EVALUATION OF CERTAIN GENOTYPES AGAINST WHITEFLY (Bemisia tabaci GENNADIUS) AND ITS MANAGEMENT ON BLACKGRAM (Vigna mungo LINNAEUS)

Name of the Author : BODDEPALLI SRUJANA Title of the Thesis : EVALUATION OF CERTAIN GENOTYPES AGAINST WHITEFLY (Bemisia tabaci GENNADIUS) AND ITS MANAGEMENT ON BLACKGRAM (Vigna mungo LINNAEUS) Degree to which it is submitted : Master of Science in Agriculture Faculty : Agriculture Major field of study : ENTOMOLOGY Major Advisor : Dr. M. SESHA MAHALAKSHMI University : Acharya N.G. Ranga Agricultural University Year of Submission : 2014 The present study “Evalution of certain genotypes against whitefly (Bemisia tabaci Gennadius) and its management on blackgram (Vigna mungo Linnaeus) was carried out during rabi 2013 14 at Regional Agricultural Research Station, LAM, Guntur. Seasonal incidence of sucking pests i.e., both whiteflies and thrips was observed throughout the crop growing period in urdbean. Initially the incidence of whiteflies and thrips was observed from 15 DAS itself. The peak incidence of whiteflies was observed during 50 standard week (64 DAS) with a population of 2.1 whiteflies/ 3 leaves/ plant. Weather parameters together accounted for 60.66 per cent significant variation in whitefly population (R = 0.6066) and maximum and minimum temperatures, morning and evening relative humidities also could independently affect changes in whitefly population. The activity of thrips was observed from 46 standard week (12 to 18 November) till the end of the crop growth period. The peak incidence of thrips was observed during 49 standard week (56 DAS) with a population of 4.6 thrips/ 3 leaves/ plant. The multiple linear regression analysis revealed that the weather factors together were responsible for 47.64 per cent (R= 0.4764) of total variation in thrip population. Among the natural enemy complex, coccinellid beetles and spiders were predominant in blackgram ecosystem. The population of natural enemies was observed from initial stages itself with a peak abundance during 50 standard week (9 to 15 December) coinciding with peak activity of sucking pests. All the weather parameters and the sucking pests together exerted a very high and significant influence of 97.26 per cent on the population of natural enemies. Fifty one blackgram genotypes including one susceptible check were selected for screening against sucking pests (whiteflies and thrips) and replicated twice in a simple Randomized Block Design. The evaluation of different genotypes against sucking pests under field conditions revealed that the genotypes VBG-10-008, with less number of trichomes/ cm, less amount of total sugars and more amount of phenols was the least preferred entry whereas TPU-4 and TU-631 with more number of trichomes/ cm, more amount of total sugars and less amount of phenols were the most preferred entries by whiteflies. In case of thrips, KM-2293 and KUG-586 were the least preferred entries where as RUG-10 and RUG-44 were the most preferred entries. The genotypes with less number of trichomes, less amount of total sugars and more amount of phenols were observed to be less preferred by the sucking pests. Biochemical components viz., total sugars and phenols were found to be more in vegetative stage compared to reproductive stage. Among all the insecticides evaluated as foliar sprays, Spiromesifen 240 SC @ 0.096 per cent was found significantly superior in reducing the whitefly population followed by buprofezin 10 EC @ 0.01 per cent. Where as fipronil 5 SC @ 0.005 per cent was found highly effective against thrips followed by thiamethoxam 25 WG @ 0.005 per cent, with high reduction in population over control. Among the neonicotinoids tested, acetamiprid 20 SP @ 0.004 per cent and thiacloprid 21.7 SC @ 0.027 per cent were found promising against whiteflies with moderate efficacy, while thiamethoxam 25 WG @ 0.005 per cent and imidacloprid 200 SL @ 0.06 per cent proved better against thrips. The seed yield of blackgram was highest from spiromesifen 240 SC @ 0.096 per cent (1400 kg/ ha) followed by buprofezin 10 EC @ 0.01 per cent (1328.33 kg/ ha). However, both in terms of pest suppression and seed yield all the treatments were found significantly superior over the untreated control.