est Control - Government of Kerala

Consumption of pesticides in
India
Year Quantity
( Thousand Tonnes)
1994-95 61.36
1999-00 46.20
2004-05 40.67
2008-09 43.86
Source: Department of Agriculture and
Co-operation, New Delhi
Pesticide consumption in India for
agricultural purpose is 288 g/ha, while
the global average is 900 g/ha. Andhra
Pradesh and Punjab consume 47
percent of total pesticides. Cotton
consumes 45 per cent of pesticides used
in the country followed by vegetables/
fruits(13-24 per cent) and rice(20 per
cent).
The export of the pesticides have
shown a growing trend. The export
earning was Rs.2010 million in 1993-94,
which rose to Rs. 10000 million in 1997-
98 and 16000 million in 2000-2001.India
exports synthetic Pyrethroid,
Chlorpyriphos and few other pesticides.
Resistance to Insecticides
The occurrence of pesticide
resistance in India was first noticed in
insects of public health importance. Large
amount of insecticides used under the
National Malaria Control Programme
from 1948 to 1960 resulted in the
development of insecticide resistance in
insect vectors of human diseases. In
agriculture, development of resistance
appeared comparatively later because
appreciable amount of insecticide was
used from 1970 onwards on agricultural
crops raised using high yielding varieties,
irrigation and fertiliser. Insecticide
resistance occurs as a result of
inappropriate and largescale use of
pesticides particularly at sub lethal doses,
repeated application of the same
pesticide or similar group of pesticides
over a period of time as well as under
36 KERALA CALLING July 2011
dosing due to substandard pesticidal
formulations. The application of
pesticides may also bring resurgence of
target pests against which the chemicals
are applied and also lead to the outbreak
of some pests hitherto unimportant. The
introduction of lindane to control the
aphids as well as boll weevil led to
outbreaks of mites due to destruction of
natural enemies.
The modernisation of agriculture
have directly or indirectly led to
increased incidence of pests and
diseases. Monocropping, continuous
cultivation of commercial crops,
reduction in area of coarse cereals, minor
millets etc. have raised many minor pests
to the level of major pests. The number
of insect pests that were considered
important in paddy cultivation increased
from three in 1965 to more than 13 in
1995.
Pesticide Residues
Pesticides are required during
production, processing, storage and
distributionof food. Thus food contains
unavoidable residues of pesticides. Even
in areas far away from the site of
application pesticide residues esp.,that
of organochlorines have been found
dominating. Similarly bioaccumulation
of these chemicals in milk, butter, meat
and even human fat has been observed.
Studies revealed that 86 percent of soil
samples collected from agricultural lands
of Punjab were contaminated with DDT,
HCH, endrin and lindane. Residues of
DDT have been detected in Yamuna and
Ganga. In UK the presence of insecticides
was reported in rain water. Snow from
Arctic was found contaminated with
insecticidal residue.
Earlier it was generally assumed that
dilution in environment was a
satisfactory answer to pesticide pollution.
Today it is known that organochlorine
compounds can persist in soil and water
for periods of years to decades and they
can be biomagnified in the tissues of
invertibrates, fish, birds and mammals.
The rate of disappearance of residues of
insecticides is expressed in terms of half
life, which is the time required for half of
given quantity of material to dissipate.
The half life of DDT is 3-10 years and that
of heptachlor, lindane and dieldrin are
7-12, 2 and 1-7 years respectively.
The most economic insecticides
have combined broad spectrum insect
toxicity with extended persistence in the
environment. This combination is now
regarded as undesirable, and broad
spectrum activity must be combined with
limited persistence.
The pesticides are also harmful to
beneficial fauna such as honey bees and
natural enemies like parasites and
predators. The danger of pesticides to
bees comes not only from direct contact
poisoning, but also from the taking pf
poisoned nectar into hives.