Ecological pest management for emerging pest problems
Since the beginning of agriculture, around 12 000 years ago, humans have been struggling to reduce the adverse effects of pests on crop production and storage. The development of synthetic pesticides revolutionised pest management in agriculture.
However, ecological and human health risks, together with the economic costs of heavy reliance on chemical pesticides have become more apparent. In this context, it is relevant to recall Julian Huxley’s lines in his preface to Rachel Carson’s revolutionary book, “Silent Spring”: “Pest control is of course necessary and desirable, but it is an ecological matter, and cannot be handed over entirely to the chemists”.
Meghalaya, a small state in the North Eastern region of India, is inhabited by different indigenous communities, mainly of Mongoloid origin. Of the approximately 2.3 million population, about 85 percent live in rural areas and depend on agriculture for their livelihood. Due to physiographic features, shifting cultivation and Bun cultivation (raised beds on slopes) have been the predominant forms of agriculture. Traditional fallow periods of 20 - 30 years have now reduced to 3 - 5 years, mainly due to pressure from increasing populations. In response to this, the state government introduced the settled form of agriculture called wet rice cultivation during the 1980s. Farmers were encouraged to use high yielding varieties and subsidised agrochemicals. This led to a dramatic increase in the total cropped area in the state: an increase of about 42 percent during the last twenty-five years.
The emerging pest problems
Many studies indicate that fewer pest problems are experienced in shifting cultivation due to its inherent management practices, such as mixed cropping, fallowing and rotation. In contrast, continuous monocropping in settled cultivation is reported to contribute to the build-up of pests and diseases. The introduction of wet rice cultivation in Meghalaya has also brought new pests to the area. The Indian Council of Agricultural Research for North Eastern Hill Region, while studying the pests in upland agriculture, found that paddy grown in shifting cultivation fields are almost free from insect pests, while those grown in semi-terraced lands had moderate incidences of the gundhi bug (Leptocorisa oratorius). On the contrary, crops grown in terraces were found to be attacked by a number of pests in addition to the gundhi bug, like stemborers, the rice hispa, rice caseworms, leaf folders and hoppers. Farmers say that the terrace cultivations initially provided good harvests. However, infestation of paddy by different types of pests previously unseen, soon became a major cause of concern.
Box 1. Planting of fruiting trees in and around crop fields to attract predatory birds
Farmers of the West Garo Hills plant fruit bearing plants like Bridelia retusa, Dendrophthoe falcata, Morus macroura and Sapium baccatum in terraces, sometimes in home gardens and jhum fields. These plants attract predatory birds by providing shelter and food. The birds eventually keep pest populations down by feeding on the different kinds of insect pests, mainly larvae, caterpillars and nymphs.
Though no-one can identify who started this method, the farmers unanimously agree that its development is linked with the traditional activity of hunting. A long time ago, while hunting in the forest, farmers noticed that some birds prefer particular plants, and that these birds were also seen to feed on caterpillars as well as small insects. Those farmers tried planting these plants near the crop fields, to see whether the birds would feed on the insect pests. These methods are now commonly practised. The farmers’ philosophy about this method is simple: “We arrange food and shelter for the birds, in return they take care of our pests”
The extension and support delivery systems in the state are comparatively weak. This is probably due to poor infrastructure and the lack of extension personnel willing to work in remote, harsh areas. Even where such services are available, the upland people often cannot afford to use these services. Traditionally, farming was done for subsistence rather than for commercial benefit, and the farming system was self-sustainable with zero external inputs. Though the newly introduced settled cultivation is also mostly carried out for subsistence only, it depends on costly and inaccessible external inputs, making it much less sustainable. This is a matter of serious concern among those farmers who have adopted wet rice cultivation on a larger scale, as their long-term survival is at stake.
Participatory research was carried out to document and assess the traditional pest management practices followed by the three dominant tribes of the state: Khasi, Jaintia and Garo, inhabiting the West Khasi Hills, Jaintia Hills and West Garo Hills respectively, and to assist them in sustainable food grain production in an ecofriendly manner. The study was started in 2002 through the IFAD-funded North Eastern Region Community Resource Management Project for Upland Areas, and is still ongoing through other small grant projects.
The innovative nature of indigenous communities can be seen among the farmers of Meghalaya, and is evident from the array of pest management methods they have developed to control different kinds of pests which came along with the newly introduced settled wet terrace paddy farming. Most of these methods were developed and are being developed based on locally available resources. The methods are environmentally friendly because chemical pesticides are not used, and most importantly, because they have strong foundations in wellestablished biological and ecological principles.
