水稻褐飛蝨的經濟爲害水平之研究　Ⅰ．在褐飛蝨各棲羣密度施藥防治對稻穀收量及收益之影響

Determination of the Economic Injury Levels of the Brown Planthopper in Taiwan Ⅰ. Control of the Brown Planthopper at Various Population Density in Relation to Grain Yield and Net Return

鄭清煥(C. H. Cheng)

《中華農業研究》 27卷3期 (1978/09) Pp. 229-236

https://doi.org/10.29951/JARC.197809.0004

摘要

在本省嘉南地區，經過六次田間試驗發現，稻穀產量明顯隨施藥時褐飛蝨之棲羣密度的增高而減少。按目前稻穀價格（保證收購或市面價格）及防治成本計算，供試三種感蟲品種，嘉農秈8號，臺中在來1號及臺南5號，無論在褐飛蝨發生密度高或低的情況下，多以每叢水稻褐飛蝨之密度平均在10隻水平或10隻以下即施藥防治所獲的純收益最高，較之褐飛蝨密度到達20隻／叢水平始施藥防治者約平均增加9另左右，而較一般農民約在40隻／叢水平以上始施藥處理者約平均增加20%。根據此項試驗結果，目前大力地推薦在褐飛蝨密度到達20隻／叢以上才有防治價值之標準應予修正，以增加稻穀產量及農民收益。

並列摘要

This study was conducted to determine the economic injury levels of the brown planthopper under field conditions ay artificial control of the insect as soon as its population reached the indicated population levels. Three insect susceptible cultivar, Chiann Sen 8, Taichung native 1 and Tainan 5 and four different cost insecticides were adopted in this study. The result of these experiments indicated that the grain yield differed significantly among the treatments, decreasing the yield with the increase of insect population level which the chemical application was opperated. Based on the prices of rice grain and the costs of the artificial control at present in Taiwan, the treatment with chemical application as soon as the brown planthopper reached the level of 10 insects per hill or below this level obtained the highest net return profit, about 9% and 20% higher than those treated while the insect population reached the levels of 20 and 40 insects per hill, respectively. Therefore, it is suggested that present recommending the use of economic threshold of the brown planthopper, about 25 insects per hill should be changed into 5-10 insects per hill to get higher grain yield and net return profit from the control of the planthopper.