Journal of Taiwan Agricultural Research

Author:Edward Y. Cheng, Wen-Ying Su, Yu-Bing Hwang*, Ming-Yao Chiang and Ching-Hua Kao

Abstract:

    A 10-day density monitoring system for the oriental fruit fly, Bactrocera dorsalis, has been used for the area-wide control program in Taiwan since 1994. This monitoring method records average catch of fruit flies over ten days, which can reduce the day to day variation and provides a stable report. However, the 10-day monitoring data can not be applied in an urgent situation, and a rapid monitoring technique to complement the existed system has been developed. Major criteria for the rapid monitoring technique are shortening the survey time to less than one hour, and the obtained data should be comparable to current 10-day monitoring data. Field experiments had been performed from June to December of 2003, a period without low temperature that might hamper the activity of fruit flies. The testing field covering acreage of more than 17,500 hectares is located in Wufeng, Tsaotun and Fenyuan areas that crossing Taichung, Nantou and Changhua counties. Sixty-eight surveying spots were chosen to establish both 10-day and rapid density monitoring data, and the distance between any two surveying spots is more than one kilometer. Rapid density detection technique was tested in individual surveying spot on the 10^th day by applying the umbrella-type trap baited with naled and methyl eugenol mixture. A collecting net (40 cm in diameter and 60 cm height) was hanging under the trap, and a 100 cm Î100 cm white plastic cloth was placed on the ground to help visualizing the attracted fruit flies. Three observation traps, each is one hundred meter afar from the number of flies attracted/killed was recored. Four observation teams, a two-person team and three single person teams, were dispatched for the field experiment. Accumulated 10-day and rapid density monitoring data were analyzed for possible correlations, and the results indicated that the coefficient of correlation (r) between data of two methods only ranged from 0.24 to 0.42 for single person team, while is 0.7-0.73 for the two-person team. Consequently, the data obtained from the two-person team was used to develop the correlation model between the 10-day and the rapid density monitoring methods. The obtained data had gone through the log transformation for statistic analysis to establish a correlation equation, Y=0.41X, and the determined coefficient (R²) exceeds 0.93.

Key words:Rapid density detection technique, Bactrocera dorsalis

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