What is the main characteristic of systemic pesticides?

The main characteristic of systemic pesticides is that they are absorbed by the plant or organism and then distributed throughout its system. This allows these pesticides to act from within the plant, targeting pests that feed on any part of the plant, including leaves, stems, and roots. This internal distribution makes systemic pesticides particularly effective against a variety of pests that might be harder to control with surface-insecticides, which only act on the exterior and may miss insects that are feeding inside or on hidden surfaces.

Their absorption into the plant ensures that the active ingredients can reach and disrupt the biological processes of target pests regardless of their feeding location. For example, when a systemic pesticide is applied to the soil, plant roots take it up, and it moves through the vascular system to various parts of the plant, making it lethal to sap-sucking insects like aphids and whiteflies that feed on the plant's sap.

In contrast, other options describe characteristics that do not apply to systemic pesticides. They do not act solely on the surface, are not applied as gases, and their effectiveness is not solely dependent on warm conditions; they can be effective across a range of environmental conditions, depending on the chemical formulation.