台灣水稻害蟲發生趨勢與防治展望

Abstract

水稻為台灣栽培面積最大的作物，水稻害蟲之發生隨著栽培品種、耕作制度及政策之方向而改變，目前台灣水稻第一期作主要害蟲種類為二化螟、斑飛蝨及局部地區之水稻水象鼻蟲；二期稻則以水稻縱捲葉蟲、稻飛蝨類（褐飛蝨、白背飛蝨及斑飛蝨）、螟蟲類（大螟及二化螟）為主，其中除了地方性害蟲種類（如螟蟲類）及境外入侵種類（如水稻水象鼻蟲）外，尚有隨著氣流長距離遷移進來之害蟲種類（如褐飛蝨、白背飛蝨及水稻縱捲葉蟲等）。經分析1985-2007長期監測資料顯示白背飛蝨、斑飛蝨及水稻縱捲葉蟲之族群密度有逐年增加之趨勢，其原因與海外遷入蟲源（包含害蟲種類及數量）及台灣水稻耕作制度改變有關。白背飛蝨及褐飛蝨於7-8月間之遷入蟲量，為影響水稻二期作害蟲族群發生之主要蟲源。有效偵（監）測海外遷入蟲源及其族群變化（包含種類、生物小種及抗藥性等）等，為擬定適當防治策略之重要資訊。另外，發展省工、省時等經濟栽培之綜合管理方法，亦為未來防治研究發展方針之一。在台灣，各區域研究場所除基本之偵（監）測調查及水稻害蟲防治研究外，尚需要各領域研究學者相互合作（如電腦模擬預測模式、害蟲生物小種及抗藥性監測等）、長期監測執行，並建立害蟲族群發生之預測程式，才能使台灣水稻害蟲防治更趨完善，以確保台灣水稻安全生產。 Rice is the largest cultivation crop in Taiwan. The shifts of rice insect pests mainly depend on the rice varieties, cultural pratices and so on. Nowadays, the major rice insect pests are the rice stem borer (Chilo suppressalis), smaller brown planthopper (Laodelphax striatella), rice water weevil (Lissohoptrus oryzophilius) in the first cropping season and the rice leaffolder (Cnaphalocrocis medinalis), brown planthopper (Nilaparvata lugens), whitebacked planthopper (Sogatella furcifera), smaller brown planthopper, rice stem borer, pink borer (Sesamia inferens) in the second cropping season. Among them, rice borers are domestic species, the rice water weevil is an invasive species and the rice planthoppers and rice leaffolder are immigrant species although they could overwinter in low population in Taiwan. Analysis of the light trap data of last 23 years (1985~2007) in Sikou, Chiayi county showed the population of the whitebacked planthopper, smaller brown planthopper and rice leaffolder tended to increase in the second crop season, and it seemed to be related with the change of species and numbers of immigrant and cultural practices in Taiwan. The population of whitebacked- and brown planthoppers during July to August were closely correlated to the occurrence of the two species in the following successive generations in paddy fields. Monitoring the immigrants species and the properties of populations including the biotypes, chemical resistance and so on is the most important factor for making the decisions of control. In addition, developing the time- and labor-saving methods for economic control of the rice insect pest is also important in the future. We suggest that the occurrence of pests in each district research stations has to be monitored periodically in order to develop proper methods for control of the pests accordingly. Further more, we also need to cooperate with other disciplines for developing the computer simulation model of immigrants, monitoring the biotypes and chemical resistance, forecasting systems of the pests and so on, to enable a better management tactics, and ensure the safety production of rice in Taiwan.