What are the characteristics of benzoylurea insecticides?
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Benzoylurea insecticides are also called insect growth regulators, and their insecticidal characteristics can be summarized in the following aspects.(1) Special insecticidal mechanism. After these insecticides enter the insect body, they inhibit the synthesis of the larval cuticle substance -- chitin -- so that the insect body cannot grow new skin, causing the insect to be unable to molt and die. It can thus be seen that benzoylurea insecticides only act on insects with molting habits. They are ineffective against adults that do not molt. However, they can cause indirect effects, such as sterility, reduced egg production, and lower egg hatching rates.
(2) Strong selectivity. They are effective only against molting insects and are safe for most natural enemy insects, aquatic organisms such as fish and shrimp, and bees.
(3) Low toxicity and low residue. Chitin is a cuticle substance unique to insects, and other animals do not have this substance. Therefore, toxicity to humans and animals is low, there is no chronic toxicity, they are easily decomposed in plant and animal bodies, residues in agricultural products are relatively low, and environmental pollution is small.
(4) Most varieties are not prone to resistance, and there is no cross-resistance with several other types of insecticides, but individual varieties quickly develop resistance after continuous use, such as chlorfluazuron against certain lepidopteran pests.
(5) The insecticidal action is slow. These insecticides act only during the insect molting process, and generally require at least 3 days to cause death. Therefore, they should be applied early during the young larval stage, and when pests occur severely, they should be used in combination with fast-acting insecticides.
(6) Because silkworms are molting insects, this type of insecticide is highly toxic to silkworms, so it should be used with caution in sericulture areas and surrounding areas.
The main varieties currently in use include: diflubenzuron, chlorbenzuron, chlorfluazuron, hexaflumuron, flufenoxuron, buprofezin, etc.