松根颈树皮象生物学特性和防治方法的研究

松根颈树皮象广泛分布在云南省,幼虫主要为害云南松、思茅松和华山松中幼林。幼虫钻蛀松树根颈的形成层和韧皮部,当松树受害轻时针叶变为黄褐色,受害严重时致死。松根颈树皮象二年完成一代,以成虫和5—7龄幼虫越冬。成虫在8月中开始羽化,两次越冬并生活达2年。整个成虫期都有交尾活动,但在羽化的当年不产卵。幼虫期10—14个月,主要为7—8龄,7月下旬开始化蛹,蛹期约27天。由于虫口密度较低,老熟幼虫做蛹室至成虫羽化要经过两个多月,虫期整齐,很容易用手清除。从8月下旬到9月中是最好的防治时期。

STUDIES ON BIO-CHARACTERISTICS AND METHODS OF CONTROL OF PINE ROOT-COLLAR BARK WEEVIL

Pine root-collar bark weevil (Hylobitelus sp. ) is widespread in Yunnan province. The larvae mainly infest young and middle forests of Pinus yunnanensis, P. kesiya and P. armandi by boring the embium and the phloem at root-collar of the trees.The slight injury makes the needles turn to yellow and brown, and the serious makes trees grow slow and even die. Hylobitelus sp. requires 2 years to complete 1 generation,and the adults and larvae of 5- 7 instars live through winter.The emergence begins in the middle of August, and the adults, through winter twice, live two years. The mating actions occur in all the adult period, but the adults do not lay eggs in this year themselves emerged. Larval stage continues for 10-14 months, most larvae are 7-8 instars. The pupation begins in late Junly, and the popal stage is about 27 days. Because the population density of this weevil is quite low, and the period in which the matural lavae,through pupating and emerging, become adults lasts,more than two months, and their instars are quite regular, they can be easily destroyed by hand during the period from late August to, the middle of September.