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Promoting use of microbial biopesticides
By
M. Saleem, S. Hussain, M. Arshad & Ziaulhasan
THE current use of pesticides in Pakistan is about 1,30,000
metric tons of which approximately 90 per cent is
applied on cotton, rice, fruits and vegetables. The wide
use of pesticides in agriculture has contaminated the
highly value-added commodities like rice, cotton,
vegetables and fruits.
 Due
to contamination and low quality, prices in
international markets have shrunken. The Indian and
Chinese are reaping bonanza from this situation due to
their relatively good quality products. The WTO regime
demands contamination-free commodities to compete in
local and international markets.
Recently biopesticides have received much attention as
an alternate to chemical pesticides. These comprise
living microorganisms (viruses, bacteria, fungi,
protozoa, or nematodes) or the metabolites produced by
them. These are applied as pesticides in the form of
sprays, dusts, liquid drenches, liquid concentrates,
wettable powders, or granules.
The investigation of microbes and their
bio-products/metabolites as pesticides dates back to the
discovery of Bacillus thuringiensis (BT) in 1902. In
1950, its toxic effect to insects was known to the
scientists. Since then, work on formulation of microbial
pesticides has witnessed many ups and downs. This was
the time when the use of chemical pesticides was gaining
popularity among the farming communities due to their
immediate and positive results. This factor visibly
influenced the commercial use of microbial biopesticides
in agriculture.
In the few last decades due to socio-economic,
environmental, and public concerns over the use of
anthropogenic pesticides, the importance of microbial
derived biopesticides has received currency among food
producers. Few examples of the microbes used for insect
pest control are listed in table 1.
Major advantages of microbial biopesticides are; (1) the
microbes used in preparation of these bio-pesticides are
non-toxic and non-pathogenic to wildlife, humans, and
other non-organisms; (2) these are highly specific to a
single group of insect pests and thus have no adverse
impact on other beneficial living organism; (3) these
could be employed where necessary with synthetic
pesticides; (4) their residues are harmless and these
could be used at the time of harvest and (5) applied
microbes may establish in pest population and could be
helpful in maintenance of their population below the
threshold level.
Their commercial scale production involves several but
relatively simple and environment-friendly steps.
Firstly, it involves the investigation of target pests
and its habitat and all those biotic and abiotic factors
which may influence its population. During this step, it
is important to identify microbial pathogens. Isolation
of microbes is carried out from its habitat and from the
body of diseased insects which undergoes the
purification of cultures under highly sophisticated
laboratory conditions. Efficient strains are screened
for their potentials to inhibit pest’s growth. Tests of
these isolated microbes are carried out to assess their
adverse impacts on other living organisms i.e., plants,
non-target insect pests and human beings. It is
investigated that the isolated strains must only be the
pathogens of target insect pests and it must not have
any harmful impact on other non-target organisms.
Pilot trials are conducted to determine their potential
to control pest population under field conditions.
Meanwhile different formulations, i.e., liquid, granular
and dust, etc., are also tested to find better and
comfortable ones. Recently, production of microbial
metabolites like cyanides is also used for pest control
in addition to the introduction of BT genes in plants.
Several kinds of metabolites have been characterized for
control of specific pests. Microbial biopesticides are
being used successfully on large scales in India, China,
the US, Australia and many other countries of the world
to break the momentum of synthetic pesticides’ use in
agriculture. But in Pakistan, no efforts have been made
to encourage their use in agriculture.
Commercial production of such kinds of biopesticides may
prove a good step toward organic agriculture and help in
the production of pesticide-contamination free
agri-products. To promote the use of microbial derived
biopesticides in agriculture following strategies could
be helpful. * Legitimate efforts should be made to
introduce this trend among relevant scientific domains
via assigning projects to relevant institutes to conduct
market-oriented research for the production of
microbially derived biopesticides. * Use of chemical
pesticides should be discouraged and regulatory measures
should be taken to divert private sector’s mindset
towards the commercial scale production of
biopesticides. ‘ * Research institutes should assist
private sector in this direction to remove any
bottleneck in this direction. * Production of
biopesticides should be subsidized to promote its
production and use on large scale. * Joint research
projects assisted by both private and public sectors
should be launched for development of problem solving
and market-oriented products. * Organically produced
agri-commodities should be given weightage in terms of
their value in markets to encourage the production of
crops grown under applications of biopesticides.
Coutesy: The
DAWN |
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Pakissan.com;
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