Insecticidal activity of a novel fatty acid amide derivative from <i>Streptomyces</i> species against <i>Helicoverpa armigera</i>

<p><i>Helicoverpa armigera</i>, an important pest causes serious damage to grain legumes. The main objective of this study was to isolate and identify the metabolite against <i>H. armigera</i> from a previously characterised <i>Streptomyces</i> 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 <i>N</i>-(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 <i>H. armigera</i> 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.</p