Production methods

Two types of fermentation methods are used for the production of bacillus thruringiensis and B sphaericus spores, whereas B popilliae or B lentimorbus spores are produced exclusively in living insects.

In the first type of fermentation spores of concerned microbe are produced on a semisolid medium composed of wheat bran, expanded perlite, soybean meal, glucose and inorganic salts. The bran is harvested after 36-48 hours and formulated to produce active against insects.

In the second type of fermentation what is popularly known as submerged fermentation B thruringiensis is carried out in a liquid medium using standard protein andcarbohydrate source. After sporulation of the bacteria, the spent liquor is passed through a fine screen, the active ingredients are centrifuged.

After sporulation of the bacteria, the spent liquor is passed through a fine screen, the active ingredients are centrifuged from the medium, mixed with stabilizing agents, and then packaged as either a powder or liquid.

For in vivo production of B popilliae and B lentimorbus, third instar Japanese beetle (popillia japonica) larvae are infected with spores and incubated in soil seeded with rye to feed the larvae. The infected larvae are harvested 16-21 days after infection. The infected larvae are pulverized, stabilizing agents are added, and the slurry is dried and packaged as dry powder.

Safety and specificity

B thruringiensis, B popilliae, B lentimorbus and B sphaericus have been subject to many safety tests, with no harmful effects for animals or human beings.

In 1980-81 because of large-scale application of B thruringiensis based biopesticideslot of damage was reported to silkworm pupae in the State of Karnataka. In fact, this deadly impact on the silkworm pupae and industry gave temporary setback to the application of BT based biopesticides.

Efficacy

Entomopathogens have been used to control mites, beetles and caterpillar pests of agricultural crops, forests and stored products with varying degree of success.

Microbial insecticides, like chemical insecticides, are usually sprayed or dusted on crops. Entomopathogens may also be successfully introduced and established in an ecosystem by other application methods such as insect traps and so on to provide long-term control of pests.

Virus or fungus might be induced in an insect population before crop-damaging proliferation takes place. It may be also possible to manipulate the environment to create conditions in which naturally occurring pathogens exert their greatest effect.

Many of these bio-control methods of pests may provide levels of control equal to or sometimes better thanthose currently obtained with chemical pesticides. But unfortunately chemical pesticide lobby in this country is so strong that these established multinational or indigenous companies are not allowing new products and safe eco-friendly methods to be introduced in the country by putting pressure on Commissioner of Pesticides. With a result the registration of such products become pretty difficult to new enterprises. Government also has put the biopesticides in the category of chemical pesticides.

However, once the registration of the product and NOCs from state and Union government are obtained manufacture of biopesticides is indeed one of the most lucrative venture to flat in the field of agricultural biotechnology. Biotechnology Resource Centre, Mumbai has developed indigenous and relatively cheap know-how to produce these products.

New entrepreneurs can certainly take this venture as the total investments of Rs 30-35 lakh or so one can achieve a turnover of Rs 2-5 crore within just couple ofyears.

Development of the use of entomoppathogenes or their by-products for microbial control agents is more or less under exploited in our country considering the market size. Safe, effective entomopathogens formulated as governmental agencies and industry are developing microbial control agents, and growers slowly in our country are effectively using the commercial products. Needless to say that the newer agents have not been brought to their fullest potential.

By adopting a systems approach to "integrated pest management" using entomopathogens and other non-chemical factors for specific pests, developing country like ours has a coveted opportunity to bypass traditional approach to insect control.

All types of microorganisms are represented among the potential microbial control agents. As an example, nearly 100 species of bacteria and over 700 viruses have been isolated from arthropods and more are being discovered each year.

Biopesticides based on bacillus thruringiensis (Bt) and bacillussphaericus (Bs) were approved for large-scale use in the country from the later part of 1993 and three companies started marketing imported biopesticides based on Bt and Bs.

Department of Biotechnology (DBT) sponsored several R&D projects since March 1989 at various agricultural universities to evolve methods for the selection and pilot scale production of organisms like viruses and bacteria, which are pathogenic to insect pests.

Through these production techniques for multiplication and formulation of nuclear polyhedrosis virus (NPV) to control cotton bollworms and tobacco caterpillars were standardized. Many more fungal and bacterial formulations are also being developed for control of root rot and white flies the most dangerous of pests.

Using these formulations controlled field level demonstrations in farms have been conducted and so far nearly 25,000 hectares have been covered in the fields of cotton, sugarcane, tobacco, sunflower, cabbage and cauliflower.

The results obtained are quiteencouraging. Steps are now being taken by the government to set up production units for mass multiplication and formulation of biocontrol agents with a view to commercialization of these biopesticides. While doing so due care is taken about generating the data on mandatory environmental safety and efficacy.

In the last five years in our country at least nine private companies have launched Bt based biopesticides plants.

It is visualized by and large that the wide application of these biocontrol agents would lead to considerable saving in both quantity and cost of chemical pesticides. These efforts would also lead to greater sustainable and eco-friendly agriculture and horticulture by minimizing the pollution of chemicals and improve not only health of our crops but also of human beings.