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| Biopesticides - Road to Agricultural Recovery |
| SK Brar1*, S Kaur2, GS Dhillon1 and M Verma3 |
| 1INRS-ETE, Université du Québec, 490, Rue de la Couronne, Québec, Canada |
| 2Department of Mycology & Plant Pathology, Institute of Agricultural Sciences, Banaras Hindu University (BHU), Varanasi-221005, India |
| 3Institut de recherche et de développement en agroenvironnement inc. (IRDA), 2700 rue Einstein, Québec (Québec), G1P 3W8, Canada |
| *Corresponding author: |
SK Brar, INRS-ETE
Université du Québec
490, Rue
de la Couronne
Québec, G1K 9A9, Canada
Tel: 001-418-6543116
E-mail: satinder.brar@ete.inrs.ca |
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| Received May 13, 2012; Accepted May 15, 2012; Published May 17, 2012 |
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| Citation: Brar SK, Kaur S, Dhillon GS, Verma M (2012) Biopesticides - Road to
Agricultural Recovery. J Biofert Biopest 3:e103. doi:10.4172/2155-6202.1000e103 |
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| Copyright: © 2012 Brar SK, et al. This is an open-access article distributed under
the terms of the Creative Commons Attribution License, which permits unrestricted
use, distribution, and reproduction in any medium, provided the original author and
source are credited. |
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| The dawn of human civilization came with the need of producing
and safe guarding food for sustaining current and future generation.
The growth and development in living standards came with incessant
changes in agriculture often based on novel introductions, ethical
beliefs and the end users preferences. Agricultural intensification
became a matter of concern in order to support the growing population
and ensuring the per capita availability of food grains. Losses due to
insects and pests are often hampering the agricultural production.
Insect pests are a major constraint on production of many crops
worldwide. Traditional reliance on agro-chemicals from decades has
led to environmental pollution, toxicity, bio-magnification and the
development of resistance. Due to which several chemical pesticides,
such as organochlorine and methyl bromide have been staged out.
Increasing number of pesticide and fungicide resistant strains has
become a matter of serious concern. The global consent to alleviate
the use of chemical pesticides is gaining substantial importance in the
perspective of the development of novel, benevolent, and sustainable
crop protection strategies, such as the use of biopesticides. |
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| One of the most insurgent contributions of science to the plant
disease management is the development of Bacillus thuringiensis (Bt)
based biopesticides and thereafter transgenic Bt crops. The growth
and development of Bt based biopesticides in the past and future has
covered an extensive area of research from dual culture to spacious
arena of omics i.e., molecule to functional genomics. The genomic
constitution of Bt conveys enthralling properties, such as an array
of entomotoxin active against diverse insects against root dwelling
pests, or larvae that after hatching rapidly burrow or bore into plant
tissues. More to the point, the crops are frequently affected by different
pests that are unable to be controlled by a one Bt product alone. Bt
crystal proteins are UV sensitive and degrade rapidly thereby losing
their activity. Therefore, several applications are required through the
entire growing season that invariably increases the cost of application.
Technological advancements have led to the development of advanced
Bt formulations that are more adaptive to harsh environmental
conditions. |
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| In our efforts to minimize the damage caused by insect pests,
we have to acknowledge that pests cannot be efficiently managed
by utilizing a single pest control agent. Several studies have shown
that pest resistance to chemical pesticide and more recently to Bt
has increased requiring new techniques to be applied to reduce the
impacts of pest on crop production. While commonalities regarding
the development of resistance to chemical and biological control agents
remain to be determined, research suggests that both biochemical and
genetic factors can contribute to this resistance. In the present context,
the biopesticides have gained importance meticulously in permutation
with Integrated Pest Management (IPM). It is therefore crucial to
continue examining the potential of IPM to reduce the threat of pests
on agro-ecosystems. |
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| IPM is a technical and systematic concept which is now of
inclusive implications. Elementary meaning of IPM is designing and
implementing pest management practices while fulfilling the basic
goals of farmers, consumers as well the governments in minimising the losses due to pests. It also curtails the risk of environmental pollution,
human health hazards, whilst improving the agricultural sustainability.
