Resisting change or taking up the challenge?

Resistance of insect pests, as a result of heavy insecticide use over many years, is a growing problem worldwide. The seriousness of the problem, along with resistance in weeds and fungi, were highlighted at the fourth annual conference dedicated to the subject "Resistance 2001: Meeting the challenge" held at the UK crop research station, IACR Rothamsted. Delegates included researchers from around the world and representatives of agro-chemical companies, such as Monsanto and Syngenta. During the three days of the conference the mechanisms, risk assessment and management of resistance were discussed along with the population biology and genetics of insect pests. All those who attended were interested in discovering more about resistance, and case studies were presented and questions for the future were raised. But what about the message to developing countries, to the small-scale farmer who continues to use greater amounts of chemicals each year? And, at the end of the day, whose responsibility is the issue of resistance - the farmers who use the chemicals or the agro-chemical companies who produce them?

credit: Derek Russell, NRI

credit: Derek Russell, NRI

India is the fourth largest cotton producer in the world with some 60 million people deriving income from cotton production. Despite forecasts that demand would continue to rise, in recent years Indian production has stagnated at 1.2 - 1.3 million bales. A major factor in production shortfalls in most seasons is the impact of insecticide resistant cotton pests: annual losses due to Helicoverpa armigera alone on cotton and legume crops in India are estimated at US$300 million. And, as several of the major pests of cotton have developed resistance to many of the available insecticides, increasing use of pesticides only serves to exacerbate resistance problems.

Across Asia, 40% of the cost of growing cotton is insecticides. Farmers are aware that this is a major and even an escalating cost and, although larger quantities may have to be used each year, if control of pests can still be achieved then the issue of resistance is generally not considered. Precise input costs are usually not recorded, so the important issue to many small-scale farmers is not profit but their overall yield. An important aspect of any pest management practice therefore is to focus on at least maintaining yields, or even enhancing them. This can present a challenge when preventative measures for resistance are usually based on promoting a reduction in insecticide applications; even where the cost of chemicals has decreased farmers fail to realize the connection if all they can 'see' is less crop at the end of the season. However, farmers do appreciate that the cost of 'older' chemicals is less than more recently developed insecticides. Thus they can be persuaded that if a chemical is no longer effective and a cheap alternative is not available, then using it in a different way or mixing it with another chemical may be a viable option.

Building on previous DFID-funded research, a group of UK and Indian scientists* (see below), working with farmers, has developed and tested methods which have reduced the need for insecticides. Following this model, farmers target limited sprays of recommended insecticides on pests only when absolutely necessary. All chemicals suggested for use are known by local trade names and are available in the quantities required from village shops. The results of trials in three states have been dramatic. In Maharashtra, for instance, use of pesticides has been reduced by 95% whilst yields have increased by a substantial 70%. Yield increases in Tamil Nadu and Andhra Pradesh have not been as great (17 and 25% respectively) because pest numbers have been higher in recent years, but pesticide usage has still been reduced by over 40%. When the model was introduced to the Punjab, encouraging results were also achieved.

Although this DFID-funded project has come to an end, the Indian Government is now promoting adoption of these practices in 500 villages in the 20 major cotton districts. These regions currently account for 80% of the total insecticides used on cotton in India, so there is great potential for overall pesticide use in cotton to be considerably reduced. And, despite the fall in sales, perhaps surprisingly even traders have been very supportive of the measures since, with the resistance management methods increasing both yields and profits, farmers have more money and are less likely to default on credit.

The majority of small-scale cotton farmers support their families on less than two hectares of land and the cotton crop provides the only source of income for food, medicines and education. With the uptake of resistance management in cotton, decreased use of pesticides has led to reduced hazards to environment and human health, greater cotton yields and larger profits for the hundreds of poor rural families which are dependent on the crop. Not least there has also been a significant change in resistance to the most heavily used insecticides, making them more effective against the pests again. Resistance may not be a priority for small rural farmers but when the added benefits of resistance management in terms of yield and profits can be demonstrated, along with consistent control of pests, farmers are willing to take steps to meet the challenge of resistance.

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