Which of the following is a potential consequence of repeated use of the same pesticide?

The correct answer highlights a significant concern in pest management practices. Repeated use of the same pesticide can lead to the development of pesticide resistance in weeds. This occurs when weeds that have genetic mutations allowing them to survive the effects of a specific pesticide are selectively favored as the pesticide is used repeatedly. Over time, the population of these resistant weeds can increase, making it increasingly difficult to manage them with that particular pesticide. This phenomenon not only reduces the efficacy of the pesticide but also poses challenges that may require the use of more potent chemicals or alternative management strategies, which can have broader environmental and economic implications.

In contrast, the other choices do not represent likely outcomes of repeated pesticide use. For example, the expectation of increased effectiveness might apply initially, but as resistance builds, the effectiveness of that pesticide typically declines, not increases. The idea that pest population would decrease or that secondary pest problems would decrease does not hold true as well; often, when a primary pest is controlled with a given pesticide, secondary pests may proliferate due to the disruption of natural pest dynamics. Thus, the choice reinforcing the increase in pesticide resistance serves as a crucial insight into sustainable pest management practices.