Biological control: A safe alternative
to pesticides?
It
is a dream of every food producer of the world to produce a qualitative and
quantitative food in his production area. But many constraints including soil
quality, fertility, genetically pure plant material, seed availability,
climate, market, pest disease, has been becoming a hurdles to achieve desired
food production with quality. Out of all these hurdles the impact of pest and
disease attack on crops is quite considerable and has greater effect on quality
and quantity of food produce. Insects has always been a certain interrelation
with this world, Their population is more than that of humans!!!!. They have
been affecting and helping to the humans, plant and other components of the Universe.
There are around Lakhs of insect-pest species exists in the nature and many of
them are very useful to human kind for e.g. Honey bee and many are harmful. “In warmer climates especially, insects can
spread devastating such as malaria, sleeping sickness, river blindness”( J.
Cooper H. Dobson,2007, p-1342). Accordingly to the Rose (2005) it is reported
that around 500 people are killed by malaria every day. Like humans insects
reduce the potential of the crop grown in the field by sucking, hatching,
different parts of crop.
Agriculture has always
been a major profession of major part of the world therefore many attempts have been made till date
including chemical, organic, biological control to manage the pest population
in the field. Accordingly to the John Kent (1991)”Pesticides (or farm chemicals, agro
chemicals or agvet chemicals) are those substances which are used to control,
destroy, repel or attract pests in order to minimize their detrimental effects.”
Different viruses, bacteria, fungi, weeds, insects, animal are referred as a
pests and all these may reduce the production and affect the quality of the
food produce. The pesticides can be categorized into the following classes:
1) On
the basis of chemical structure
a) Organochlorines
b) Organophosphates
c) Carbamates
d) Pyrethroids
e) Triazines
2) Organic
Pesticides
3) Biopesticides.
Chemical pesticides are
of chemical in nature and where as Bio pesticides have biological origin. In
Bio control of pests the existing population of living organism is reduced by
other living organisms. Under biological control, predators, parasites and
natural enemies are used to control the pests. “While the first recorded use of
chemicals to control pests dates back to 2500 BC, it is really only in the last
50 years that chemical control has been widely used” (Hock et al., 1991). But now a days it seems that
many farmers and people are moving towards the use of pesticides of biological
origin and may be because of people awareness. Chemical pesticides are having
several disadvantages. After
application of them over a crop they affect the nervous system of insect,
affect the metabolism, pigment system, affect the translocation of organic food
by affecting the phloem. There are some benefits behind using the chemical
insecticides, as they kill or repel the insect pest those causes the quality
and yield of the food produce. Many of the chemical insecticides are economic.
Apart from these benefits there is some hazardous effect of chemical pesticides
over a pests and crops since they cannot distinguish between pest and non pests
and may become harmful to useful organisms. After spraying chemical insecticide
they just kill any insects those come in their way. “Many of these
early chemicals had disadvantages. They were often highly toxic, were very
persistent, posing a threat to the environment, or they damaged the crops they
were meant to protect.”(Kent 1991). They often leaves residual effect behind
these residues left in food can contaminate poison to human, during spraying
they may damage to the crop, environment and other livestock. Weather condition
and the way of application of pesticide can affect the drift. While applying
chemicals over the crops if they are applied in excess and their leaching may
contaminate the irrigation water as well as ground water. It is very necessary
to take prevention method while spraying the chemical pesticides otherwise it
may affect adversely to the sprayer and may pollute the environment.
Table
no 1.
Table 1
2005 Global pesticide
market by region
|
North
America
|
8.60
|
|
Europe
|
8.74
|
|
Asia
|
8.16
|
|
Latin
America
|
5.65
|
|
Rest of
World
|
2.45
|
|
Total 33.6
|
|
Source: Allan Woodburn Associates/Cropnosis.
Table
no 2.
Estimated
sales of microbial and nematode biopesticides .
|
|
Sales Estimates
($)
|
|||||
|
|
North America
|
Europe
|
Asia and
Australasia
|
Latin America
|
Africa and Middle
east
|
Total
|
|
Total Bt.
|
72.75
|
26.77
|
43.12
|
14.45
|
2.48
|
159.57
|
|
Other bacteria
|
15.20
|
2.60
|
11.58
|
0.65
|
0.10
|
30.13
|
|
Viruses
|
1.03
|
5.45
|
5.33
|
2.89
|
0.55
|
15.25
|
|
Fungi
|
11.76
|
2.17
|
11.52
|
22.16
|
0.49
|
48.10
|
|
Protozoa
|
0.05
|
0.00
|
0.02
|
0.00
|
0.00
|
0.07
|
|
Nematode
|
8.25
|
6.00
|
0.37
|
0.03
|
0.00
|
14.65
|
|
Total
|
109.04
|
42.99
|
71.94
|
40.18
|
3.62
|
267.77
|
·
Produce based on B. thuringiensis serotypes.
