Seasonal activity of spotted pod borer, Maruca vitrata (Fabricius) in relation to weather factors infesting cowpea

Abstract

A field experiment was conducted to study the seasonal incidence of spotted pod borer, Maruca vitrata in cowpea variety AVCP-1 at Entomology farm, B. A. College of Agriculture, AAU, Anand during Kharif, 2021. The incidence of M. vitrata in cowpea was commenced from 6th week after sowing i.e. 4th week of August (34th SMW) with 0.60 larva/plant and gradually increased to reached its first peak (3.51 larvae/plant) and the highest peak (6.97 larvae/plant) during the 1st week of September (36th SMW) and 2nd week of October (41st SMW) when crop age was 8th and 13th weeks old, respectively. Thereafter, the population gradually declined towards the crop maturity. Concerned to the damage of M. vitrata on pods of cowpea, it was recorded between 8.63 to 59.93% per plant. The maximum pod damage i.e. 59.93% per plant was observed in the second week of October (41st SMW) when M. vitrata incidence was at its highest peak. The population of M. vitrata had highly significant negative correlation with wind speed (-0.882**) whereas, bright sunshine hours (0.586*) and maximum temperature (0.625*) showed significant positive association on cowpea. Furthermore, it was worked out that the bright sunshine hours, maximum temperature and wind speed each contributed 11, 10.9 and 68.2% of the variation in the M. vitrata larval population, respectively.