褐飛蝨及白背飛蝨由海外遷入嘉南地區之偵測及其氣象條件

Abstract

褐飛蝨及白背飛蝨為臺灣水稻之重要害蟲，兩種害蟲均可少量地在臺灣越冬，亦可於每年4至8月間自華南或北呂宋隨氣流遷入臺灣。本研究之目的在於探討如何偵測其遷入、遷入時期、數量以及初步分析導引其遷入之氣象條件。以1985至1989年在嘉義偵測所得資料分析結果顯示，褐飛蝨及白背飛蝨確實可於每年4至8月間自外地遷入嘉南地區，主要遷入期為6月下旬至7月下旬。每一遷入波由2至4日不等，每年遷入波次由6至15次。在遷入期間總捕蟲數變異頗大，最大差異由氣帶式捕蟲網（air-borne net trap）之20倍至吸式誘蟲燈（suction light trap）之73倍。偵測遷入波次以氣帶式捕蟲網較為明確，但却無法偵測到較小型之遷入波；使用吸式誘蟲燈在較大遷入年對每一遷入波之判斷困難，但於較小遷入年卻可清晰地反應小型之遷入波，兩者併用可互補長短。分析導引褐飛蝨及白背飛蝨遷入之氣象條件，可類歸為鋒面型、低壓環流型（包括颱風、熱帶性低壓、移動性低壓及低壓帶）、西南氣流型及副熱帶高壓型。在嘉南地區偵測到較顯著之遷入波的氣象條件為，在850毫巴等壓面圖主要為在華南地區存有西分向氣流，風速在9 km/hr以上，並延伸至嘉南地區；或呂宋北部存有南至東南氣流，並延伸至臺灣西海岸，溫度在17℃以上；在地面天氣條件為具有西或南分向氣流，最大風速在19 km/hr以上，溫度在22℃以上，且有降雨之記錄。 The brown planthopper (Nilaparoata lugens Steil) and white backed planthopper (Sogatella furcifera Harváth) are important pest insects of rice in Taiwan. It has been known that part of the phanthopper are able to overwinter in the island, while the other individuals can immigrate from oversea every year. Present study is aimed at detecting the fact of the immigration of the planthoppers into southwestern Taiwan. Analysis of the data collected with the air-borne net trap, suction light trap, yellow water-pan trap and field survery from 1985 to 1989 revealed that the immigration of planthoppers occurred from April to August with particular distinctness in the period from mid-June to the end of July. In general, each immigration wave lasted for 2 to 4 days, but the frequence of immigration varied greatly among years depending on the meteorological conditions. Thus, the total number of the planthoppers caught by the trap differed remarkably. The maximum catches were 25 and 73 times of the minimum for the air-borne net trap and suction light trap, respectively. The air-borne net trap was more effective to distinguish the waves in the year of mass immigration, while the suction light trap was more reliable in detection of minor immigartion. Therefore, the combined use of the air-borne net trap and suction light trap was the most adequated for estimating the time, waves and density of immigrations. Analysis of meteorological factors and the immigration of planthopper to southwestern Taiwan showed that the associated weather conditions might be divided into frontal type, depression circulation type (including tropical storm, tropical depression, mobile depression and depression zone), southwestern airflow type and subtropical-hight circulation type. In addition, it was also recognized that distinct immigration was often associated with the following meteorological characterestics: 1) On the 850 mb weather chart: the southwestern to northwestern airflows with an averaged speed more than 9 km/hr was prevailent in southern China and Taiwan, or a southern to southeastern airflows extended from northern Luzon to the west coast of Taiwan, when temperature was over 17°C; 2) On the surface weather charts in Chaiyi: rainy, and the southeastern to northwest winds at a maximum speed more than 19 km/hr blew for several hours, and temperature was over 22°C.