Why insecticides become less and less effective the more you use them

An insecticide often works very well when first used, but as the dosage keeps increasing and the scope of use keeps expanding, the product becomes less and less effective - this is actually because the pests have developed resistance. When one pest species develops resistance to one pesticide, it often is also resistant to other pesticides of the same type; this kind of cross-interaction is less likely to occur between products with different insecticidal mechanisms. The more times the same pesticide is used consecutively or the higher the treatment concentration, the faster resistance forms; conversely, it forms more slowly.

Therefore, first of all, the number of chemical control applications and the dosage should be reduced as much as possible.

Second, choose insecticides with different mechanisms of action to mix, rotate, and apply in a mosaic pattern.

Third, improve application techniques, such as treating the right pest, spraying at the right time, choosing efficient equipment, and spraying thoroughly, so as to maximize the killing effect.