Any crop
ecosystem contains a balance of community of organisms living in harmony with
the environmental factors. Community of organism is the food web prevailing in
the place in order to facilitate decomposition and nutritional cycle. The
balance is maintained according to the non-biological factors like temperature
and moisture. The process of adaptation and survival of the fittest are in full
swing. In agriculture, the natural balance is disturbed and importance is given
to the prolific growth of any one or more crop which is of economic importance
or human interest. In such situations, a new ecosystem is developed for any
particular cultivation – Paddy ecosystem, pulse ecosystem, wheat ecosystem.
Paddy ecosystem consists
of Paddy crop, the soil, the microbes dwelling in the soil which decomposes the
crop residues and determines the fertility level of the field, group of insects
– live on paddy for their survival (Pests) and organisms feed on pests. Pest is
any organism causes economic damages and hindrances for the existence of crop
or human being. Pests in agriculture causes damage to the crop growth and
either kills the plant or create economic loss by drastically reducing the
yield.
By encouraging
the growth organisms which feed on pests we can effectively keep the pests in
control in a natural way. They are called Natural Enemies. They are the real
heroes in keeping the agricultural scenario pesticides-free. They facilitate death, weakening, or reduced reproductive potential of harmful
pests. The commonly visible natural enemies are insects and spiders, they feed
on plant feeding insects and protect crop from economic loss. Natural enemies
can be classified into two broad types – Predators and Parasitoids.
Predators
Predators
consume one or more living prey insects. Predatory behavior is common in
insects, spiders and mites. Common predators are spiders, mites, ladybird
beetles, dragon fly, and bugs. The diversity of predators in agro-ecosystem is
enough to keep pests in control. When predators could not keep pest population
below economically damaging levels, they actually slow down the rate of pest
population increase. But the pesticide usages have disturbed the balance of
such Biological shields of crop. Predatory insects, spiders and mites feed on
any or all stages of their prey, by killing, disabling eggs, larvae, nymphs,
pupae or adults.
- Beetles chew their prey.
- Bugs inject toxins into their prey and immobilize, later suck their juices.
- Dragon flies catch their prey in flight
- Praying Mantis wait for their prey, camouflaged and catch their prey by surprise.
- Spiders trap many pests with their web and consume later.
- Hover flies hover and dart in flight.
Parasitoids
Parasitoids live
in or on the body of their host insect during at least part of their life
cycle. Parasitoid is the term used to describe an insect that parasitizes and
kills its insect host. Endoparasites insert
their eggs into a host’s body. Ectoparasites
lay their eggs and their larvae
develop on the outside of the host’s body.
A typical female
parasitoid searches
Field release of
egg parasitoid Trichogramma japonicum at weekly intervals during egg laying
stage of rice borer in very effective as the parasitoid kills the pest in the
egg stage itself before the pest could cause any damage to the crop.
Trichogramma chilonis at weekly intervals keep leaf folders on control as the
parasitoids lay its egg in stem borer larvae hence kill the pest, multiplies
themselves and spread rapidly. It is very economical as the Tricho-cards are
low cost inputs. Cost involved to control the pest otherwise is detrimental
both economically and environmentally. Let us choose a GREENER way of pest
control to live longer healthily.
Nice info! Keep writing often!@
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