Dinh Thi Chi * and Le Van Vang

* Corresponding author (dtchi@stcc.edu.vn)

Main Article Content

Abstract

The diamondback moth (Plutella xylostella) is one of the most destructive pests of cruciferous vegetables in the Mekong delta of Vietnam. In order to application of sex pheromones as tool for a sustainable management program, the sex pheromone components of P. Xylostella, (Z)-11-hexadecenal (Z11-16:Ald), (Z)-11-hexadecenyl acetate (Z11-16:OAc) and (Z)-11-hexadecen-1-ol (Z11-16:OH), were synthesized and evaluated their attraction in field. The synthetic route using Wittig reaction as key reaction successfully synthesized Z11-16:OH and its corresponding Z11-16:Ald and Z11-16:OAc compounds. After protecting the hydroxyl group of 11-bromo-1-undecanol by methoxymethoxy (MOM) ether, the protected compound was heated with triphenylphosphine at 100oC 24 hrs. to form a phosphonium salt which was converted to MOM ether of (Z)-11-hexadecen-1-ol compound by coupling with pentanal under the catalyst of sodium bis(trimethylsilyl)amide solution in THF (Wittig reaction). Stirring of the MOM ether compound in 0.5N HCl solution in methanol 24 hrs. to remove hydroxyl protection obtained Z11-16:OH compound (isomeric purity was >96% as checked by GC-MS analysis). Yield of the synthetic route (from 11-bromo-1-undecanol to Z11-16:OH) was 42.9%. Following, PCC oxidation and acetylation of Z11-16:OH gave Z11-16:Ald and Z11-16:OAc, respectively. In field examinations, traps baited with synthetic lures prepared from different mixtures of Z11-16:Ald, Z11-16:OAc and Z11-16:OH caught significantly higher number of P. xylostella males than that of control affirming the attractiveness of synthetic pheromones. However, only the attraction of three components lures were as strong as that of a virgin female. Otherwise, only traps baited with two components lures prepared from Z11-16:Ald and Z11-16:OAc caught more P. xylostella males than those of traps baited with single component lures. These indicated that Z11-16:Ald and Z11-16:OAc were actively obligated components while Z11-16:OH was a syergistic component for the attraction of P. xylostella in the Mekong delta of Vietnam.
Keywords: Plutella xylostella, sex pheromone, (Z)-11-hexadecen-1-ol, (Z)-11-hexadecenal, (Z)-11-hexadecenyl acetate

Article Details

References

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