Conservation and augmentation of spiders in the fields is a simple, yet efficient method of pest control. Spiders are predators of pests like thrips, caterpillars, aphids, plant bugs, leaf hoppers, flies, etc. Their importance as pest control agents is not a recent discovery. On the contrary, their value has been acknowledged by farmers from time immemorial. Several ancient books on agriculture mention their importance. In China, even to the present day many elderly people in villages take the number of spiders in a field as a measure of its potential agricultural productivity. Fields abundant in spiders, prior to the introduction of chemical pesticides are now witnessing a change in the scenario. In addition to killing pests, these chemicals are also taking a heavy toll on useful insects. Preservation of spiders necessitates abandoning of these pesticides, or spot treatment and rational use of the same. Once pesticides are kept away from the fields, spiders invariably take shelter in the fields, feed on the pests and add to the productivity.
Spiders have always been known to be effective predators, though their potential as biocontrol agents has not been exploited to its fullest, at least in India. By detailed research in this field, and a series of awareness and training programmes, we aim to propogate the use of spiders as a feasible method of pest control.
Besides documenting spiders present in rice fields and studying effects of pesticides on some of these spiders,no systematic study on rearing of spiders for use in biocontrol has been attempted. CIKS is at present attempting to realise the biological control potential of spiders for control of a single pest or of a complex system of pests,studing them in the agroecosystem itself. Investigating the interactions among crops, pests, natural enemies, soil and climatic factors, cultural practices that are used is also an important aspect of our research.
What we have already achieved?
Mass rearing technologies have been developed for Giant Crab Spiders (Heteropoda venatoria) which feed on the cockroach,one of the most troublesome pests known to man. It has been established that having 2-3 of these giant crab spiders in a house of about 600 sq.ft can keep the cockroach population under fairly good check.
Rural women and youth have been provided training in these rearing technologies.
Mass rearing technologies for important paddy-ecosystem spiders- the green and brown lynx spiders- have been developed.
For the past several years, CIKS has been using plant extracts and spiders as biocontrol agents as an alternative to synthetic chemical pesticides to control pest populations. It has been established that spiders and natural products can be used in combination to control a wide variety of pests in the paddy ecosystem.
|STUDYING SPIDERS IN THE COTTON ECOSYSTEM
One of our more recent projects is to study spiders occuring in the cotton crop, document them, estimate their value as useful predators and understand their ecological significance in this ecosystem.
Spiders have been found to be the most abundant group of predators in the cotton ecosystem,constituting by numbers upto 60% of the predacious athropods in cotton. They have been shown to be important organisms that control major pests that affect the cotton crop.
The current study will study spiders and estimate their numbers in a field where cotton is grown completely organically. A comparative study will be made in a field cultivated inorganically.
One of the objectives of the study is also to bring out a booklet for identification of species that can be found in the cotton ecosystem.
ECOLOGICAL STUDY OF SPIDERS IN GUINDY NATIONAL PARK, CHENNAI.
Our study in GNP to document the spider fauna of the park and to analyse the impact of disturbance within the park on their population.
Excerpts from the report.