Efficacy of (Z)-11-Hexadecenal and (Z)-11-Tetradecenal as Sex Attractants for Heliothis armigera on Two Different Dispensers1

Abstract

The effectiveness of (Z)-11-hexadecenal (HDA) and (Z)-11-tetradecenal (TDA) in attracting male H. armigera (Hübner) was tested with 2 types of dispensers. When dental rolls were used, a minimum quantity of 0.5 mg HDA/trap was needed for significant trap catch. However, at loadings of 0.5-5.0 mg, the initial release rate of HDA was too high and the compound was not attractive. Optimal concentration for male catches was reached only after partial evaporation in the field (during ca. 1 day). TDA at the same loadings, was active immediately after exposure, but, because of its fast evaporation failed to attract males on the 2nd and following nights. Total number of males caught and maximum catch per night were greater in traps loaded with HDA than in traps baited with TDA. On rubber dispensers, an initial load of 5 mg HDA or TDA was needed for meaningful catches. With this dispenser, TDA attracted significantly more males than did HDA, and its efficacy was positively related to the rate of initial loading. At a load as high as 50 mg/trap, TDA was released monotonically and effectively attracted males during the 17-day test period. No synergistic effect on male catches was found for a combination of (Z)-9-tetradecenal with HDA on either dental rolls or rubber dispensers.