What is a key limitation of systemic insecticides in terms of insect groups?

What is a key limitation of systemic insecticides in terms of insect groups?

• A. Poor control of large chewing insects.
• B. They work only on termites.
• C. They have no effect on sucking insects.
• D. They are ineffective indoors.

Answer: (A)

Systemic insecticides travel inside the plant after uptake, so pests must feed on the plant tissues to become exposed. Because of this, they work best against sap-sucking pests that ingest plant fluids, such as aphids or whiteflies. Large chewing insects, like caterpillars or beetles, chew leaf tissue rather than feed on sap, so they often encounter lower concentrations of the insecticide and are not reliably controlled. That’s why the key limitation is poor control of large chewing insects. For context, other statements aren’t as accurate: these products aren’t limited to termites and can affect a range of sucking pests, not none of them; they’re not inherently ineffective indoors—systemics can be used in some indoor situations with the right product and label; and chewing pests aren’t the primary target, so the effectiveness against them tends to be the weak point.

Systemic insecticides travel inside the plant after uptake, so pests must feed on the plant tissues to become exposed. Because of this, they work best against sap-sucking pests that ingest plant fluids, such as aphids or whiteflies. Large chewing insects, like caterpillars or beetles, chew leaf tissue rather than feed on sap, so they often encounter lower concentrations of the insecticide and are not reliably controlled. That’s why the key limitation is poor control of large chewing insects.

For context, other statements aren’t as accurate: these products aren’t limited to termites and can affect a range of sucking pests, not none of them; they’re not inherently ineffective indoors—systemics can be used in some indoor situations with the right product and label; and chewing pests aren’t the primary target, so the effectiveness against them tends to be the weak point.