Which practice can help maintain pest population levels that are manageable?

Establishing biological control agents is a practice that effectively helps maintain pest population levels at manageable levels. Biological control involves the use of natural predators, parasites, or pathogens to keep pest populations in check. This approach promotes a more balanced ecosystem and often leads to a sustainable solution for pest management. By introducing or enhancing these natural enemies, crop specialists can reduce reliance on chemical pesticides, decrease the likelihood of pest resistance, and promote biodiversity within the environment.

In contrast, the other options fail to provide effective long-term pest management strategies. Constant application of the same pesticide can lead to pesticide resistance, making pests more difficult to control over time. Allowing unrestricted pest growth can result in severe crop damage and reduced yields, while using exclusive reliance on broad-spectrum pesticides may harm beneficial organisms in the environment, leading to disruption of the ecosystem. Therefore, establishing biological control is preferred for maintaining pest populations at manageable levels and contributing to ecological health.