Volatile organic compounds mediated non-preference for oviposition and feeding of hairy caterpillar, Spilosoma obliqua Walker (Lepidoptera: Erebidae) in jute

Abstract

Aim: To identify the volatile organic compounds (VOCs) from wild and cultivated jute species imparting varying degree of non-preference for oviposition and feeding to jute hairy caterpillar, S. obliqua Walker. Methodology: Different host species of S. obliqua viz., Corchorus olitorius, C. aestuans, C. pseudo-olitorius, C. fascicularis, C. tridens and C. trilocularis were used to find out the feeding and oviposition preference of S. obliqua. Headspace volatiles were collected from different genotypes of jute and the chemical analysis was done with Gas chromatography - Mass Spectrometry (GC-MS). Results: The chemical compounds of VOCs responsible for causing non-preference mechanism of host plant selection to S. obliqua. The chemical complexity and chemistry of volatiles from cultivated and wild jute species indicated significant variation. The VOCs identified in C. aestuans was comparatively more than cultivated species and were different from other cultivated and wild species of jute. Very low preference index for larval feeding and oviposition preference of S. obliqua was due to the possible deterrent effect of volatile organic compounds. Interpretation: The GC-MS analysis of VOCs from C. aestuans (WCIN-179) indicated strong repellent action on S. obliqua that makes it resistant due to non-preference mechanism resulting in less preference for egg laying and feeding. The uniqueness and novelty of C. aestuans confirmed on the basis of very unique VOCs profile which makes it resistant against S. obliqua through multiple mechanisms, i.e., antibiosis and non-preference recording least suitable for egg laying, biology and growth of insects. Key words: GC-MS, Hairy caterpillar, Jute, Oviposition, Volatile Organic Compounds