Antifeedant properties and contact toxicities of the trichocellins A-I and B-II from a Trichoderma reesei against Plutella xylostella larvae

Plutella xylostella is a destructive cabbage pest responsible for huge economic losses. Heavy and continuous application of synthetic pesticides to control this pest has resulted in numerous environmental issues. Thus, discovering alternative methods to control P. xylostella, with reduced harmful effects has become crucial. In the present study we investigated the antifeedant activities and contact toxicities of two peptaibiotics, trichocellin A-I and B-II, produced by an endophytic fungus Trichoderma reesei against P. xylostella larvae. The two compounds were isolated using bioassay guided chromatographic methods from an ethyl acetate extract of T. reesei, isolated from the sedge Cyperus iria. The chemical structures of the two compounds were elucidated using mass spectrometric and NMR data. Both trichocellins showed 100% feeding deterrence activity against P. xylostella while the DC50 value for trichocellin A-I was 2.38 µg cm−2. The amount isolated was not sufficient to determine the DC50 value for trichocellin B-II. In addition, both compounds showed moderate contact toxicities against P. xylostella larvae having a mean motility around 40–50%. Trichocellin A-I and B-II, have previously been reported as having antibiotic properties. However, this is the first study to report the antifeedant and contact toxicities of trichocellin A-I and B-II against the economically important insect pest P. xylostella. The results of this study encourage further investigation of secondary metabolites of Trichoderma species for development as natural pest control agents in agriculture.