Seasonal incidence of insect-pests of blackgram,Vigna mungo(Linn.) and its correlation with abiotic factors

Abstract

Biotic and abiotic factors limit the productivity of blackgram including insect pests like leafhopper, Empoasca kerri , whitefly, Bemisia tabaci , tobacco caterpillar, Spodoptera litura , semilooper, Trichoplusia ni and bihar hairy caterpillar, Spilosoma obliqua . The high population of 3.49 whiteflies/leaf was observed during 39 th standard week. Whitefly and leafhopper population with sunshine hours showed non-significant negative correlation while rainfall, temperature (minimum and maximum), relative humidity (morning and evening), and wind velocity showed a non significant positive correlation. The highest population of tobacco caterpillar, 3.83 larvae/m 2 was recorded during 40 th SW. Rainfall and wind velocity showed non-significant negative correlation while temperature (minimum and maximum), relative humidity (morning and evening) and sunshine showed a non-significant positive correlation with the population of S. litura . Maximum level of T. ni population 8.37 larvae/m 2 attained during 39 th SW. Population of T. ni had significant positive correlation with minimum temperature and evening relative humidity. The highest population of S. obliqua , 29.50 larvae/m 2 was recorded during 40 th SW. Rainfall and wind velocity with S. obliqua population showed significant negative correlation. Maximum level of coccinellids 2.36/m 2 was recorded during 39 th SW. Rainfall, wind velocity and sunshine showed non-significant negative correlation while temperature (minimum and maximum) and relative humidity (morning and evening) showed non-significant positive correlation.