水稻白背飛蝨之族群變動及發生預測

"Population fluctuations and forecasting of the white-backed planthopper, Sogatella furcifera on rice in Chiayi region, Taiwan"

本文係利用1982至2002年水稻害蟲偵察田及誘蟲器材調查資料，分析白背飛蝨在嘉義地區稻田之族群變動、影響族群發生豐度因子並藉以建立發生預測模式，結果顯示白背飛蝨近年來之發生族群密度有逐年增加之趨勢，可能受海外遷入蟲數增多所致。在暖冬年白背飛蝨在嘉義地區以少量成蟲於再生稻上越冬，越冬成蟲於12月下旬至1月上旬遷入一期早植稻繁殖一世代，於3月末至4月初擴散至中、晚植稻，族群高峰出現於5月下旬至6月上旬之第三世代若蟲期，發生豐度主要受4月下旬至5月上旬之遷入蟲量所影響。在第一期稻收割後之再生稻上，以由外地遷入之長翅型成蟲為主，若蟲極少。在第二期稻，白背飛蝨之族群受水稻栽植期及海外成蟲之遷入期及遷入量所左右；早植稻通常有較高之遷入蟲。在早、中植稻上白背飛蝨之族群高峰可能出現於第五代及第六或第七世代若蟲期，隨害蟲之遷入期及遷入量而定，而在晚植稻則多出現於第六或第七世代若蟲期。族群豐度主要受8月遷入蟲量的影響，9及10月的溫度對族群的豐度呈顯著的正相關，而8月高溫及9月、10月的降雨量則對白背飛蝨的族群豐度具顯著的負面作用。在10月下旬或11月上旬後，第八世代之白背飛蝨族群密度急遽下降。二期稻收割後白背飛蝨以成蟲在再生稻上越冬，但除少數年度於12月至翌年1月尚可捕獲少量成蟲外，大部分年度幾無所獲。利用逐步回歸分析，已建立若干供預測第一、二期稻白背飛蝨發生豐度之模式，可供進一步測試其適用性。

"The white-backed planthopper (abbr. WBPH) (Sogatella furcifera (Horvath), Homoptera: Delphacidae) is an important insect pest of rice in Taiwan occasionally. Present study was conducted to investigate its population fluctuations, to determine the factors affecting abundance, and to develop the models for forecasting its population abundance based on the data collected from the monitored fields and traps from 1982 to 2002 in Chiayi region. According to the catches of adult by traps and the population monitoring in paddy fields, the population of WBPH in recent years tended to increase distinctively, especially in the second cropping season. It was observed that the WBPH could overwinter on ratooning rice in Taiwan with a very low population of macropterous adult which could supposedly migrate to the early-planted rice of the first cropping season from late December to the beginning of January. The adults of the first generation from the early- planted rice appeared from late March to early April and most of them migrate to the later planted rice. The population peak in the first cropping season mostly appeared during the nymphal stage of the third generation from late May to early June. However, the population abundance in the third generation was positively correlated with the total catches of air-borne net trap from late April to early May, but not with the overwintered population, indicating the influence of immigrant population affecting its peak population was greater than that of locally overwintered population. On ratooning rice of the first cropping season, very rare nymph could be observable, except macropterous adults. In the second cropping season, the WBPH went through 3 to 4 generations. The populations of the insect in paddy fields were greatly affected by the date and population of immigrants as well as the planting time of rice. The early-planted rice usually received higher population of the immigrants, and the population peak mostly appeared in the fifth generation, while in the common (middle) or later-planted rice, the population peak appeared in the nymphal stage of the sixth or seventh generation, but mostly in the seventh generation in the later planted rice. Population abundance was positively correlated with the total catches by light trap in August, and the temperature in September and October, but it was negatively correlated with the average temperature in August and rainfall in September and October. The population declined sharply in the eighth generation from late October to early November, and macropterous adults could rarely be observed on ratooning rice from December to early January in a few years. Several models for forecasting its population abundance both in the first and second cropping season were developed for further tests of their validity."