Regulation of pakchoi's secondary metabolites on the behavior of female Plutella xylostella (Lepidoptera: Plutellidae)

To clarify the regulation of pakchoi’s secondary metabolites on the behavior of Plutella xylostella L., Various polar substances from pakchoi using the heat reflux method were extracted. The regulation of these substances on the behavior of female P. xylostella was evaluated with a Y-tube olfactometer, and the chemical structures in the extract were identified by GC-MS. The results showed that all the extracts with varying polarities of pakchoi regulated the behavior of female P. xylostella. The low-polarity substances attracted females at high concentrations, and the high-polarity substances lured females at medium and low concentrations. Comparing the anhydrous-ethanol extracts with the distilled-water extracts of pakchoi, the former had lower attractant activity to P. xylostella than the latter at low concentrations. The results of GC-MS identification showed that the distilled-water extracts of pakchoi contained two compounds, namely ethyl iso-allocholate and 9,12,15-octadecatrienal, among which the concentration of ethyl iso-allocholate was higher. The anhydrous-ethanol extracts of pakchoi contained six compounds, the substance with the highest concentration was 3,7,11,15-tetramethyl-2-hexadecen-1-ol, followed by 9,12,15-octadecene carbtrienoic acid, in which 9,12,15-octadecatrienic acid and 9,12,15-octadecatrienal had the same parent ring structure. The results showed that 9,12,15-octadecatrienic acid and 9,12,15-octadecatrienal were the substances with potential activities to regulate the behavior of P. xylostella on pakchoi, which could be used for the development of lead compounds for the green control of P. xylostella.