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调查102株落叶松,结果表明,落叶松红腹叶蜂[Pristiphora erichsonii(Htg)]幼虫在树冠上的垂直分布规律是:初龄幼虫,由上层向下层虫口密度逐渐减少,上层虫口密度通常为下层的9倍以上,最多可达20倍。老熟幼虫,则由上、下、中逐渐递增,以中层最多。水平分布是:当年枝段较为最少,前两年为最多,为当年生枝段的1倍以上。根据幼虫在树冠上的分布规律,讨论如下问题:①调查幼虫虫口密度时,应以树冠上、中、下分层取样,所得结果更接近于实际,②样枝长度以年生长枝段为单位要好于常规样枝长度。
The investigation of 102 larches showed that the vertical distribution pattern of larvae of Pristiphora erichsonii (Htg) on the crown of the larvae was as follows: the larvae of the first instar larvae gradually decreased in density from the upper layer to the lower layer, and the population density of the upper layer was usually The lower 9 times more, up to 20 times. Mature larvae, from the upper and lower, gradually increasing to the middle of the most. Horizontal distribution is: when the branches are the least, the first two years is the most, for the year branches more than 1 times. According to the distribution of larvae in the canopy, the following questions are discussed: ① When the population density of larvae is surveyed, the samples should be sampled by the upper, middle and lower canopy layers. The results are closer to the actual ones. ② The length of the shoots is based on the annual growth branch It is better than the normal sample length.