Investigations on population dynamics of diamondback moth, Plutella xylostella Linn. and natural enemies on cabbage, Brassica oleracea var. capitata Linn

Abstract

The study on population dynamics of diamondback moth larvae on cabbage variety, Golden Acre revealed the commencement of pest in 50th SMW and maximum larval population on 1st SMW. The larval population showed highly significant negative correlation with maximum, minimum and average temperature. Wind speed had significant positive correlation with the larval population. Coccinellid predators viz., Coccinella transversalis Fabricius and Cheilomenes sexmaculata (Fabricius) were noticed in cabbage ecosystem. The initial occurrence of coccinellids were noted during 50th SMW and the population increased gradually in successive weekly counts and reached a peak in 3rd SMW. The minimum and average temperature and the evening relative humidity had significant negative effect on the population of coccinellid beetles. Wind speed had highly significant positive influence on coccinellid population. Regression studies revealed 76.90 and 80.70 per cent association of P. xylostella larval population and coccinellids with significant weather parameters, respectively.