Abstract: Season-long trapping tests during summers of 2004 and 2005 in the Yangtze-Huaihe rice-growing areas demonstrated that there were noticeable seasonal shifts for trapping Chilo suppressalis males. As for trapping the first generation, a four-component lure (162.3 μg Z-11-hexedecanal, 81.3 μg Z-9-hexedecanal, 56.4 μg hexedecanal, and 30.3 μg Z-13-octadecenal) produced approximately 5-fold trap catches as did the standard pheromone lure of C. suppressalis reported. This ratio was significantly different with the ratios of the over-wintered and the second generation ranging from 1.52 to 1.87.Trap catch depended on the ratio of Z11- and Z9-hexedecanal, but did not depend on either component dosage or the total dosage. The optimal ratio of Z11- and Z9-hexedecanal for field trapping might change with different night-temperatures, and the declining of trap catch in the first flights might be due to the inappropriate ratio of Z11- and Z9-hexedecanal contained in the standard pheromone lure of C. suppressalis.

Key words: Chilo suppressalis; pheromonal blend, lure, (Z)-11-hexedecanal, (Z)-9-hexedecanal