Biological control of pests is the method of controlling pests, whether of plants, animals or man, by exposing them to their natural enemies or unfavourable conditions. It includes such techniques as the introduction of exotic predators or diseases of the pest organism, manipulation of the pest's environment, the breeding of crop plants resistant to disease, releasing sterile males of a pest to interfere with reproduction, using sex attractants to trap and kill males before mating can ensue, and manipulating genes in order to render males sterile. However, it is underutilized in many of the developing countries which could best benefit from it.
In central and south China, the snail hosts of schistosomiasis were effectively controlled by cutting away the sloping sides of ponds and canals to create vertical walls which were a less hospitable environment than a gentle slope at the junction of land and water which the snails prefer for mating. This method of vector control was possible and successful because of the labour-intensive Chinese rural economy, and thorough understanding of the habits of the local snails; such a combination does not often occur.
Unlike the ensured control obtained from the use of chemicals, biocontrol is variable. Developmental research on such control methods is long and, upon application, may take years to be effective. In addition, an introduced 'natural enemy' may itself become an unwanted pest over time.
Biocontrol is economically feasible in that it establishes a once-for-all self-regulatory system in which natural enemies keep the pest in check below a damaging level without any further effort or expense. It utilizes no chemicals which threaten, pollute or damage the environment or serve to introduce chemical-resistant strains. Finally, biocontrol utilizes none of the fossil fuels that are required in the production of chemical products.
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