Which would increase the likelihood of pesticide resistance?

Continual use of pesticides from the same chemical class significantly increases the likelihood of pesticide resistance. When a specific pesticide or chemical class is used repeatedly over time, it creates selective pressure on pest populations. This means that any pests that have or develop genetic mutations granting them resistance to that chemical are more likely to survive and reproduce. As a result, the population of pests gradually becomes composed of individuals that are less susceptible to that pesticide, leading to a situation where the pesticide becomes ineffective.

In contrast, an insect that has one generation per year may not increase resistance as quickly, as its lifecycle limits the opportunities for resistance to develop in a short time frame. Applying a pesticide with little or no residual effect reduces the overall exposure of the pest population to the chemical, thus limiting the chances for resistant individuals to thrive. Rotating pesticide classes each season helps to manage resistance by reducing the selection pressure on any one chemical, allowing for a more sustainable pest management strategy.