Insecticidal activity of a novel fatty acid amide derivative from Streptomyces species against Helicoverpa armigera

Abstract

Helicoverpa armigera, an important pest causes serious damage to grain legumes. The main objective of this study was to isolate and identify the metabolite against H. armigera from a previously characterised Streptomyces sp. CAI-155. The culture filtrate of CAI-155 was extracted using Diaion HP-20 and the active fractions were fractionated on Silica and C18 column chromatography. The C18 active fraction was further fractionated on Silica gel 60 F₂₅₄ thin layer chromatography (TLC). The most active fraction (Rf 0.64) purified from TLC led to the identification of a novel metabolite N-(1-(2,2-dimethyl-5-undecyl-1,3-dioxolan-4-yl)-2-hydroxyethyl)stearamide by spectral studies. The purified metabolite showed 70–78% mortality in 2nd instar H. armigera by diet impregnation assay, detached leaf assay and greenhouse assay. The LD₅₀ and LD₉₀ values of the purified metabolite were 627 and 2276 ppm, respectively. Hence, this novel metabolite can be exploited for pest management in future.

Keywords:

• Helicoverpa armigera
• Streptomyces
• biological control
• pest management

Acknowledgements

The authors are grateful to the Department of Biotechnology, Government of India for funding this study. This work was undertaken as part of the CGIAR Research Program on Grain Legumes. ICRISAT is a member of CGIAR Consortium.

Funding

This work was supported by the Department of Biotechnology, India [grant number BT/PR13824/AGR/05/508/2010].