青海云杉种实害虫发生危害研究

青海云杉种实害虫的主要种类为云杉球果小卷蛾,主要发生于天然林及母树木,虫害株率高达100%.-般低海拔林分重于高海拔林分,老母树林重于新母树林,纯林、疏林重于混交林和郁闭林分,远离天然林的种子园没有种实害虫的发生.在同一坡面上,随坡位升高虫害减轻,平缓林分重于陡坡林分,不同坡向间差异不明显;干燥林分重于湿润林分.平均单果虫口密度3头左右时,虫害果较健康果相比,出种率下降2.5%,健饱种数下降18.3%,虫蛀种子率达16.2%,千粒重下降0.93g,发芽率降低28%.

Occurrence and Damage of Cone and Seed Insects in Picea crassifolia

Psendotomoides strobilellus(Linnaeas) is an important cone and seed insect in Picea crassifolia in Qilianshan Mountain,Gansu Province,and it mainly occurs in the natural forest and seed stands.The infection rate would even be 100%.Stands at low elevation are severer than those at higher elevation;old-grown seed stands severer than new established ones;pure forest stands and sparse-densitied stands severer than closed stands or mixed forest stands;drier stands severer than humid stands;stands in higher position of slope severer than those in lower position of slope.Seed garden far from natural forest is free from pest and disease infection.Comparison of infected cones averaging 3 pests with healthy ones showed that seed amount declined by 2.5 %,full-filled seed reduced by 18.3 %;pest damage rates 16.2%;thousand grain weight decreased by 0.93g and germination rate lowered by 28%.