How does resistance to pesticides develop?

Resistance to pesticides develops primarily through the repeated use of the same pesticides in a specific location, leading to the selection of resistant individual pests. When a pesticide is applied multiple times, it targets a population of pests, and those individuals that happen to have genetic traits that confer resistance are more likely to survive and reproduce. Over time, these resistant pests become more prevalent in the population, resulting in reduced effectiveness of the pesticide.

In contrast, rotating different pesticides can help manage resistance because it exposes pests to different chemical modes of action, which can help reduce the selection pressure for resistance. Similarly, using higher concentrations may temporarily increase efficacy but does not address the root causes of resistance and can lead to greater selection for resistant individuals. Integrating cultural practices, such as crop rotation, maintaining healthy soil, and promoting biological control, also helps manage pest populations in a way that reduces reliance on chemical controls and lowers the potential for resistance development. Thus, reliance solely on repeating the same pesticide is the main factor in the development of resistance.