The Insecticidal Activity of Secondary Metabolites Produced by Streptomyces sp. SA61 against Trialeurodes vaporariorum (Hemiptera: Aleyrodidae)

<i>Trialeurodes vaporariorum</i> Westwood poses a significant threat to vegetable and ornamental crops in temperate zones, resulting in notable reductions in yield and substantial economic burdens. In order to find compounds with high insecticidal activity against <i>T. vaporariorum</i>, five compounds were isolated and identified from the crude extract of <i>Streptomyces</i> sp. SA61. These include three new polyketides, named strekingmycins F-H (<b>1</b>-<b>3</b>); one new diterpenoid, named phenalinolactone CD8 (<b>4</b>); and one known compound, strekingmycin A (<b>5</b>). Their structures were analyzed using high-resolution electrospray ionization mass spectrometry and one-dimensional and two-dimensional nuclear magnetic resonance spectroscopy data and by comparing them with previously reported data. The insecticidal activities of compounds <b>1</b>-<b>5</b> against <i>T. vaporariorum</i> were evaluated. Among them, compound <b>5</b> exhibited the highest insecticidal activity, with an LC₅₀ of 6.949 mg/L against <i>T. vaporariorum</i> at 72 h using the leaf-dip method. Lower insecticidal activities were found in compounds <b>1</b>-<b>4</b>, with LC₅₀ values of 22.817, 19.150, 16.981 and 41.501 mg/L, respectively. These data indicate that strekingmycin could be a potential candidate for a novel insecticide to control <i>T. vaporariorum.</i>