How does a systemic insecticide act on a pest?

A systemic insecticide is designed to be absorbed by a plant and then translocated throughout its tissues. When pests feed on the treated plant, they ingest the insecticide, which then disrupts key physiological processes within the pest, often targeting the nervous system or disrupting essential functions such as metabolism and reproduction.

The mechanism behind this type of insecticide is particularly effective because it allows for targeted action on the pests that consume parts of the plant—such as leaves, stems, or roots—while minimizing harm to beneficial insects or surrounding flora. This method ensures that the insecticide reaches the internal tissues of the plant, making it lethal to pests that are not simply on the surface but are actively feeding on the plant.

In contrast, the other methods—suffocating on contact, creating a barrier, or repelling pests—do not involve the internal action of the insecticide within the plant and do not specifically target the pest's ingestion of the plant material.