Seasonal Incidence of Major Insect Pests on Early Maturing Pigeonpea [Cajanus cajan (L.) Millsp.] in Relation to Abiotic Factors of Varanasi Region of Indo-Gangetic Plain

Aim: To study the seasonal incidence pattern of major insect pests on two commonly grown cultivars of pigeonpea.

Study Design: Complete Randomized Block Design.

Place and Duration of Study: Field experiments were conducted at Agriculture Research Farm, Institute of Agricultural Sciences, Banaras Hindu University, Varanasi during kharif seasons of 2015 and 2016.

Methodology: The pigeonpea crops (cultivars ICPL 87 and UPAS 120) were grown in plots of 10 m X 5 m (50 m2) replicated thrice and the crop fields were kept free from pesticide sprays. Five plants were selected randomly from each plot, and weekly observations of the respective pests were taken through Plant Inspection Method (PIM) starting from 50 per cent flowering stage till maturity of the crop and then correlated with the meteorological data.

Results: The peak infestation by the pod pest borer complex was recorded during the second fortnight of October (44th and 45th standard week) of both the years. Correlation studies indicated that the population of these insect pests (Tur pod bug (C. gibbosa), Legume pod borer (M. vitrata), Tur pod fly (M. obtusa), Legume pod borer (M. vitrata) exhibited a significant positive correlation with maximum and minimum temperature whereas a significant negative correlation was established with relative humidity and rainfall. The multiple regression analysis revealed that variations of different weather variables caused approximately more than 80 per cent variations in the populations of these insect pests in both the cultivars during both years, respectively.

Conclusion: The information on seasonal activity and population dynamics of legume pod borer, tur pod fly and tur pod bug on pigeonpea generated to give an indication about the importance of the different weather parameters in developing weather based forecasting models for successful development and implementation of the pest management strategies against these insect pests of pigeonpea.