Population dynamics of Helicoverpa armigera (Hubner) in relation to meteorological parameters.

摘要

Tomato (Lycopersicon esculentum L.) is one of the most important vegetable crops cultivated for its fleshy fruits and considered as commercial crops. The fruit borer, Helicoverpa armigera (Hubner) is most serious pest causing the maximum damage to tomato crop. Larvae appeared on tomato crop in 2nd standard week (January) and continue till 21st standard week. The highest build-up of larvae was recorded in the 15th standard week. Thereafter, the larvae population decline. The average maximum temperature 32.9 degrees C, minimum temperature of 17.9 degrees C, morning humidity 74.2%, evening humidity of 30.1% coupled with rainfall of 6.0 mm prevailing during 10th standard week to 15th standard week was found most suitable for larval population build-up. Above and below of these ranges did not favour the development of larvae. The maximum numbers of larvae were found feeding on top leaves followed by middle leaves and minimum larvae were found feeding on lower leaves. The percent of larval parasitism caused by Ecphoropsis perdistinctus (Vier) was highest in the 15th standard week, thereafter the larval parasitism decline to nil in the 18th standard week.