Vol. 10, Special Issue 3 (2021)

Author(s):
Shanti Kurly and PK Singh

Abstract:
The field experiment was conducted in research farm BAU, Kanke, Ranchi during Kharif 2016 and 2017 for assessment of seasonal incidence of defoliators on black gram with relation to weather factors. The population of defoliators recorded namely, tobacco caterpillar (Spodoptera litura), Bihar hairy caterpillar (Spilosoma obliqua), semilooper (Trichoplusia ni) and grasshoppers (Khaoyaiana nitens, Atractomorpha crenulata and Diabolocatantops pinguis). The peak population of defoliators (tobacco caterpillar, Bihar hairy caterpillar and green semilooper) was recorded during the second and third week of August (32nd and 33rd standard meteorological week) while the highest population of grasshopper recorded in the third and fourth week of August (33rd and 34th standard meteorological week). The temperature and relative humidity positively impact on defoliator population, hence the correlation of defoliators positively significant with temperature and relative humidity. The rainfall correlated negatively with defoliators. The multiple linear regressions analysis revealed that per cent abundance population of defoliators were recorded as follows tobacco caterpillar (50.4 and 75.8), Bihar hairy caterpillar (44.6 and 68.9), green semilooper (50.5 and 84.4) and grasshopper (44.4 and 74.7) during the year 2016 and 2017 respectively.