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Biopesticides
Biopesticides are crop protection
products which have been designed for repeated
application, whose active ingredient is a
micro-organism such as a bacterium, virus, fungus,
microscopic nematode or microsporidium or part of a
micro-organism. These characteristics make them
attractive components for organic farming
practices. At the end of 2001, there were
approximately 195 registered biopesticide active
ingredients and 780 products. Biopesticides account
for about 20% of all pesticide active ingredients
registered in the USA.
Biopesticides fall into three
major categories:
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Microbial pesticides such as
Bacillus thuringiensis or Bt. Each strain of Bt
produces a different mix of proteins which can
specifically kill one or a few related species
of insect larvae. While some Bt’s control moth
larvae found on plants, other Bt’s are specific
for fly or mosquito larvae. The Bt produces a
protein, which is ingested by the insect. The
protein binds to a gut receptor causing the
insect larvae to starve to death. About 60-90%
of the global biopesticide market can be
attributed to Bt.
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Plant-incorporated-protectants
(PIP’s) are pesticidal substances produced from
genetic material which has been added to a plant
(e.g. Bt Cotton). The gene that codes for the
Bt pesticidal protein can be introduced into the
plant’s genetic material allowing the plant to
then produce the Bt toxin.
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Biochemical pesticides are
naturally occurring substances that control
pests by non-toxic mechanisms. Conventional
pesticides are synthetic materials that can
directly kill insect pests.
General Qualities of Effective
Biopesticides
The qualities of an effective
biopesticide are similar to that of a chemical
pesticide: they must work with good efficacy
against the pest for which they are labeled. There
has been considerable consumer and governmental
pressure to minimize the use of chemical
pesticides. This can be seen by the desire of the
consumer to purchase organic produce and by
supermarkets demanding that growers utilize
environmental sensitive crop production strategies.
The unique value for biopesticides is based on the
three “R’s”:
Resistance management
Since biopesticides have
multi-modes of action, there is less chance of
developing resistance in a particular insect.
Biopesticides can be an excellent component of an
integrated pest management (IPM) program. An IPM
program involves a grower applying two or three
chemical pesticides and then using a completely
different product to vary the mechanism of action.
Through government, supermarket and consumer
pressure, IPM is becoming increasingly established
as the future of crop protection.
Restricted entry intervals
Restricted entry intervals (REI’s)
determine the timing of application relative to a
number of factors. The majority of biopesticides
have low REI’s, mostly around 0-4 hours with no
pre-harvest interval. After a biopesticide is
applied, a farmer can go into the field and harvest
immediately.
Residues
Residues are a regulatory issue
with pesticides. The Environmental Protection
Agency (EPA) has jurisdiction over their proper
application. The Office of Pesticide Programs of
the EPA has established a Biopesticide and Pollution
Prevention Division (BPPD). This group helps to
coordinate the registration of biopesticide products
(www.epa.gov/pesticides/biopesticides). Since
biopesticides tend to pose fewer risks compared to
conventional chemical pesticides, the EPA generally
requires less data to achieve new product
registrations (< 1 year). Conventional chemical
pesticides can take up to three years for regulatory
approval.
The ‘risk cup’ system places a
limit on the total, cumulative, potential exposure
to a pesticide across all of its applications. This
system has forced companies to make the choice
between registering specific agrochemicals solely
for use on major crops, or to limit their use on
major crops to enable their use on a larger number
of less widely grown crops. Unsurprisingly,
agrochemical companies have focused their
registration of new pesticides on the high acreage
field crops. Many have also taken the decision not
to support older products through re-registration of
high value niche crops. The USDA Inter-Regional
Project No 4 (IR-4) program is helping to support
the registration of crop protection products on
minor crops by carrying out some of the trials
required for completion of a registration dossier,
with the support of the relevant company. This
government initiative has helped to limit some of
the crop protection product availability problems
faced by minor crop growers but has not entirely
prevented a shortfall in crop protection product
availability in some minor crop sectors.
The cost of registration of a
biopesticide product is usually an order of
magnitude less than for a chemical pesticide
product. In the US, the cost of registration of a
biopesticide can usually be measured in hundreds of
thousands of dollars. In contrast, registration of
a chemical pesticide costs millions of dollars. This
reflects the regulator’s preference for
biopesticides, especially Bt products. Because of
high chemical registration costs, many high value
crop and niche markets are now being left without
effective chemical crop protection solutions,
leaving Bt as the economical choice for many
producers. These markets represent a growth
opportunity for InsectiGen™.
Additional qualities of
biopesticides
Some other feature of
biopesticides include: narrow target range,
specific mode of action, slow-acting, safer than
chemicals, limited field persistence, high unit cost
of biopesticide production and they suppress but do
not eliminate pests.
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