What is the key difference between systemic and contact pesticides?

• A. Systemic pesticides are absorbed and move within the plant to control pests.
• B. Contact pesticides must be applied to the soil to be effective.
• C. Systemic pesticides only act on insects that touch the foliage.
• D. Contact pesticides move inside the plant to reach pests.

Answer: (A)

Systemic pesticides work by being absorbed by the plant and then moving through its tissues so the chemical is present inside the plant to protect against pests as they feed. This internal movement means the pest doesn’t have to directly contact the spray on the surface—the pest ingests the pesticide when it chews or sucks on treated plant parts, or benefits from protection as the plant translocates the chemical to new growth.

That’s why the statement that best describes the difference is that systemic pesticides are absorbed and move within the plant to control pests. The other ideas miss this core point: some imply soil is always required for effectiveness, others suggest systemic pesticides act only on pests that touch foliage, and others claim that contact pesticides move inside the plant.