三种水稻钻心害虫防治标准的商榷

为探求害虫防治时期,和发生数量方面的防治标准,以三化螟(Tryporyza incertulas (Wlk.)、二化螟(Chilo suppressalis Wlk.)和稻瘿蚊(Pachydiplosis oryzae Wood-mason)三种水稻钻心害虫为材料,探討钻心类害虫防治标准的規律,提出如下意見: 1.关于防治时期的标准,認为可将施药时虫态的发育进度百分率数字,换算为概率单位,在概率单位为4—6时,相当于15.87—84.13％时的害虫相对发生数量,占全世代总发生数量的68.268％,可見在該段短时間(一般約十数天)的虫数,代表了虫羣的大半数,可看作标准的盛发期,在此时間数列范围內,似可作为防治时期的标准。 2.关于发生数量的防治标准,以三化螟及稻瘿蚊为例进行討論:認为应以幼虫侵入作物后至老熟(或蛹化)期間,每虫所能造成的被害株数为基础,求出幼虫密度的防治标准,然后根据調查时的不同虫态,再伸算各該虫态的防治标准。本文列举了各虫态密度防治标准的計算公式,并以广州及南京两地的三化螟和广东信宜的稻瘿蚊为例,作出在各种具体条件下,虫口密度防治标准检索表。

A DISCUSSION ON THE CONTROL STANDARD OF THREE RICE STEM BORERS

The present paper deals with the extent of abundance of insect pests in their course of appearance in relation to the control measures applied. The ecological significance of abundance and the destructiveness of Tryporyza incertulas (Wlk.), Chilo suppressalis Wlk. and Pachydiplosis orzyzea Wood-Mason, are analysed to account for the extent of abundance in which these pests should be controlled. As the percentage of development is changed into probit, the probit being about 4-6 will match the 15.87-84.13 percent of development. In this respect, the population in the whole generation will reach 68.268% and it will come to a point where the insect pest should be controlled. Formulas for controlling the larvae, eggs and moths are proposed.