Field Evaluation of an Indigenous Granulosis Virus Isolate for Pieris brassicae (Linnaeus) Management under North Western Himalayan Conditions

Abstract

A granulosis virus strain infecting Pieris brassicae (PbGV) was isolated from the dry temperate region of Northwestern Himalayas as a potential microbial agent for the management of P. brassicae. Host specificity and safety to parasitoid Cotesia glomerata (L.) revealed high host specificity and safety to the most prevalent natural enemy. Field evaluation of PbGV was carried out alone and in combination with another microbial pesticide formulation pathogenic to lepidopteran pests viz. Bacillus thuringiensis (DIPEL®) and neem seed kernel extract (NSKE) on cole crops (cabbage, cauliflower and broccoli) at two geographically isolated locations viz. Palampur (sub tropical) and Sangla (dry temperate) in Himachal Pradesh, India in order to design ecofriendly management modules in the hill state, which is fast transforming in to organic farming. The studies revealed that the PbGV isolate alone was quite effective against P. brassicae larvae at higher dose of 1.12 í— 10¹² OBs/ha per hectare whereas at lower dose of 5.58 í— 10" LE/ha, PbGV was effective when combined with Bt or NSKE. Single foliar application of PbGV was sufficient to suppress the pest at higher altitude areas (dry temperate region) while two applications at 15 days interval were needed at low altitude areas. The findings are of great significance for exploitation of its full potential