Surinder Sud: From bollworms to mealy bugs

FARM VIEW

Thanks to pesticide usage falling with Bt cotton, another pest is assuming menacing proportions.

Woes of the cotton growers seem to be unending. While the threat of annihilation of their crops from the dreaded American Bollworm has abated thanks largely to the availability of pest-protected transgenic Bt-cotton hybrids, another pest is threatening to become as menacing as the bollworm. This is mealy bug, a plant sap-sucking insect having various species, some of which have multiplied to assume perilous proportions chiefly because of the reduction of pesticide use after the spread of Bt-cotton.

A significant presence of these white-coated insects, viewed earlier as merely minor pests, was observed on the cotton crop in Gujarat in 2006 and, subsequently, in Punjab and the adjoining northern cotton-growing tracts in 2007. There have been reports of its growing populations from most other cotton-growing states as well. In 2005, the mealy bugs had destroyed almost the entire cotton crop in several parts of Pakistan, notably in Multan, Sanghar, Mirpurkhas and Tandu Allahyar areas.

What is worse, entomologists feel that if preventive action is not initiated immediately, the pest may cause extensive damage to the next cotton crop to be planted from April onwards. For, a good deal of pest load already exists in the cotton belts. Apart from cotton, this pest can also pose hazards for other commercial crops, including grapes and jute and mesta, where it can lead to 50 to 100 per cent yield loss.

Fortunately, the agriculture ministry has taken the forewarning by the scientists of the Indian Council of Agricultural Research (ICAR) with the seriousness it merits. It has, consequently, prepared a programme for creating awareness of the mealy bug menace and to educate farmers on the ways of combating it. The scheme, costing Rs 130 lakh, will be implemented from the coming kharif season itself.

According to O M Bambawale, director of the New Delhi-based National Centre for Integrated Pest Management, the widespread cultivation of Bt-cotton, which had resulted in substantial yield gains, had also led to a change in the overall pest scenario. Instead of bollworms, several other pests were threatening the crop now. These include parawilt, grey mildew, mirid bugs, mealy bug, thrips and the like.

The mealy bug insect, indeed, is different from most other pests in several respects which pose special problems in combating it. The most significant "" as also, perhaps, odd "" among them is that males are not necessary for reproduction in mealy bugs. Female adults lay, on their own, around 400 to 600 eggs which are capable of growing into young mealy bugs called crawlers, because of the way they move about, within three to nine days.

Besides, on maturity, these insects acquire a cottony look because of their soft bodies that get covered with white mealy wax, making them virtually indistinguishable from cotton. Moreover, when the cotton plants are not in the fields, these pests can survive, and even thrive, on several other plant species as also on the cotton sticks and other parts of the plants which are generally kept by the farmers for use as fuel. These pests, because of their sticky nature, can travel to distant places by clinging on to farm equipment, animals or even people and agricultural workers moving from one place to another.

Indeed, both young ones and adults are enemies of the plants. By sucking the sap from leaves, they cause withering of leaves, stunting of plant growth, and premature dropping-off of cotton bolls. In the case of heavy infestation, the pest can totally denude the plants of leaves, leading to their demise.

Worse still, no mealy bug-resistant cotton varieties or hybrids are available as yet. Pesticides need to be sprayed five to six times to control the pest. These cost over Rs 3,500 a hectare, which many farmers can ill-afford. Experts are, therefore, advising growers to take preventive measures to ward off this menace.

For this, the farmers need to eradicate the alternative host plants, notably weeds like the Congress grass (parthenium). They are also required to destroy the colonies of ants during the land preparation operations as the ants help and abet in the survival of the pest. However, once the crop is in the field, constant monitoring is essential for early detection and destruction of the pests.

Indeed, the mealy bug hazard being what it is, one can only hope that the proposed campaign against it is implemented meticulously. Otherwise, this menace can get out of control, nullifying the gains from the cultivation of Bt-cotton.