What is a disadvantage of systemic insecticides?

What is a disadvantage of systemic insecticides?

• A. They are always cheap.
• B. They provide perfect control of all pests.
• C. They have poor control of large chewing insects.
• D. They work instantly for all pests.

Answer: (C)

Systemic insecticides are taken up by the plant and move through its tissues, so insects that feed on those tissues ingest the chemical. This makes them especially effective against sap-sucking pests and offers long-lasting protection. But they tend to perform poorly against large chewing insects like caterpillars and some beetles. These pests chew through plant parts and may not consistently ingest enough of the systemic toxin quickly, so control can be incomplete or slow. They also don’t provide instant knockdown, since it takes time for the plant to absorb, translocate, and for the insect to ingest the toxin. So, the main drawback is poor control of large chewing insects.

Systemic insecticides are taken up by the plant and move through its tissues, so insects that feed on those tissues ingest the chemical. This makes them especially effective against sap-sucking pests and offers long-lasting protection. But they tend to perform poorly against large chewing insects like caterpillars and some beetles. These pests chew through plant parts and may not consistently ingest enough of the systemic toxin quickly, so control can be incomplete or slow. They also don’t provide instant knockdown, since it takes time for the plant to absorb, translocate, and for the insect to ingest the toxin. So, the main drawback is poor control of large chewing insects.