Diversity, Bio-ecology and population dynamics of insect pests of pigeon pea in eastern India

Abstract Field and laboratory experiments were conducted at Bidhan Chandra Krishi Viswavidyalaya (BCKV) to assess the diversity, bio-ecology and impact of weather variables on population dynamics of insect pests in pigeon pea during kharif season of 2016-2018. The results revealed that a total of 65 insect pest species were recorded in pigeon pea in the eastern India. Among them, 8, 30 and 27 numbers of species were classified as major, minor and negligible pests. Diversity study showed minimum variability between the two years. The average duration of life cycle of Helicoverpa armigera, Melanagromyza obtusa, Exelastis atomosa and Maruca vitrata were recorded at 43.16±0.74, 26.25±0.58, 36.5 ± 1.25 and 28.0 ± 1.50 days under relative humidity and temperature regime of 75 ± 2% and 28 ± 2°C, respectively. The population dynamics showed that H. armigera, M. vitrata, M. obtusa, E. atomosa and A. clavipes reached their peak during 8th standard meteorological week (SMW), 52nd SMW, 8th SMW, 7th SMW and 4th SMW with 1.40-1.66 larvae/plants, 14.73-15.60 larvae/plant, 208.33-212.33 maggot and pupae/plant, 9.73-10.53 larvae/plant and 43.00-47.0 grubs/plant during 2016-17 and 2017-18, respectively. The correlation analysis revealed that temperature (maximum and minimum) showed positive influence on larval population of H. armigera, M. obtusa, E. atomosa and A. clavipes whereas, maximum and minimum relative humidity and rainfall impacted negatively during both the years. In case of M. vitrata, maximum and minimum temperature demonstrated significant negative correlation, whereas maximum and minimum relative humidity showed positive and significant correlation during both the years. Whereas, rainfall showed non-significant negative correlation on pest population of all the pod borers of pigeon pea.