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Kerala farmer uses red ants to fight cashew bugs

Tea mosquito bug is the most serious pest of cashew plantation.

An accidental discovery by a farmer that red ants could replace the use of pesticide to contain the attack of tea mosquito bugs in cashew plants,has prompted the Kerala Agricultural University in Kasargode to refine the ant technology for larger field application.

Entomology Department of the university has begun a three-year project on the use of red ants in vegetable cultivation to do away with the use of pesticides to curb the insects,apart from continuing the experiments in the cashew sector.

N Vasavan,a small-scale farmer in the district,had brought back the ant-based biological pest control in his cashew plantation when the farm sector was heavily banking on pesticides. Tea mosquito bug is the most serious pest of cashew plantation. To contain the bug threat,endosulfan had been aerially sprayed in the government-owned large tracts of cashew plantations for two decades. Researchers say the adult and nymph of the bug suck the sap from tender shoots,cashew nuts,fruit and other areas,reducing the output by 50 per cent. A single nymph can cause blighting of tender shoot within four days of feeding.

A school dropout,Vasavan planted a new variety of cashew saplings in his small holding in 2004. After two years,red ants had formed their colonies in a few plants. When tea mosquito bugs began attacking the plants,Vasavan used a local concoction of bio-pesticide made out of neem cake and garlic. “The ants perished due to the bio-pesticide. Later,I avoided the plants where the ants had formed nestles within the leaves,’’ said the 55-year-farmer. He was surprised to see that the trees where ants had harboured were growing better than those treated with pesticide. Soon,Vasavan started grooming ant colonies in his cashew shrubs.

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He also happened to read an article in a magazine by Dr K M Sreekumar,an entomologist who threw light into the use of various ants to control pests several centuries back. Vasavan apprised Sreekumar about his experiment.

With the aid from the State Planning Board in 2007,the duo began steps to prove that adoption of ant technology could control bug menace in cashew plants. For the next three years,Vasavan’s 3.16 acres of land,where cashew plants grew,was converted into a lab.

The study found that the population of tea mosquito bugs as well as the damage inflicted were significantly lower in ant-treated plants for three years. By the fifth year of planting,ant-harboured plants produced four times higher yield compared to untreated plants. In ant-harboured plants,production extended up to June whereas in untreated plants,the yield was only up to April. The number of unproductive shoots was higher in the untreated plants compared to the ant-harboured plants in 2008 and 2009. The study,presented in the Kerala Science Congress in 2010,recommended that the red ant technology was a viable option for pest management in cashew.


Sreekumar said,“Grooming red ant habitats in cashew plants would help increase production by five times.’’

Vasavan said human intervention is required at the initial stage to make ant colonies. Using a rope,cashew plants could be connected with the trees having ants’ presence. Dried fish could be used as bait. Vasavan has been honoured by the government agencies for his innovative pest management system.

First published on: 29-07-2011 at 03:36:29 am
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