栗山天牛幼虫和蛹在辽东栎树干上的分布规律

摘要

Massicus raddei was a new outbreak pest in the northeast of China. To analyze the distribution pattern of the pest, some oaks (Quercus liaotungensis ) in 5 plots were anatomized. The results showed that in the tree with all tops dieback, the larvae mainly lived in oak trunks below 4m and the pupae distributed in 1 - 4 m of the trunk, and in the tree with partial dieback the larvae mainly lived in the trunk below 6 m and the pupae were 3 - 7 m. The amount of larvae was positively correlated with the bark thickness, as well as with the trunk diameter. The pests were only found in the trees until the bark thickness was more than 0. 47 cm and the trunk diameter was more than 9.02 cm,. Larvae of low instar mainly lived on sunny part of trunk phloem, while most of pupae lived in xylem. In the current year, when the eggs were hatched, and until next June, the larvae fed in phloem, larvae begun to bore into xylem in June, the boring reached to a in July and August, and most of them entered xylem in September. The relationship between Number of the wormhole below 2m of the trunk was positively correlated with trunk diameter at breast height, and was negatively correlated with the highest height of living branches. The larvae occurred the most between 4 to 7 m of the height of the highest living branch.%通过解剖受害辽东栎,结合林间调查,研究栗山天牛幼虫和蛹在栎树树干上的分布规律.结果表明:受害后表现为全部枯梢症状的栎树.栗山天牛幼虫主要分布在树干4 m以下,蛹主要分布在1～4 m;部分出现枯梢症状的栎树,栗山天牛幼虫主要分布在树干6 m以下,蛹主要分布在3～7 m.天牛数量与树皮厚度和树干直径均呈正相关关系.调查发现,当辽东栎树皮厚度大于0.47 cm、树干直径大于9.02 cm时,开始出现栗山天牛危害.在林间,栗山天牛低龄幼虫主要分布在树干阳面的韧皮部中,而蛹主要分布在木质部,越靠近树干中心分布越多.产卵当年和翌年6月前幼虫主要在韧皮部取食危害.从翌年6月开始,天牛幼虫逐渐蛀入木质部为害,7-8月为蛀入木质部的高峰期,9月绝大多数幼虫蛀入木质部取食,直至化蛹.树干2 m以下的幼虫排粪孔数与树木胸径成正相关,而与最高活枝高度成负相关关系.当最高活枝高度在4～7 m时,幼虫数量最多.