Influence of weather parameters on incidence of cowpea pod borer in central zone of Kerala

Abstract

Cowpea is an annual herbaceous legume and is a main crop across Africa and Asia. It can be grown in sandy soil and is susceptible to low rainfall conditions. Cowpea pod borer (Muraca vitrata) is the main pest of cowpea. Weather factors affect different crops in many ways. Changing weather pattern over different regions affect host plants and pests. Total variability of pest populations in crops is determined by the natural growth of population and the influence of weather on activity and rate of multiplication of the insects (Kirk, 1997). Increased temperature increases productivity of cowpea if sufficient water is available, they also afford many insect species. Study conducted to examine the pest weather relationship of cowpea pod borer. Investigation was carried out on pod borer attack in cowpea [Vigna ungiculata (L.) Walp.] in five different stations of Thrissur, Kerala for three years from 2012-14. The study revealed that cowpea pod borer incidence had positive correlation with maximum temperature and diurnal temperature range, whereas, pod borer incidence showed a negative correlation with rainfall, number of rainy days and afternoon relative humidity. Step-wise regression analysis showed that maximum temperature and afternoon relative humidity experienced in prior week and rainfall and number of rainy days in prior two weeks are the significant weather factors for predicting pod borer infestation in cowpea.