Population Build Up And Biopesticides Against Pod Borer Helicoverpa Armigera Hub. Infesting Chickpea
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Date
2001
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Birsa Agricultural University, Ranchi
Abstract
Investigation were carried out during rabi 1999-2000 in the pulses area of Birsa Agriculture University ,Ranchi to study the population build up and management of Helicoverpa armigera (HUB) infesting chickpea under the agro climatic conditions prevailing around Ranchi.
Initally low populations of H. armigera were recorded during second fortnight of January 2000 on chickpea snow in different ways. During 1st week of February, the population of the pest was increased in all the sowing dates which continued for two consecutive weeks and increased abruptly forming the highest peaks on 21st February in all the sowings. The peaks of the larval populations were occurred under the influence of minimum and maximum temperatures of about 10.3oC and 22.6C, respectively, evening relative humidity ranging from 48 to 55 percent coupled with rainfall of about 15.4,43.2, 10.4 and 3.6 mm received during 3rd ,6th ,7th and 8th standard week i.e. during the month of January and February. Cloudy weather condition of about 6,2,4 days during 6th ,7th, 8th standard weeks respectively and lower rate of parasitization also favored the peak of the population .Falling phase of the pest populations were negatively and significantly correlated with temperatures.
Early sowing of chickpea (21st and 31st sowing) received lower incidence of H.armigera as well as higher grain yield of chickpea as compared to late sowing viz. 30th November ,10th,20th,and 30th December sowings.
Multiple regression between pod damage and yield of chickpea sown on different dates indicated that a unit increase in pod borer damage was followed by a decline of 12.40 Kg/ ha in yield.
Biopesticides like Bt, Halt, Dipel, Biolep. NSKE, NPV, Delfin, cartap hydrochloride, Rakshak gold and Rakshak were responsible for higher larval reduction ranging from 84.96 to 90.98 percent, 14 days after treatment. Endosulfan used as check was responsible for reducing the population to the extent of 92.23 percent. Lower pod damage and higher grain yields were also obtained by the application of biopesticides which were comparable with endosulfan. So far newer insecticides are conceded deltamethrin + triazophkos (Spark 36EC), lambdacyhalothrin (Karate 5EC) lufenuron (Match 5%EC) and acephate fenvalerate (Koranda) were found to be very effective in reducing the larval population to the extent of 95.19 percent, 14 days after treatment, Cypermethrin remained at par with newer insectivides. The performance of NPV and Achook were as good as cypermethrin.