Deadly drugs
There are three classes of pesticides, and they kill the
critters in very distinctive ways:
Neurotoxicants:Neuroactive compounds, like DDT and
pyrethroids, directly affect the nervous systems of the
creatures.
GABA agonists: The avermectins affect invertebrates by
disrupting their nerve impulses. Consequently, the insects
are paralysed irreversibly and stop feeding.
Nicotinyl Insecticides: Nicotinyl insecticides interact
with nicotinic acetylocholine receptors (nAChR) at
the central and peripheral nervous systems
resulting is paralysis, followed by death.
And their deadening impact…
Nearly all these chemicals have the potential to
significantly alter ecosystems. In fact, many are toxic to
human beings, and others are concentrated in the food
chain. So, are we really being able to balance agricultural
needs with environmental and health issues while using
them? Think about it...
In our frenzy to get rid of pests we tend to overlook
the fact that these poisons have a massive fallout on
critical components of our ecosystems. Pesticides use
water, soil and air as carriers and get deposited in bodies
of living organisms. Bird species are the worst sufferers.
They feed on poisoned insects and the deadly chemicals
are concentrated in their internal systems, resulting in
infertility and even death. Vultures, that feed on infected
cattle carcasses, have virtually disappeared from urban
skies.
Fish, birds, and wildlife that live in direct contact with
environments subject to pesticide exposure are sentinel
species that may be predictive of our own fate. To
understand this more clearly let’s find out how a pesticide
behaves in soil and in water.
Venom in water
There
are broadly two ways pesticides reach surface and ground waters
-- through runoff and leaching. Runoff is when pollutants enter
rivers, lakes and other water bodies via the medium of rainwater.
Leaching is a process by which pollutants are flushed through the
soil by rain or irrigation water as it moves downward. This way
they penetrate the surface, and contaminate ground water. In many
areas, soils are sandy and permeable and leaching is likely to be
a more serious problem than runoff.
Bad lands
Once applied to cropland, a number
of things may happen to a pesticide.
It may be taken up by plants or
ingested by animals, insects, worms,
or microorganisms in the soil.
Worldwide, extensive studies have
shown how the pesticides affect the
soil health by killing the vital microbial
fauna present in the soil. Each gram
of soil may contain millions of
microbes, which are important to
sustain plant life. Pesticides not only
kill these microbes, they persist in the
environment and have been observed
to accumulate in the food chain. It is
due to their tendency to accumulate
in the animal fatty tissue, and move
up the food chain, that their residues
have been found in the mother’s
milk.
Health hazard
Now if the water, the soil, as well as
the air is contaminated by this poison,
how can our bodies remain immune
to it?
Pesticides that enter the human
system through these carriers ravage
our metabolism. As per intensive
surveys conducted in different
parts of the world, they are now
known to cause lethal diseases
ranging from several forms of cancer,
liver damage, and reproductive
disfunction to neurological disorders
like Parkinson’s and Alzheimers.
Going organic
But here is some good news. Many
farmers, across the world, are turning
to biological management of farms.
They are supported by agricultural
scientists who have studied the preypredator
relationship between
various species of insects that are
major pests and used the same
process to control impact of insects
on farm yield. They are also
experimenting with certain natural
substances that also act as
insecticides without posing threats to
the ecosystem like a chemical
product.
Today many farmers across the
world are practicing organic farming.
And their produce fetches a higher
price than conventional farm
products. Some organic farmers have
even proved that there is no drop in
the yield due to use of organic
substances. However in India, organic
farming is still tried out at a miniscule
scale. Big farmers who grow cash
crops are reluctant to try it out. More
help from the government in the
form of financial incentives or
investment in specific research may
do wonders to this practice.
Man, woman and…insects!
Ancient India, in fact, had perfected
the art of dealing with pests, without
endangering the rest of the planet.
And some smart researchers have
picked up these tips and are
practicing it today…
A Karikali-based group in Tamil Nadu calls itself a university with
multifarious ecological roles — Vazhviyal Multiversity. The herbal
pest repellant it produces is based on traditional knowledge listed
in the scripture — Vriksha Ayurveda. It is prepared from the leaves
of five plant species that are not eaten by cattle. These can vary
from place to place, but would ideally include neem, tulsi, and
datura.
The truth is, neem, tulsi and
turmeric powder have been used as
insect repellants in Indian homes
since ages, and this is still a common
custom in scores of rural households.
Go explore
So it’s a world of fascinating
details…some times bordering on the
macabre. Try and find out more
about insects present at your home
and school.
What you find will be quite an
eye-opener. You will find that all of
them perform some function in our
ecosystem and if we eliminate them
we have to perform their functions
to maintain the balance in our
ecosystem.
It is for you to decide whether
we have the right to eliminate such a
magnificent order of organisms? Can
we change our approach towards
insects? Can we change the ways we
manage our conflict with the insect
world? There are just questions and
more questions.
So, can we get some answers on how we can deal with insects at panditji@cseindia.org? |
