Prior to the introduction of conventional chemical pesticides, paddy farmers in Sri Lanka used a wide range of traditional pest control practices. These practices are rapidly disappearing as farmers adopt high yielding varieties (HYV) of rice which necessitate chemical use. I conducted a study with 30 farmers from the Badulla and Hambantota Districts.
The farmers’ practices can be categorized as biological, botanical, or mechanical methods. In addition, some practices are supplemented with religious ceremonies and rituals.
In and around their fields farmers maintain habitats and develop micro-climates required for the vertebrates, reptiles, birds, and mammals that prey on crop pests. The farmers I interviewed described some religious rituals which, upon close scrutiny, appear to help in attracting a number of crop pest predators.
For example, Ptyas mucosus, commonly known as the rat snake, and the lizard, Varanus salvator, feed on rats and a number of other small mammalian and crustacean paddy pests.
The paddy farmers portrayed a facile knowledge of the botanical species in their environment and identified a wide range of plants that they had used for pest control. Diospyros affinin (kaluwel), Anamirta cocculus (Tithtwel) and Ananas comosus (pineapple ) are believed to control flies such as Orceolia oryzae (Gap Massa) and Atherigona oryzae (kanda Massa) Euphorbia (Daluk) is used by farmers to control Tryporyza incertulu (puruk panuwa).
The leaves of these plants are crushed and added at the point of impounding water (water body) for irrigating rest of the paddy. The seeds of Garyota urens (kitul) are crushed and added to water at the field entry point to destory paddy damaging worms.
The leaves of pongamia pinnata (karadha) and Crotolaria retusa (keppitiya) are added to paddy soil to control rice pests. Cycas circinalis (Madu) Cymbopogon citratus are planted and hung around paddies; farmers believed these plants emitted odours that repels certain rice pests.
Again, to control rats, pieces of raw Garica papaya are spread in paddies. The farmers believe papaya has a chemical substance, causing tissue damage in rats mouths. Farmers world over, use wood ash, but those interviewed found Cymbopogon nardus plants particularly effective in controlling Spodoptera mauritia (Godawella)
Food and oil lamp traps are the major means of mechanical pest control in addition to other cultural practices such as soil cultivation. Regardless of the methods used, integrating newly introduced technology with indigenous strategies of pest control may in fact, increase the effectiveness of both approaches.
For example, a recent experiment carried out in India concluded that the use of white lights bulbs provided an effective element for pest traps (Widanapathirana, 1983).
“The unfortunate conclusion of this study is one that has been found the world over: the farmers’ knowledge developed through the ages and handed down through generations, is disappearing and is being replaced by what younger agriculturalists call "modern scientific knowledge" We must reverse this trend,” says Prof Anil Gupta, Vice Chairperson, National Innovation Foundation, Ahmedabad.