Executive Summary : | Rice is one of the predominant cereal crops cultivated across the country. This crop forms the basis of livelihood for majority of the farmers as well as got export significance. Damaged caused by insect pests is one of the limiting factors affecting the successful production of rice. Brown Plant Hopper (BPH) is one of the major insect pests infesting crop and causing significant economic yield loss. The present management practices and even the novel insecticide molecules were not up to the mark in limiting the BPH menace. India is a diverse country with varying climatic zones and is capable of hosting many species of Insects and rice is cultivated in various agro-climatic zones. Insect populations harbored in such varying climate and habitat response differentially to different selection pressure caused by biotic and a biotic stress including the application of insecticides. This differential response is caused by various factors and the existence of genetic variation in between and within population plays major role. Considering all these issues, the major aims of the present study is to determine the resistance status in Nilaparvata lugens major rice growing regions in India and to quantify the extent of genetic variation if any in different field population of N. lugens. The last and important aim of the study is to assess the activity of metabolic enzymes involved in detoxification of insecticides in N. lugens. Survey will be conducted to collect the populations from the major Rice growing regions across the North, Central and South zones. These collected field populations would be subjected to bioassays against the various insecticides viz., Thiamethoxam, Dinotefuran, Buprofezin and Pymetrozine and same population would also be used for genetic diversity analysis for quantifying extent of genetic variations in field populations using MtCOI gene. Once the median lethal concentration dosages (LD50) are estimated, these will be compared with media lethal dosages of susceptible laboratory populations. Based on these two parameters, the resistance ratios will be calculated and status will be interpreted. As a confirmatory test, the populations will also be subjected to enzyme assays, for analyzing activity of insecticide detoxifying enzymes in the population. All these parameters were interpreted accordingly and a clear picture of resistance with biochemical basis can be concluded. The genetic diversity of provided us with the haplotype composition within the zones and their respective resistance status. Mapping and correlating all these will help in formulating need based and precise management practices that are region specific. The data generated through this study would also help as reference standard for the future studies and can be used to evaluate different aspects like effectiveness of resistance management strategies, novel insecticides evaluation, status of the pest etc. |