Introduction

Abstract

Biomagnification through food chain and other side-effects from the intensive use of persistent chlorinated hydrocarbon pesticides¹ have necessitated their replacement by carbamate and organophosphorus pesticides in most developed countries. In tropical developing countries organochlorine pesticides are still widely used for reasons of low cost, ready availability, and indigenous capability to produce these pesticides. However, because of the increasing concern over their effect on the environment, efforts are made even in developing countries to use carbamate and organophosphorus pesticides as a replacement for organochlorines. Moreover, carbamate and organophosphorus pesticides are increasingly recommended for the control of specific pests not controlled by organochlorines. For instance, the brown planthopper (Nilaparvata lugens Stål.) is a major pest of rice in the tropics and sub-tropics and carbamates such as carbaryl, carbofuran, and 2-isopropylphenyl N-methylcarbamate (MIPC) have been increasingly used as the most effective insecticides against this pest. Admittedly, until the mid-1960s no carbamate pesticides were used in India and possibly other developing countries.