云南松毛虫预测预报技术的研究

Techniques of forecasting and predicating Dendrolimus houi

通过对云南松毛虫幼虫饲养观察 ,得出该虫幼虫共有 7龄 ,平均取食量为 1 0 4 4g ;4龄以后取食量开始明显放大 ,因此 ,防治该虫应安排在 4龄以前进行。该虫 1～ 2龄幼虫死亡率较高 ,为 30 %～ 60 % ,3龄以后死亡率降低 ,虫口数量比较稳定 ,是开展测报调查的最好时机。确立了以柳杉树冠直径推算柳杉针叶量的关系式 :lgW =a +blgD ,以此建立柳杉树冠级数表和虫灾级数表 ,该虫的空间分布型为聚集分布 , m对m回归式为 : m=1 4 2 75 7+ 1 1 2 4 0m ,建立了以底部 2根枝条平均虫口数量来预测全树虫口数量的预测式 :y =9 75 4 4x1 1574,既符合一定精度要求 ,又简便易行 ,提高工作效率。表 7参

By raising and observing the larva of Dendrolimus houi, it is known that the larva is 7 instars.Their average appetite is 104 4 g and increases distinctly after 4 instars.Therefore,the prevention and control of the insect shall be carried out before 4 instars.The 1～2 instar larva has a high death rate,accounting for 30%～40%.The death rate decreases after 3 instars and their population is stable.It is the best opportunity to carry out forecast and investigation.The formula to calculate the leave quatity by the diameter of Cryptomeria fortunei crown is lg W = a + b lg D .The formula establishes the grade of Cryptomeria fortunei crown and insect pest.The formula of the distribution pattern of the insect is [SX(B-4]m =14 275 7+1 124 0 m .The formula for the predication of population of insect number in a tree by the average insect number in two lower branches is y =9 754 4 x 1 157 4 .These formulas conform to the requirement for precision and promote the working efficiency.