東方果蠅DACUS DORSALIS HENDEL為害木瓜調查

Abstract

東方果蠅在木瓜園週年均有出現，以夏、秋兩季最多，冬季次之，春季最少。其在一天中之活動，乃隨氣溫之高低而不同。上午9時之氣溫在22℃以下，則出現之蟲數，多在9時至15時之間。但在25℃以上，則以天亮至9時之間出現最多。天氣之變化亦可影響其出現之多寡，一般以高溫而晴朗的天氣出現最多，陰雨時較少，低溫（14℃以下）而又陰天未有誘得的紀錄，但雨後放晴，則其蟲數突較常日為多。 調查各成熟度日陞品種木瓜4,735個，及高寶品種木瓜1,275個，始終沒有篩到一個東方果蠅的蛹，亦沒有東方果蠅在木瓜果實上產卵之跡象。在臺灣之自然狀態下，供商業販賣採收成熟之木瓜果實，尚未發現東方果蠅之為害。 The investigation was carried out during 1973 to 1975. Field evidences revealed that the Oriental fruit flies visited the papaya orchards all year round. The peak population increased to its highest during the summer and autumn seasons, and decreased to the lowest in spring. It was positively related to the temperature as well as the growing conditions of papayas. The activity of the flies during the day time was chiefly influenced by both temperature and weather. When the temperature was below 22°C the flies appeared more between 9:00 a. m. to 15 00 p. m. and the higher the temperature rose the earlier the flies appeared, but activity paused when the temperature went down below 14°C. Flies came out in large numbers on sunny days and less on rainy day. Sometimes they swarmed out suddenly in large numbers on sunny days followed by several days of cold and rain. The experimental papaya fruits were divided into five degrees of maturity in order to examine the damage due to fruit flies. A total of 4,735 fruits of the variety Sunrise Solo and 1275 fruits of Kapoho Solo were taken from the experimental field for laboratory examination. There was no pupa of fruit flies found during the 24 months of investigation, even no trace of deposition of eggs on the surface of papaya fruit. According to Misaka (三板) (1938) , who had previously investigated papaya fruits in Taiwan, no evidence of damage of fruit flies on papaya fruits was found in fields under natural conditions.