Which statement best describes systemic insecticides' behavior in plant or animal tissues?

Which statement best describes systemic insecticides' behavior in plant or animal tissues?

• A. They are absorbed and moved throughout tissues.
• B. They stay only on the surface.
• C. They repel pests without killing.
• D. They are ineffective against sucking insects.

Answer: (A)

Systemic insecticides work because they are taken up by the plant or animal and then move through its tissues. In plants, the chemical can be absorbed by roots or leaves and is transported through the vascular system. Some systemic products move with the water streams in the xylem, reaching new growth and roots as the plant transpires, while others move via the phloem, distributing to growing points and developing tissues. This internal movement means pests feeding anywhere on the plant—whether on leaves, stems, or roots—ingest the toxic dose. That’s why these products are effective even when the pests aren’t directly treated on the surface. It’s not about just staying on the surface or simply repelling pests; systemic pesticides are designed to reach and kill pests that feed inside plant tissues, including many sucking insects.

Systemic insecticides work because they are taken up by the plant or animal and then move through its tissues. In plants, the chemical can be absorbed by roots or leaves and is transported through the vascular system. Some systemic products move with the water streams in the xylem, reaching new growth and roots as the plant transpires, while others move via the phloem, distributing to growing points and developing tissues. This internal movement means pests feeding anywhere on the plant—whether on leaves, stems, or roots—ingest the toxic dose. That’s why these products are effective even when the pests aren’t directly treated on the surface. It’s not about just staying on the surface or simply repelling pests; systemic pesticides are designed to reach and kill pests that feed inside plant tissues, including many sucking insects.