Biopesticides

What are bio pesticides?
All the living organisms, which are cultivated in the laboratory on large scale and are used and exploited experimentally for the control of harmful organisms are, called biopesticides. The examples include insects, virus bacteria, fungi, protozoan and nematodes.

Commercial status
World open market management and use of synthetic agrochemical and their unjudicious use are responsible in giving new horizon in the plant pests and diseases control. Food grains, milk and milk products and meat are treated with the chemical pesticides the quantity of which have crossed the minimal quantity prescribed (permissible limits) by World Food Organization (WFO). In 1940, the agrochemical DDT was introduced and was killing 600 species of insect at that time very actively and hence was used intensively. The intensive and unjudicious use of DDT created resistance problem in insects toward DDT and now only few species of insect are being killed by these pesticides. In 1990 the use of biopesticides as compared to synthetic insecticides was only 0.5% and recent data indicate that it has increased tremendously with Bacillus thuringiensis (BT). The interesting aspect of this that where as the market for synthetic pesticides reached a plateau, the market for biopesticides is increasing at the rate of 10 to 25% annually.

Advantages
The government is emphatically encouraging the use of biopesticides. The manufacturers are being given subsidy, no-licensing fees, and financial assistance and also encouraged to export. These are the reasons, which form the basis of commercialization of biopesticides. Some of them are:
1. Research expenditure: As compared to research on insecticides, research on biopesticides is cheap and fast.
2. Product development rates: As compared to biopesticides the formulation of synthetic insecticides is very difficult.
3. Registration charges: Side effects (nontarget effects), such as pollution problem and human toxicity of various insecticides is also very high Governments are cautions in issuing registration of insecticides. The registration charges are also very high.
4. Selectivity: Biopesticides are selectively toxic to certain groups of fungi only. Hence there is no possibility of pollution of environment and soil and there is no danger of residue problem in food and other eatable materials and also in animal food.

Disadvantages
There are lots of limitations in popularizing the wide spread use of biopesticides. Some of them are listed here:
1. Reliability: Since there is no stability on the effect of biopesticides farmers always look towards them with doubts. Because most the agents of biopesticides are living; several factors like temperatures, moistures, pH, ultraviolet spectrum and soil factors adversely affect the mode of action and their effectively is affected.
2. Natural control of population: After the maxima has reached, then autolysis starts and the effectivity is low. Biopesticides agents face stiff competition with other microbes, which may start controlling the biopesticides agents. Soil and their factors also control the population of biopesticides agents through a process called as self control buffering effect on population increase.
3. Specificity: Because of certain selectivity in their controlling effect towards insect-pest and pathogens, the farmers do not give prominence to biopesticides. Another pertinent point is that biopesticides are slow in action as compared to synthetic pesticides.
4. Shelf life: Biopesticides have a very short shelf life as compared to insecticides. The distribution of bio-pesticides in the market is also very erratic

However, the problems created by synthetic pesticides kindled interest of scientists in biopesticides. Consequently predators like cryptolaemus, parasitoids like Trichogramma, insect pathogens like Bacillus thuringensis and NPV, were commercialized for pest management during the past decade. Several fungi and bacteria are screened for their bioactivity towards several pathogenic insect-pests and fungi and the success rate has been very high.

Ag.
Technologies
(Pest Mgmt.)o