Pesticide resistance is the ability of pests, such as insects, weeds, and fungi, to survive exposure to pesticides that were once effective in controlling them. This resistance develops over time as the pests evolve and adapt to the chemicals used to kill them. This can lead to a decrease in the effectiveness of pesticides and pose a significant challenge to agricultural productivity and food security. Researchers study pesticide resistance to understand the mechanisms behind it and develop strategies to manage and prevent it. This includes exploring alternative pest management techniques, developing new pesticides, and implementing resistance management practices.