Assam farmers’ worst enemy

 A caterpillar that flourishes after floods is causing an economic havoc. It could mean devastation for the farmer and his crops if the insect is not stopped from proliferating.

The floods in Assam lead to miseries in different stages. Much after the waters recede, leaving people to piece together their lives after the devastation, disaster strikes again. This time in the shape of a caterpillar that thrives after floods and begins attacking crops.

 The rise of temperature in the aftermath of flood leads to explosion in population of the Rice Swarming caterpillar (Spodoptera mauritia) in the affected districts of Assam. A prolonged draught increases the activities of the pest. In the event of flood at initial stage they are carried away and then it feasts on the rice plant.

 The insect has taken a heavy toll on the standing paddy crops across 22 districts of the state. Unfortunately for the farmers, the caterpillar survives in floods as well in high temperatures. And, it wreaks havoc in a short span of time. Even worse, in favourable conditions its population proliferates.

 “The flood water helps disperse the worm across inundated areas. At this stage, the caterpillar devours gregariously marching in a body from one field to another and laying eggs in 25 to 30 days,” says Dr D N Kalita, the Programme Coordinator of the Krishi Vigyan Kendra in Kamrup.

The nocturnal worms stay active from June to September, and as temperatures dip they hibernate. During day they go into hiding amidst the grasses including at the base of crops. Eradicating it completely is not the answer. “Given the role of any insect in the ecosystem service that is not the solution. Managing its population to cut down its economic damage is the answer,” says Dr Kalita.

 Dr Kalita says a proper cropping sequence could be an effective deterrent to the caterpillar increasing its population. His recipe is that post paddy cultivation should be followed by mustard and green manuring crops. This would stop proliferation of the dreaded insect. An Integrated Pest Management is necessary to keep the eco-system balanced and chemical agents should be the last option, says the expert.

If Assam's farmers are to save their crops it's essential that there is regular pest monitoring. Early detection of pest means insecticide can be applied locally without any adverse effect on the environment. Monitoring at the initial stage is productive because the pest at that time is among weeds, their most preferred hosts. This is an experiment that has worked well in Orissa, a leading paddy growing state. An "E-Pest Surveillance" project in the 13 districts of Orissa during the kharif season found that infestation of the swarming caterpillar was below the Economic Threshold Level in most of the districts.

Nayan Kumar Bora, Agriculture Officer with the Integrated Pest Management, says monitoring of cropland at the initial stage in April-May is of paramount importance because it's much easier to control the pest at that stage. “The larvae is unable to swim. To eliminate the larvae from the flooded fields under cultivation a small amount of kerosene is poured. when the plants are shaken vigorously the larvae fall into the kerosene-mixed water which is a deathtrap for it." 

As for cultural control, farmers are required to undertake both pre-plantation and post plantation management of the land under cultivation. At the beginning of tilling activities, the land is subjected to massive ploughing. The insect comes out once the ploughing is deep and then it is easy prey for birds. Duck will nuke the caterpillars if they are allowed to swim in the field.

 Experts blame the state machinery for not training farmers to deal with the swarming caterpillar situation at the initial stages itself. Much of the collateral damage can be avoided if farmers are given the knowhow, they say. 

 First seen as a minor problem for rice growers in India, the caterpillar has emerged as a serious pest over the past decade. And, it's not just rice that the insect attacks. At equal threat is maize, oat, cabbage, cauliflower, broccoli, mustard, sugarcane and wheatgrass. if not checked, it can cause havoc as Assam is already witnessing.

Kishore Talukdar

(Kishore Talukdar is an independent journalist based in Guwahati. His areas of interest include Development journalism and Environment journalism. He can be contacted at [email protected] )