Influence of Weather Parameters on the Seasonal Abundance of Legume Pod Borer Maruca vitrata (Crambidae: Lepidoptera) on Dolichos Bean (Lablab purpureus var. typicus)

Abstract

Background: Legume pod borer, Maruca vitrata (Fabricius), infests the Dolichos bean throughout the cropping season. However, there is no information on the seasonal abundance of M. vitrata over different seasons on Dolichos bean, which is an essential tool for forecasting and developing integrated pest management strategies. Methods: The seasonal abundance of M. vitrata on Dolichos bean were studied during three consecutive cropping seasons of 2019 Summer, Kharif and Rabi. The larval population in flowers and pods and the number of larval webbings and weather parameters were recorded and subjected to correlation and multiple linear regression analysis. Result: The overall larval abundance was observed to be higher in flowers than in pods. The highest larval abundance in flowers and pods was 14.60 and 13.40 during the 48th and 50th standard meteorological week (SMW) of Rabi 2019 respectively, which corresponds to 8 to 10 weeks after sowing (WAS) in flowers and 10 to 12 WAS in the case of pods. The number of larval webbings was higher, with 18.76 during the 49th SMW of Rabi 2019. The maximum temperature had a significant negative correlation with the larval abundance in flowers (r= -0.570), pods (r= -0.523) and the number of active webbings (r= -0.477). At the same time, the regression coefficient shows that rainfall had a significant negative influence on the larval abundance in pods (B= -1.26).