Asian Research Thesis Index

Abstract

In this study, factors regarding the excessive use of pesticides and those particularly involved in the cultivation of high input and low input rice crop were investigated. Farmers’ sources of Basmati rice seed acquisition and perception of pest insects’ incidence and their management practices in rice crop were also evaluated. Results indicated that the main reason for farmers’ adoption of high input rice farming was to get better yields and profit. The main sources of rice seed acquisition were the home retained, local market and seed companies. Farmers were well aware of major pest insects of rice and reported moderate incidence of rice stem borers and high incidence of rice leaffolder but little was known about natural enemies and diseases. The most common reason for excessive use of insecticides was the misconception that pesticides were necessary to increase the yield. Farmers still relied to a great extent on chemicals to control the pests in rice crop and majority of them ignored economic threshold levels (ETL) recommended for the control. But the effective and economic suppression of insect pests in rice ecosystem by the judicial use of pesticides on the basis of ETL is utmost essential. Therefore, ETLs for the chemical control of rice stem borers (Scirpophaga incertulus Wlk. & S. innotata Wlk.) and rice leaffolder (Cnaphalocrosis medinalis Gn.) in the traditional Basmati rice growing area, the Kallar tract were also determined to be 5% dead-hearts (DH) and 3% folded leaves for stem borers and rice leaffolder respectively. The use of insecticides ignoring recommended ETLs along with higher doses of fertilizers is not only the cause of economic losses but also harmful to the insect biodiversity. So the effect of high inputs (HIP) farming practices on insect communities was also investigated. The higher number of species richness and abundance were measured for low input (LIP) systems. On the other hand some insects were abundant in HIP systems because of their adaptation to such kind of habitat. The insect species richness and abundance increased with rice crop age and showed close relationship with crop. All the major trophic guilds, except non rice pest (NRP), were also in abundance for LIP systems. Some species of insect were found sensitive to agrochemical pollution and were regarded as bioindicators. The higher Shannon’s value in some cases for HIP farms suggested that agrochemicals had a significant impact in eliminating the rare species and hence increased the Shannon’s and evenness values among the species. The overall effect of HIP rice farming on insect species richness and abundance was significantly negative. The LIP systems were found having greater diversity along with supporting a good number of rare species.

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