What happens to pest populations that are repeatedly treated with pesticides of the same mode of action?

When pest populations are repeatedly treated with pesticides that have the same mode of action, they are likely to develop resistance. This occurs because maintaining consistent exposure to the same pesticide allows for the survival of individuals within the population that have a genetic mutation granting them tolerance to that specific chemical. Over time, these resistant individuals reproduce, leading to a situation where the entire population has higher resistance levels and may even become entirely resistant to that pesticide.

Developing resistance can dramatically reduce the efficacy of the pesticide, making it less effective in controlling pest populations. Consequently, pest management strategies often emphasize rotating different pesticides with varying modes of action to mitigate the development of resistance and maintain effective control over pest species.

The other potential outcomes listed do not accurately describe the common consequence of repeated pesticide treatments with the same mode of action.