Safety testing of pesticides for integration with trichogrammatids

Abstract

Trichogrammatids are being mass reared and released in different ecosystems for control of lepidopterous pests for the past seven decades in India. Indiscriminate use of pesticides often results in decline in the natural enemy population besides development of tolerance in the pests and their resurgence and secondary pest outbreaks. With intensification of agriculture, pesticide consumption has increased drastically from 1950-1951 to 1990-1991 and later decreased from 1991-1992 to 2000-2001 mainly due to integrated approach, environmental concerns, and introduction of newer molecules. Among the major groups of pesticides in India-insecticides are consumed more, followed by herbicides and fungicides. Cotton receives more quantity of the pesticides (52-55%) followed by paddy (17-18%) and horticultural crops (13-14%) as in 2001-2002. In the IPM program, chemical pesticides are integrated with biocontrol methods like release of egg parasitoids and biopesticides. Among 36 species of trichogrammatids described from India, only a few are being commercially mass reared and released. About ten such species have been tested for sensitivity to different pesticide groups. Those already tested include 4 in organochlorine group, 13 in organophosphates group, 12 in synthetic pyrethroid group, 32 in biopesticide group, and 21 in combination compounds for safety to biocontrol agents including trichogrammatids. Out of ten species screened for toxicity to various chemicals, T. chilonis has been more inten- sively screened against various pesticides by several researchers followed by T. japonicum and T. (= brasiliense) pretiosum. One of the main reasons for T. chilonis being the most widely screened against various pesticides and by various workers is due to its most dominant position in various ecosystems in India and its integration in IPM modules. In the future, studies should be oriented towards the safety of newly introduced pesticides, including combination compounds and biopesticides. Efforts should also be made to better understand the mechanism of populations building up tolerance, besides persistence by using different modern toxicological tools.