Photo: Sangita Roy
For instance, the use of fruit bearing trees to attract predatory birds (Box 1) by the Garos of the West Garo Hills district is a clear demonstration of sustainable biological control of pests. Unlike the conventional biological control methods in which the introduced predator or parasite itself may become a problem, the sustainability of the traditional method appears to be high, as it uses local plants to attract local predators. Such methods further reflect the community’s understanding of food web linkages and population interactions. They harness the help of predators to remove the pests - a basic ecological principle of population control that operates in a natural ecosystem. Another important ecological principle implicit in this method is the conservation of flora and birds, even though it is not perceived by the farmers. Rats are also controlled by employing the same principle. Branches, preferably of bamboo, are put in terraces. They act as a resting place for owls at night, which will keep the rat population in check.
The Khasis of West Khasi Hills practice another interesting method, and use cow’s blood to repel birds from paddy fields. A small bird species, locally known as phreit, comes in flocks and damages the paddy, breaking the tillers. Usually it destroys the crop during the maturation period. To stop this, farmers put fresh cow’s blood in a bamboo pipe. The pipe is tied with a stick and is placed in the paddy fields. According to the farmers, after 2 or 3 days the blood starts to emit a smelly gaseous substance, which acts as repellent to the birds. This practice also suggests an understanding and exploitation of the principle of animal behaviour, as it seems to mimic situations where alarm behaviour of the birds is used to prevent crop damage.
Perhaps the most widely-used of all the traditional pest management practices is the use of decomposing crabs to control rice bugs (as the filling of paddy grain starts, locally available crabs are smashed and put on pointed bamboo sticks in terraced paddy fields). This is practised throughout the entire state by all communities. An in-depth study of the practice suggests that it is an exploitation of the principle of food preference. This practice is environmentally friendly, as some farmers replace the crab baits as soon as they dry up, which otherwise may lead to elimination of the bug species from the natural ecosystem - not desirable from a conservation point of view. It also conserves water, as collecting the crabs lessens the loss of water through crab holes. Though other small animals like snails or frogs can also be used to attract the bugs, crabs are believed to be more effective. On-farm trials of the method revealed that by using a crab of 2.5 x 3 cm size as bait, 80 - 85 bugs can be trapped per 5 m2 in five days. Impressed by the effectiveness of the method, the state government has recommended its inclusion in the formal plant protection package. They are promoting a modified trap through agricultural bulletins, and at farmer trainings. The modified technique has been incorporated in the IPM recommendations for rice bugs, and is being successfully implemented in the entire state. Though there are no figures about how many farmers have adopted the customised trap, many farmers simply use the crabs in the traditional way. In all, the whole farming community can benefit from the renewed interest in age-old traditional methods.
The way ahead
The above descriptions are just a few of the hundreds of traditional ecofriendly pest management practices developed by the traditional farmers of Meghalaya in response to the pest problems emerging from the newly introduced wet terrace cultivations. The uniqueness of these practices is their suitability to the local conditions; they are inexpensive and easy to implement. The farmers state that when they use these methods in combination, they can be very effective. As different practices are used for the same purpose (pest) at the same time, one practice complements another, resulting in less pest damage to the crops. To be recommended for wide-scale use, however, these traditional practices need further evidence and modification. Nevertheless, integration of the authenticated traditional methods and their wider applicability may ensure a more sustainable and higher return from the fields - a step towards the reduction of rural poverty and hunger. Lastly, if the pest problems are taken care of, wet rice cultivation may prove to be a good alternative form of cultivation for the traditional farmers of Meghalaya in particular, and shifting cultivation areas in general.
Text: Bikramjit Sinha, Randhir Singha and Dhrupad Choudhury
Bikramjit Sinha. Young Scientist (DST), G. B. Pant Institute of Himalayan Environment and Development, North East Unit, Vivek Vihar, Itanagar - 791113, Arunachal Pradesh, India. E-mail: firstname.lastname@example.org
Randhir Singha. Executive Director, Resources Centre for Sustainable Development, RCSD 20, Bye lane 12 (west), Rajgarh Road, Guwahati-781007, Assam, India. E-mail: email@example.com
Dhrupad Choudhury. Programme Coordinator, IFAD/ICIMOD Grant Programme, International Centre for Integrated Mountain Development. P.O. Box 3226, Kathmandu, Nepal. E-mail: firstname.lastname@example.org
- Pathak, K.A., N.S.A. Thakur, K.R. Rao and A.N. Shylesha, 2001. Insect pests of crops and their management. In: Verma, N.D. and B.P. Bhatt (eds.) Steps towards modernisation of agriculture in NEH Region. ICAR Research Complex for NEH Region, Umiam, Meghalaya, India.
- Sinha, B. 2007. Evaluation of indigenous insect pest management practices among certain ethnic upland communities of northeast India. Ph. D. Thesis, Gauhati University, Guwahati, Assam, India.
- Thurston, H.D. 2001. Pest management in shifting cultivation systems. In: IFAD, IDRC, CIIFAD, ICRAF and IIRR, Shifting cultivation: Towards sustainability and resource conservation in Asia. International Institute of Rural Reconstruction, the Philippines.