Seasonal abundance of fruit borer,Helicoverpa armigera(Hubner) and its impact on marketable fruit production in tomato,Lycopersicon esculentum(Mill.)

Abstract

The first appearance of Helicoverpa armigera (Hubner) was recorded in the last fortnight of December (50th and 52nd standard week), but to low ebb (0.12 and 0.10 larvae/m row) irrespective of the year of study. The initial population gradually increased and remained confined to vegetative growth but it rapidly increased during fruiting stage and attained its peak in 15th standard week (2nd week of April). Thereafter, the pest population declined. Rainfall and relative humidity were negatively correlated with the pest activity, whereas the temperature, were positive correlation with relative humidity. Likewise, temperatures were positively associated in enhancing the pest population buildup. The maximum temperature demonstrated negative impact with relative humidity in the buildup of larval population of. The first fruit infestation was recorded on 10th standard week at a low ebb irrespective years of study, which progressively increased and reached its peak i.e. 52.20 and 55.75 per cent in 15th standard week in 2005-06 and 2006-07, respectively. Thereafter, the fruit infestation declined in successive pickings.