How to Manage Pests
UC Pest Management Guidelines
Selectivity of Insecticides and Miticides
(Reviewed 5/13, updated 5/13)
In this Guideline:
Integrated pest management (IPM) makes use of all available control strategies, including cultural, host plant resistance, biological, and chemical controls to manage pests. Natural enemies are an extremely important component of integrated pest management of cotton insects and mites. Common natural enemies include lacewings, bigeyed bugs, damsel bugs, minute pirate bugs, lady beetles, thrips, and several parasitic wasps. Lacewings, lady beetles, and parasitic wasps help control cotton aphids. Spider mite populations can be controlled by predatory mites and thrips. Lepidopterous larvae can be controlled or suppressed by several species of natural enemies. Research has shown that 99% of beet armyworm, cabbage looper, and cotton bollworm eggs and early-instar larvae are consumed by predators in fields that have a natural population of predators and parasites. Some insects, such as thrips, can be predators (feeding on spider mite eggs) as well as plant feeders. Generally, the beneficial aspects of thrips outweigh the damage to seedling cotton.
Insecticides and miticides are also a useful component of IPM programs and are effective for reducing crop damage during periods of pest outbreaks. Using selective insecticides and miticides to kill the target pest without killing natural enemies helps maximize as well as integrate chemical and biological controls. Selectivity usually arises from the specific chemical aspects of the insecticide. Nonselective insecticides and miticides, however, can be made more selective by careful application rates, timings, gallonages, and coverage to minimize killing natural enemies.
For most major cotton insect and mite pests, a number of pesticides are available that differ in their toxicity to natural enemies. Botanical, microbial, oil, or soap insecticides are relatively nondisruptive to most natural enemies. In some cases, selective insecticides and miticides may not control pest populations as well as nonselective materials. However, use of selective materials for treatments, especially early in the season, allows natural enemies to survive, which in turn helps minimize outbreaks of pests such as mites and aphids later in the growing season.
Nonselective insecticides and miticides leave residues on the plant that may be toxic to predators and parasites for days to weeks following application, depending on the persistence of the product. Products that have a short residual effect on natural enemies are favored for IPM programs. Consider both the short-term and long-term effects of an application when selecting an insecticide treatment.
The table on SELECTIVITY AND PERSISTENCE OF KEY COTTON INSECTICIDES AND MITICIDES details information on the selectivity of a chemical, an important factor to consider when selecting a treatment. This includes the effect the material has on nontarget species, its persistence in the environment, and its toxicity to both the pest and to natural enemies.
UC IPM Pest Management Guidelines: