Seasonal incidence of major insect-pests of pigeonpea and management of pigeonpea pod fly, Melanagromyza obtusa Malloch
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Date
2020-10-19
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ANDUAT,Kumaragnaj, ayodhya
Abstract
The present investigation entitled “Seasonal incidence of major insect-pests of pigeonpea and management of pigeonpea pod fly Melanagromyza obtusa Malloch” were carried out for two consecutive crop seasons i.e., Kharif, 2018-19 and 2019-20. Maximum larval population of Helicoverpa armigera was observed in 12th (7 .36 larvae / 5 plants) and 11th (9.20 larvae / 5 plants) standard week whereas it was minimum in 47th (0.20 larvae / 5 plants) and 1st (0.12 larvae / 5 plants) standard week, respectively whereas highest population of Exelastis atomosa was observed in 11th and 10th SW and lowest population was observed in 6th & 15th and 4th SW, respectively during both the year. Clavigralla gibbosa population attained the peak during 7th and 8th SW and minimum population was observed during 16th and 2nd & 16th SW and the peak larval population of Lampides boeticus was recorded in 10th SW during both the years. The lowest population was observed in 14th and 15th SW during 2018-19 and 2019-20, respectively. The peak period of occurrence of M. obtusa maggot and pupae was observed in 9th & 12th SW and 11th & 12th SW during both the year, respectively. The correlation coefficients between the incidence of Helicoverpa armigera, Exelastis atomosa, Clavigralla gibbosa, Lampides boeticus and maggot of M. obtusa with abiotic factors showed both positive as well as negative relationships at non significant level during both the years. The correlation coefficients between the pupae of M. obtusa and weather factors had significant positive correlation with minimum temperature (0.621* & 0.716*), maximum temperature (0.588* & 0.516*) and sunshine hour (0.600* & 0.561*) while relative humidity showed significant negative correlation (-0.681* & -0.646*) and rainfall had non significant negative correlation in both the years, respectively. During Kharif, 2018-19 the Torymoides spp. and Ormyrus orientalis spp. was recovered for the first time from the pods collected on second fortnight of February and the level of parasitization was 14.28 per cent. The parasitization increased on first fortnight of March and reached to its maximum level 25.71 per cent. During Kharif, 2019-20, the maximum parasitization on first fortnight of March and reached to its maximum level 25.00 per cent. Out of 30 germplasm of pigeonpea evaluated against Melanagromyza obtuse, only three germplasms viz. ICP 8863A, ICP 6443 and JBT 46-61 were found moderate resistant against pigeonpea pod fly. None of the germplasm fell under highly resistant category during both the years of study. All the treatments were significantly superior over the control when observations on per cent pod damage were taken at 3, 7, 10 and 14 days after treatment. Chlorantraniliprole 18.5 SC @ 30 g a.i./ha was found best in reducing pod damage caused by Melanagromyza obtuse. Emamectin benzoate 5 SG @ 11 g a.i./ha was the second best treatment in both the year. The maximum cost benefit ratio of 1:14.56 was obtained from the plots treated with Chlorantraniliprole 18.5 SC @ 30 g a.i./ha followed by Emamectin benzoate 5 SG @11 g a.i. /ha (1:13.62). The minimum (C:B) ratio of (1: 5.81) was obtained Imidacloprid 17.8 SL @ 20 g a.i./ha treated plots.
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