Improper use of fungicides can trigger outbreaks of "Helicoverpa armigera"

Recent study warns that excessive use of copper-based fungicides in agriculture can cause adverse effects on ecology and pest management, including increased caterpillar resistance and adaptation Helicoverpa armigera, one of the world's major agricultural pests.

Research conducted by Wenhui Lu and collaborators at Henan Agricultural University, China, highlights how prolonged exposure to copper affects the development, metabolism and behavior of this pest, as well as negatively impacting its natural enemies.

Metabolism and tolerance

The study simulated field conditions with different concentrations of copper in the diet of H. armigera.

Although the general survival and development rates of the larvae were not significantly altered, a significant increase in metabolic activity and in the expression of genes related to detoxification was observed.

Enzymes such as GST, CarE and CYP450 were amplified, allowing the pest to consume more food and better resist insecticides such as azadirachtin and chlorantraniliprole.

In addition to increasing tolerance of H. armigera pesticides, copper-based fungicides also harm wasp parasitism.

The parasitism rate fell from 61,7% in untreated larvae to 40% in those exposed to copper, indicating that the application of fungicides can destabilize the ecological balance.

Recommendations for fungicides

The researchers recommend careful evaluation of the impact of copper-based fungicides, especially in agricultural settings that rely on integrated pest management practices.

They warn of the need to synchronize the application of fungicides and insecticides, ensuring that copper residues are degraded before using insecticides, to avoid strengthening the pests.

More information can be found at:

• doi.org/10.1016/j.pestbp.2025.106297

• Helicoverpa armigera