Researchers from the University of Stirling – together with colleagues from the University of Gothenburg and Brazil – have investigated how pests (specifically cotton bollworms) respond to biological pesticides, that is, fungus-based agents used as an environmentally friendly alternative to chemical pesticides.
They discovered that the larvae’s diet influences which insects show resistance to these biological pesticides. While certain genes may enhance survival on one crop, the same genes can reduce survival when the insect feeds on another. This variation in fitness across host plants is likely to delay the evolution of resistance.
“This is an important insight because we show that resistance to biopesticides can evolve quickly, but also that the process can be slowed by using a more diverse cropping system,” says Dr Rosie Mangan, researcher at the University of Stirling.
Under controlled laboratory conditions, thousands of larvae from different family lines were raised and exposed to two different fungal pathogens while being fed either tomato, maize or soybean. The study combined breeding experiments with advanced statistical modelling to understand the genetic patterns behind larval survival.
“For pesticides to remain effective, we need a holistic approach that includes biodiversity, crop rotation and an understanding of pest biology. Our results contribute to the development of more sustainable crop protection strategies,” says Luc Bussière, senior lecturer at the Department of Biological and Environmental Sciences.
This is important because resistance causes pesticides to stop working. By cultivating a wider variety of crops, pest control can become more sustainable and reduce the need for chemicals – which in turn benefits the environment, biodiversity, and food security.
The findings are particularly relevant for regions increasing their use of biopesticides, such as Sweden, the UK and the EU.
“By considering how the pests’ diet affects their resistance to pesticides, future agriculture can become both more effective and more environmentally friendly,” Luc Bussière concludes.