This is too broad to be supported. The author never indicates that control of agricultural pests is, in general, most effectively accomplished without pesticides. Rather, the author points out that sometimes allowing natural predators to keep pests in control is most effective.

This doesn’t capture the author’s view that sometimes allowing predators to eat pests is the most effective way to keep those pests under control. In addition, the author never suggests that we need experiments to demonstrate the effectiveness of natural controls of pests. The fact the author discusses an experiment does not imply she thinks they’re necessary.

This best captures the author’s point, which is that sometimes agricultural pests are best controlled by allowing natural predators of the pests to rein free. She expresses this point at the beginning of P1 and supports it in the rest of the passage using the example of cyclamen mites, which are best kept in check by allowing Typhlodromus mites to control their population.

The author never suggests that Typhlodromus mites are necessary to control cyclamen mites. They are more effective than pesticides, but that doesn’t imply they’re necessary. Also, the author uses the cyclamen and Typhlodromus example to support a broader point — that sometimes agricultural pests are best controlled by allowing natural predators of the pests to rein free.

This is one fact mentioned as part of the explanation for Typhlodromus’s ability to keep cyclamen in check. But it’s too narrow to be the main point of the whole passage.