, and 12 days post-sowing.
The results show that seed density was higher in the headlands of the imidacloprid-treated plots than in the control plots, but did not differ between 12 and 48 h. The damage on cotyledons of seedlings was XNUMX% higher in control plots than in imidacloprid-treated plots. The abundance and richness per hectare of birds that eat seeds and cotyledons were lower after sowing, indicating a deterrent effect of sowing imidacloprid-treated seeds on birds.
Neonicotinoids are neuroactive insecticides designed from nicotine. A previous experimental work with the dove, a South American dove, analyzed the effects of repellency, anorexia and aversion caused by neonicotinoid substances in birds to be considered in the evaluation of ecotoxicological risks.
Although the variation in seed density over time does not allow solid conclusions to be drawn about the avoidance of seeds treated by birds (owing to environmental factors such as heavy rains during sowing days), the seedling results suggest an aversive effect of imidacloprid-treated soybeans on birds.
The scientific publication of this research is available at:
- Addy-Orduna, L., Mateo, R. 2023. Field availability and avoidance of imidacloprid-treated soybean seeds and cotyledons by birds. Environmental Toxicology and Chemistry
