麦鞘毛眼水蝇为害损失与经济阈值的研究

1989—1990年在甘南藏族自治州合作地区选用青棵农家品种“肚里黄”为试验材料,根据麦鞘毛眼水蝇(IIydrellia chinensis Qi et Li)为害特点,应用田间自然种群与药剂处理相结合的方法,通过线性回归分析、相关分析及通径分析、对青稞不同受害程度与产量损失的关系进行了研究。结果表明:“肚里黄”品种旗叶叶鞘受害程度的大小对青稞千粒重产量的形成有明显的影响,而其它叶鞘的影响不明显;经回归分析,平均严重度(X_2)、为害指数(X_3)与产量损失率(Y)的关系式分别为:Y=4.1599 0.4962X_2和Y=5.4197 0.4718X_3;空壳率的上升是造成产量损失的直接因素;在自然条件下,其经济阈值的数学模型为: X=1/2.58977CN(10.8737CN C_1)(卵量) 据此,合作地区麦鞘毛眼水蝇的防治指标为拔节后期单株卵量4.2粒。

STUDIES ON THE DAMAGE AND ECONOMIC THRESHOLD OF WHEAT SHEATH MINING FLY TO HIGHLAND BARLEY

Based on the investigations of different damage levels in field plots of "Dulihuang", a local variety of highland barley , caused by natural population of wheat sheath mining fly Hydrellia chin-ensis Qi et Li, controlled by different omethoate treatments and a series of data processings such as linear regression , correlation and path analyses, the relationship between the injury of this insect pest and the yield loss of the host plant was studied in Hezuo District, Gannan Tibetan Autonomous Prefecture in 1989-1990. The results showed that there was close correlation between the damage levels on flag leaf sheath and thousand kernel weights , and the damages on other leaf sheaths were ineffective on the kernel weight. The regression equation of mean severity (X?) and injury index (X3) to yield loss rate (Y) were developed as . Y=4. 1599 0. 4962X2, Y = 5. 4197 0. 471 8X3, respectively. The increase of sterility rate was the direct factor causing yield loss. An economic threshold (egg number) model under natural condition was developed as : where, the X - economic threshold (egg number) ;C1 - cost of control ;C - unit price of highland barley production ; and N - production of highland barley without injury. Consequently , the action thresnold of H. chinensis in Hezuo District in late jointing stage was 4. 2 eggs/plant.