Population dynamics of pink stem borer, Sesamia inferens (Walker) on maize as influenced by weather conditions

Abstract

A field study on population dynamics of pink stem borer, Sesamia inferens (Walker) on maize was carried out during rabi, 2015-2016 at the research farm of CCS Haryana Agricultural University, Regional Research Station, Karnal. Studies on population dynamics revealed that the maximum number of egg masses was observed during 46th SW (standard week), 2015. The larval population increased after 45th SW and reached the maximum during the 49th SW, 2015 and then declined till 7th SW, 2016. Maximum plant infestation by larvae was recorded 19.5 per cent in inbred HKI 1128 and 21.0 per cent in hybrid HQPM 1 during the 7th SW, 2016. No larval activity of S. inferens, plant infestation and dead hearts were observed during 2nd SW to 4th SW of 2016 (second week to last week of January). It could be due to the fact that insect might have entered the hibernation. Correlation of S. inferens population with various environmental factors revealed that larval population had a significant negative correlation with maxi-mum temperature (Tmax.) and minimum temperature (Tmin.), rainfall (RF) (r= -0.4992, -0.5183 and -0.5698) on HKI 1128 and (r= -0.4872, -0.4717 and -0.5242) on HQPM 1, respectively. Multiple regression analysis of S. inferens population with weather parameters showed that there was 80 per cent (HQPM1) and 82 per cent (HKI 1128) variability in larval population due to various environmental factors. The population dynamics revealed by this study have far reaching significance in pest management strategy as integrated control measures may be focused only during the period wherein population exceeds economic threshold level (ETL).