Which of the following is a sign of pesticide degradation?

The identification of failure of pest control methods as a sign of pesticide degradation is rooted in the fundamental understanding of how pesticides operate and their efficacy. When a pesticide degrades, it loses its active ingredients or effectiveness due to various factors such as environmental conditions, chemical breakdown, or microbial activity.

Consequently, if a pesticide is degrading, it will not provide the intended level of control over pests, leading to increased pest activity. This diminished effectiveness can manifest as a failure to suppress pest populations, making it a clear indication that the pesticide is no longer functioning as originally designed.

In contrast to the other choices, which suggest irrelevant or opposite outcomes of pesticide degradation, the failure of pest control methods directly correlates with the functional loss of the pesticide, making it a definitive sign of degradation.