According to research by scientists from the University of Stirling, changing the diet of pests can slow down the development of resistance to biopesticidal fungi. This method implies that these biopesticides will maintain their effectiveness over a longer period, which is likely to increase food security, reduce environmental harm, and enhance biodiversity in agriculture.
Scientific experiments have shown that the cotton bollworm (Helicoverpa armigera), a moth species causing significant damage to agriculture, exhibits diverse genetic survival traits after exposure to biopesticidal fungi on different crops. Genotypes of the cotton bollworm that demonstrated high levels of protection when feeding on certain plants usually became more vulnerable when feeding on a different species.
The research indicates that the impact of biopesticidal fungi can contribute to the development of resistance, similar to synthetic pesticides. This is based on previous findings highlighting the importance of new approaches to risk management in terms of resistance, especially in the context of biopesticides.
Researchers point out that changes in the pest's diet have a more significant influence on the resistance development process than changing the type of pesticide used. In simpler terms, the diversity of cultivated crops can affect the speed at which pests adapt to biopesticides.
Scientists from the Faculty of Natural Sciences at the University of Stirling (Sweden) together with researchers from the University of São Paulo (Brazil) and the University of Gothenburg (Sweden) conducted experiments involving the cultivation of thousands of cotton bollworm larvae from different family lines in laboratory conditions and tested their survival rates after exposure to two different fungal pathogens while feeding on tomatoes, corn, or soybeans.
The experiments were conducted under controlled laboratory conditions at the University of Stirling using fungi from Brazil with the support of international partners. The research included selection and advanced statistical modeling to identify genetic patterns.
During the study, the survival of 3811 H. armigera larvae was quantitatively evaluated. The action of two types of fungal pathogens (Beauveria bassiana and Metarhizium anisopliae) resulted in significantly higher larval mortality compared to non-infected larvae, regardless of the diet. However, there was variation in baseline mortality rates for larvae consuming three different types of plants: larvae consuming soybeans showed better survivability, while those consuming tomatoes or corn had a higher risk of death. Thus, the ability of fungi to destroy larvae depended on the combination of the fungal strain and the larvae's diet in terms of agricultural crops.
The experiment was based on a study published in 2023, which indicated that agricultural pests already carry genes that enhance their resistance to infections, potentially leading to resistance against biopesticides.
Dr. Rosie Mangan, a research fellow at the University of Stirling, stated: "This is an important discovery as we have demonstrated the potential for significant changes in survival rates after exposure to biopesticides, and that farmers can slow down this process by using more diverse farming methods. Understanding the impact of diet on pests' resistance to fungal biopesticides will help develop sound and biologically based crop protection strategies, maintaining the effectiveness of biopesticides in the long term. These findings are particularly relevant for agricultural policies in the UK, EU, and other regions that use biopesticides."
The article was published in the journal PLOS Pathogens. DOI: 10.1371/journal.ppat.1013150
Dr. Mangan, along with Professor Matthew Tinsley and Esther Ferrari from the Faculty of Natural Sciences at the University of Stirling, Dr. Luke Bussier from the University of Gothenburg, and Dr. Ricardo Polanczyk from the University of São Paulo, collaborated on the research. This study was part of an extensive international program aimed at enhancing crop protection resilience.