However, the philosophy of IPM is now widely acknowledged in
the political as well as scientific community. Biopesticides as a key
component of IPM has the potential to lessen the use of conventional
pesticides to a great extent while improving the crop yields. |
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| The key success of biopesticides lies in its impact on the target pest,
market size, and variability of field performance, cost effectiveness, and
end-user feedback. Technological challenges such as, fermentation,
formulation development and efficient delivery system also affects the
success of any biopesticide. In spite of the fact that Bt biopesticides
has undergone extensive research, several formulations do not deliver
effectively under field conditions. Integrated approach, i.e., the
development of biopesticides that also supports sustainable agriculture
can further strengthen its role in plant disease management. Adapting
cost-effective fermentations, using conventional and simple adjuvants/
additives, and efficient harvesting processes might lead to the
development of high potent efficacious formulations that are also
widely accepted. Activity spectrum, persistence, recycling and cost-
effective formulation development needs to be addressed in order to
establish the biopesticides in an international market particularly to
the farming community. Recently, the concept and theories for using
wastewater, wastewater sludge and other agro-wastes as a potential
cost-effective technique for Bt formulations have become widely
accepted and extensive research has been carried out in the past one
decade. |
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| The emerging era of insect-resistant transgenic Bt crops also
offers real prospects to provide a foundation for more sustainable,
economically acceptable IPM with the integration of a range of non-
chemical tactics and much less reliance on pesticides. Introduction
of Bt transgenics since last one and half decade, opened spectacular
approach of introducing host plant resistance with magnificent
socio-economic gain. With the increase in the search of crop species
expressing different cry genes are developed, the first generation
of insect-resistant transgenic Bt crops will most likely increase.
Nonetheless, pests tend to modulate their level of resistance either by
loss or gain of function approach and remain tolerant of the available
Bt toxins. Transgenic plants expressing Bt toxins were among the
foremost plant biotechnology products approved for commercial
purpose. Nevertheless, it was implicated that Bt toxin might affect non-target organisms, such as predators or parasites and may lead to
develop resistance owing to high selection pressure. |
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| RNAi (post-transcriptional control mechanism) in the form of
transgenic plants or a crop spray has a robust and selective effect on
target gene expression that makes it a valuable tool for manipulating
metabolic pathways and the above mentioned problems. The level
of RNA silencing produced is considerably affected by constructing
a suitable vector/expression system and delivery method. Vectors
containing inverted repeats separated by an intron produce doublestranded
RNA (dsRNA) or hairpin RNA (hpRNA) which effectively
inhibits homologous gene expression at the RNA level. The specificity is
sequence based and depends on the sequence of one strand of the dsRNA
analogous to part or all of a specific gene transcript [1]. Fabricating
dsRNA in RNAase III deficient E. coli strains and treating the plant
with the extracted product as an alternative to RNAi transgenic plants
has recently been accomplished [3]. Point to be emphasised here is
that RNAi is a knockdown instead of knockout effect that suggests that
total silencing does not takes place and the effect could be frequently
ephemeral [2]. Although, it should not be an insuperable drawback to
use this technique as under many circumstances, partial silencing of
certain genes might result in irreversible negative and lethal effect on
the insect. |
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| Even though it is implausible that RNAi have an instantaneous
effect on crop protection against lepidopteran and coleopteran pests,
however Bt-based strategies propose a high degree of protection. The
technology finds an appropriate place where Bt-based approaches is
difficult to achieve such as, in the case of dipterans (flies) or where
no effective Bt toxins are known, example sap-sucking homopteran
pests (aphids, leafhoppers and whitefly). In order to target these phloem-feeding insect pests, in planta expression and transportation
of dsRNAs in the phloem sieve elements is the primary requirement.
Similar to any other control methods, risk assessment will be required
to determine whether transgenic crops or RNAi technology as a form
of pest control will be safe and probably create a new era in pest
control. Therefore, an extensive research is required to introduce a
feasible technology that is also readily acceptable and available to the
entire farming community for plant disease management. At the same
time, it should be cost-effective and self-sustainable to fit the changing
trends of agro-ecological systems. Although there is an enormous
possibility to control many pests, in agriculture and forestry through
Bt based technologies, there is still some research required in terms that
inculcates their efficiency across the globe under diverse agro-climatic
and ecological conditions. It needs the inputs from the entire scientific
community through the farming community, stake holders, and
extension development officers, to share and exchange their paragon
together on one platform. Therefore, it is necessary to disseminate the
knowledge of pest management in an eco-friendly manner to the end
users by propagating biopesticides which will bestow a sustainable
future to the agriculture. |
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| References |
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- Borgio JF (2010) RNAi mediated gene knockdown in sucking and chewing
insect pests. Journal of Biopesticides 3: 386-393.
- Shakesby AJ, Wallace IS, Isaacs HV, Pritchard J, Roberts DM, et al. (2009)
A water-specific aquaporin involved in aphid osmoregulation. Insect Biochem
Mol Biol 39:1-10.
- Yin G, Sun Z, Liu N, Zhang L, SongY, et al. (2009) Production of doublestranded
RNA for interference with TMV infection utilizing a bacterial prokaryotic
expression system. Appl Microbiol Biotechnol. 84: 323-333.
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