Which class of insecticide is known for controlling sucking insects and is systemic in action?

The class of insecticide known for controlling sucking insects while being systemic in action is the neonicotinoid insecticide. Neonicotinoids work by mimicking nicotine, targeting the nervous system of insects, particularly those that feed on the sap of plants—like aphids and whiteflies. This systemic property allows the insecticide to be absorbed by the plant and transported throughout its tissues, making it effective against pests that feed on any part of the plant, including stems and leaves.

Other options, such as nematicides, are specifically designed to target nematodes, which are a different group of pests and do not primarily affect sucking insects. Pathogens refer to disease-causing agents like bacteria, fungi, and viruses, which are not classified as insecticides. Parasites are organisms that live on or in a host at the host's expense, and while they can control insect populations, they do this through biological means rather than chemical insecticides like neonicotinoids do.

Understanding that neonicotinoids are specifically designed to work systemically against sucking insects helps clarify their unique position in pest management strategies.