Sterile insect release

Crop Protection. Cotton can be affected by insects (30), weeds, diseases (31), nematodes, and mycotoxins. About 90% of the U.S. cotton uses Integrated Pest Management (IPM) practices. This approach optimizes the total pest management system by utilizing all available tools, including rotation, crop residue destruction, maximum crop competitiveness, earliness, pest scouting, action thresholds, releases of beneficial insects, sterile insect releases, and selective crop protection chemistry. 

Genetic Control. Some Insect pests have been successfully controlled by releasing sterile Insect males in sufficient quantity so that the pest population cannot reproduce. This has proven particularly effective in the control of the screwworm fly, a major pest of cattle (33). Genetic engineers may be able to provide other genetic techniques that will enhance the control of crop pests (34). 

Disrupt colonisers Population regulatio Mating confusion, trap cropping, sterile male releases, and low voltage soft electrons for insects, fences, trapping, netting for birds and mammals, sealant, reflective tape and startling sound for birds and rodents n Occasional Occasional... 

The requirement for a high action specificity of a chemo8terilant is fully justified when the compound is to be used for sterilizing insects that are to be released. However, a sterilant that is to be applied in the field where it may contact not only adults but also all the immature stages of the insect does not have to be specific in fact, its effectiveness would drastically increase if it would sterilize the adults and kill or otherwise incapacitate the immature. To turn around this argument, one can also say that a sterilizing activity in adults is a most desirable property of any ovicide or larvicide that is used in situations where all stages of the pest are present simultaneously or in short succession. 

Chemosterilants might be used in two basic ways—as a substitute for radiation to sterilize insects that had been reared for release in large numbers or as a means of inducing sterility in a large proportion of the natural population, thus avoiding the necessity for rearing and... 

Several methods have been proposed for the practical application of insect sterilants, such as contact, oral ingestion and sterile male release method. This latter method involves capture of the males, their chemosterilisation and subsequent release which means considerable excess of work compared to the usual application of pesticides. Nevertheless it seems particularly advantageous because under appropriate conditions it permits almost complete control of undesirable insect populations in several generations. 

IPM programs have been most effective for cotton, sorghum, peanuts, and fruit orchards, but less effective for corn and soybeans. Some of the biological controls include release of sterilized insect pests, use of insect pheromones to disrupt mating, release of natural predator pests, and use of natural insecticides. 

There have been two main lines of development in the control of insects by irradiation firstly, the disinfestation of stored products at doses sufficient to prevent reproduction of the insect, and secondly, eradication of insects in the field by the technique of sterile male release. Both lines of approach have achieved success, a plant for the disinfestation of grain being under construction in Turkey at this time, whereas in the United States, success in the elimination of the screw-worm fly has been achieved, and recently it has been announced that control of fruit flies can be effected in this way. 

Release of sterilized males. In this method very large numbers of, say, the male of the pest insect species are bred and are then sterilized by exposure to X- or 7-radiation. They are then introduced into the problem area in such numbers that there are far more of them than there are natural, fertile males, so that mating is much more likely to involve a sterile insect. As a result no offspring will be produced. Thus in time the population will decline and insects will no longer be a pest. 

Table 10. Theoretical Effects of Release of Sterile Male Insects on a Natural Insect Population ...

Mass releases of sterile male insects have produced dramatic reductions in the populations of the Mediteranean fmit dy Ceratitis capitata in California beginning in 1981 when 40 million sterile dies were released weekly and in the codling moth Cjdiapomonella in isolated apple orchards in the Pacific Northwest. 

Genetic Control. Manipulation of the mechanisms of inheritance of the insect pest populations has occurred most successfully through the mass release of sterilized males, but a variety of other techniques have been studied, including the environmental use of chemosterilants and the mass introduction of deleterious mutations, eg, conditional lethals and chromosomal translocations (58 ndash 60) (see GENETIC ENGINEERING). 

Additional control measures include use of Bacillus thurlngiensis formulations and the release of parasites and predators. There is a continuing program to find new species that can be imported and released. A virus has also been registered for use against the insect. Work on release of sterile males is in an early stage. 

More information must be available on the toxicity of the promising compounds before the full range of possible methods of application for the control of various species can be determined. Chemosterilants can certainly be used in the control of some species to sterilize reared insects for release among natural populations. No doubt they will also prove acceptable for use with various baits and attractants, which would bring them into contact only with the species... 

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