Camelliasaponins A1 and A2 extracted from camellia (Camellia japonica var. japonica) seeds are key antifeedant compounds against the larvae of diamondback moth (Plutella xylostella L.)

Plutella xylostella (diamondback moth) is a major pest of cruciferous crops, causing substantial global economic losses. Therefore, this study aims to isolate natural antifeedant compounds from Camellia japonica seeds and evaluate their bioactivity against third-instar larvae of P. xylostella. Among the tested plant extracts, the ethanolic extract of C. japonica seeds exhibited strong antifeedant activity, with a 50 % antifeedant concentration (AFC₅₀) of 128 ppm. LC-MS/MS analysis of the extract identified major constituents, including disaccharides (17 %), kaempferol glycosides (12 %), camelliasaponin A1 (10 %), camelliasaponin A2 (11 %), and other triterpenoid glycosides. Subsequent medium-pressure liquid chromatography (MPLC) fractionation of the extract produced five fractions, one of which showed antifeedant activity at 125.0 ppm. This active fraction contained high levels of camelliasaponins A1 (5,031 ± 286 ppm) and A2 (6,053 ± 185 ppm). Authentic camelliasaponin A1 and A2 also showed potent antifeedant activity against P. xylostella larvae, with AFC₅₀ values of 5.4 ppm and 3.6 ppm, respectively—both lower than that of neem-derived Azadirachtin (AFC₅₀ = 12.4 ppm). These findings confirm that camelliasaponins A1 and A2 are the principal active antifeedant constituents in C. japonica seed extracts. Overall, the findings highlight the potential of camellia seed extracts for development into environmentally friendly formulations for integrated pest management targeting lepidopteran larvae.