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

Abstract

Trialeurodes vaporariorum 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 T. vaporariorum, five compounds were isolated and identified from the crude extract of Streptomyces sp. SA61. These include three new polyketides, named strekingmycins F-H (1-3); one new diterpenoid, named phenalinolactone CD8 (4); and one known compound, strekingmycin A (5). 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 1-5 against T. vaporariorum were evaluated. Among them, compound 5 exhibited the highest insecticidal activity, with an LC₅₀ of 6.949 mg/L against T. vaporariorum at 72 h using the leaf-dip method. Lower insecticidal activities were found in compounds 1-4, 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 T. vaporariorum.

Keywords: Streptomyces; Trialeurodes vaporariorum; insecticidal activity; polyketides; strekingmycin.

Figure 1

¹H-¹H COSY and significant HMBCs of compounds 1, 2, and 4. ¹H-¹H COSY—H-H correlation spectroscopy; HMBC—heteronuclear single-quantum correlation.

Figure 2

Key NOESY correlations of compounds 1 and 4. NOESY—nuclear Overhauser effect spectroscopy.

Figure 3

Chemical structures of compounds 1–5.