“The past ten years have been marked
revival of interest in the biological method of insect control. It arose from a
growing realization that supplements and alternatives to chemical insecticides
are needed to overcome some of the faults and weaknesses now recognized as
Inherent in the chemical method of pest control”.( Bryan. P 1962, p-387). Many
people , farmers, agriculture industries are now realizing the hazardous effect
of chemical pesticides and therefore they are moving towards the adaption of biopesticides.
Because of the public awareness, demand for biopesticides is gradually
increasing in all over parts of the world. There are many advantages behalf the
biopesticides can be quoted like, if they are used as a part of Integrated Pest
management, they can show better result as compared to chemical pesticides.
Biopesticides since having a biological origin so do not leaves any residual
effect behind and therefore never can be harmful to the crops, humans and
environment. Unlike spraying of chemical pesticides they cannot be so hazardous
and provide more marginal safety to sprayers. Only closely related species and
generally target species are targeted by biopesticides. Since they are
biodegradable in nature so they will not cause any kind of risk to the surface
water as well as to the ground water. As compared to the conventional
pesticides they have less expectation of incurring development of resistance in
the target pests and it is because of their complex mode of action. The effect
of bio control is often consider as a permanent effect because of its self-
perpetuating and it can be the most advantage over a other method of pest
controls. Such kind of permanent effect may vary from different climate and region.
To obtain the effective result, it is necessary to have a well adequate knowledge
about the selection of most suitable species.
“In the recent decades, there has also been a significant increase in
the research and development (R&D) initiatives to promote the development
and adoption of biological control technology in India ” (S.Sithanantham,R. 2007,
p-1). In India Thrips has been a potential pest of many vegetables (eg. Chilli,
onion) Legumes (eg. Groundnuts) cereals (eg. Rice) spices (eg. Cardamom , turmeric.).
Accordingly to the Ananthakrishnan (1984) thrips causes a considerable crop
yield, growth and as well as vector of plant pathogens of crops. Several
predators are reported to provide natural control of thrips in India for eg.
Sing (1993) reported that feeding of Carayonocorsis
indicus and Orius maxidentex on Megalurothrips distalis. Research case
study of S.Sithanantham, R. shows that there is a great scope for the
conservation of natural enemies for thrips in tropical agrosystem.
Table no. 3
List of parasitoid of
thrips recorded in India.
|
Parasitoid
species
|
Thrips species
|
Crop
|
|
Ceranisus
sp.
|
Thrips
tabaci
|
Onion
|
|
Ceranisus
maculatus
|
Rhipiphorothrips
cruentatus
|
Grape
|
|
Megaphragma
longiciliatum
|
Frankliniella
lilivora
|
Grape
|
|
Thripastichus
gentilei
|
Rhipiphorothrips
cruentatus.
Gynaikothrips
uzeli
|
Grape
|
|
Thripobius
semiluteus
|
Panchaetothrips
indicus
|
Turmuric
|
“Biological
(bio) pesticides represent 2.4% of the global pesticide market, but this share
is growing quickly and is projected to double by 2010.”(Pamela G. Marrone
2007). On the contrary the market for chemical insecticides may decline because
of public awareness, govt. restrictions. In fact, in practically the chemical
insecticides are available at economic rate and there capitalization found more
as compared to biopesticides. However, the increasing perception level of
growers will leads to higher demand of biopesticides in future. Now a days it
has become a challenge before the growers to produce a qualitative and
quantitative food for fast increasing population. Therefore to avoid the losses
caused by pests, it is important to protect them with effective control
measures. And since chemical pesticides are so hazardous then only one option
would be the safe alternative to that and its obvious!!!!!!!!!!!!!!
Biopestcides.
References
PESTICIDES IN AGRICULTURE
Wagga Wagga. NSW 2678. (http://www.regional.org.au/au/roc/1992/roc1992031.htm)
Kent, J. (1991). Education and
training in farm chemical management. Proc. conf. Agriculture, Education and
Information Transfer. Murrumbidgee College of Agriculture, 1991.
Research
status and scope for biological control of sucking pests in India: Case study
of thrips.
S. Sithanantham, R. Varatharajan, Chandish
R. Ballal and P.N. Ganga Visalakshy.
Journal, Biocontrol, 21 (Special Issue) 1-19, 2007.
Barriers to adoption of Biological control
agents and biological pesticides.
By Pamela G. Marrone. 2007.
Trends in applied biological control of
insects,
By Brayan P. Beirne , 1962 p 387-400.
