INFLUENCE OF WEATHER ON MALE MOTH CATHCES OF SPODOPTERA LITURA IN PHEROMONE TRAPS AND INFESTATION IN VIRGINIA TOBACCO

Abstract

Tobacco caterpillar, Spodoptera litura Fab. is a polyphagous pest infesting several crops including tobacco. Field experiments were conducted to study the interrelationship between the male moth catches in pheromone traps with weather parameters and the pest infestation in Virginia tobacco field crop for three seasons (2010 -13). During 2010-11, the trap catch was highest in the 7th standard week (83/trap). The correlation between trap catch, egg masses, larvae and increase in per cent plants damaged was highly significant during the season. The multiple linear regression equation for plants damaged vs. moth catch, egg masses and weather parameters explains 69.6 per cent variability of the dependent variable by pheromone trap catch together with weather parameters. During 2011-12, the trap catch was highest in the 2nd standard week (22.5/trap) followed by 8th (20/trap) and 3rd (18.25) standard weeks. The correlation between trap catch, egg masses, larvae and increase in per cent plants damaged was not significant during the season. The multiple linear regression equation for moth catch in pheromone traps vs. weather parameters explains 50.3 per cent of variation in the moth catches in pheromone traps and about 50 per cent variation in the dependent variable is unexplained. During 2012-13 the trap catch was highest in the 8th standard week (20.5/trap). The correlation between trap catch, egg masses, larvae and increase in per cent plants damaged was positive and highly significant. The fitted multiple linear regression equation for increase in per cent plants damaged vs. moth catch and weather parameters explain 76.1 per cent variability of the dependent variable by pheromone trap catch together with weather parameters.