Neem based Integrated Approaches for the Management of Tea Thrips Scirtothrips dorsalis Hood (Thripidae: Thysanoptera) in Tea

Abstract

Tea thrips, Scirtothrips dorsalis Hood (Thripidae: Thysanoptera), has been the most destructive pest of tea in North East India since last few decades. In order to reduce the load of the synthetic chemicals in tea vis-a-vis their deleterious effect, integration of biopesticides, synthetic pesticides along with effective spraying strategies, have been attempted. The anti-insect property of “neem”, Azadirachta indica A. Juss. (Meliaceae) has been used to solve many pest problems. Two field trials were conducted between May and June 2008 at Red Bank Tea Estate, Jalpaiguri, West Bengal, India following randomized block design against tea thrips, S. dorsalis. In one experiment, different azadirachtin concentrations (300, 1,500, 3,000, 10,000 and 50,000 ppm) at different doses (1:200, 1:300, 1:500, 1:1,000 and 1:1,500) were evaluated to find out the relationship between azadirachtin concentration and its bioactivity against S. dorsalis. At 50,000 ppm azadirachtin concentration 82% control of reduction in thrips population could be attained, whereas at 3,000 and 10,000 ppm, gave 60–73% reduction and 300 and 1,500 ppm <60% control was possible. Therefore, azadirachtin concentration and its dilutions are the major criteria to determine the bioactivity against tea thrips. In another field experiment, a neem formulation alone and in combination with Tea Research Association recommended and reduced dose of endosulfan and monocrotophos were tested. Treatments with combined formulations (neem + insecticide) recorded significant reduction in S. dorsalis incidence even at reduced doses (1:600 and 1:800), as compared to sole application of neem or synthetic insecticide at recommended doses. Azadirachtin concentrations and their bioactivity, effective combinations and dose of the insecticides along with their formulations in controlling S. dorsalis have been presented and discussed.