桑蓟马经济阈值的研究

Economic Threshold of the Mulberry Thrips Pseudodendrothrips mori ( Niwa)

利用秋季桑蓟马为害后造成不同受害水平的桑叶饲育家蚕，研究了不同受害水平桑叶及其蚕茧的损失，建立了桑蓟马虫日指数（Ｘ）与桑叶产量损失率（Ｙｍ）和茧层量损失率（Ｙｓ）的关系式。根据江西省南昌地区蚕茧收购价格及害虫防治有关的经济数据，得到桑蓟马经济阈值ＥＴｓ为５３８虫日，属３级受害水平；考虑大草蛉对桑蓟马的捕食作用，则桑蓟马经济阈值可定为４级受害水平。

The experiments, in which silkworms were bred with the mulberry leaves of various injury levels caused by the mulberry thrips, Pseudodendothrips mori (Niwa), were conducted to determine the relationship between the yield loss of mulberry leaves ( Y m) and the loss of silkworm cocoons ( Y s). It was that: Ym =-0.005 32+0.000 29 X ( r =0.990*8]7**); Ys=-0.001 39+0.000 11 X ( r =0.985 3**)According to economic data for controlling the thrips and the prise of silkworm cocoons in Nanchang, Jiangxi Province, the economic threshold of the pest was calculated to be 538 insect-days, it was the third injury level of mulberry leaves caused by the thrips, in which the injured area of a leaf covered 1/2 to 3/4 of the whole leaf.