云南横坑切梢小蠹生物学研究

On the bionomics of Tomicus minor (Hartig) (Coleoptera: Scolytidae) in Yunnan Province

横坑切梢小蠹Tomicusminor (Hartig)是云南松PinusyunnanensisFranchet的主要次期性害虫之一。 1980年以来 ,该虫与纵坑切梢小蠹T .piniperda(L .)一起在中国西南部大量发生 ,导致数十万公顷云南松林受害。本文报道了横坑切梢小蠹在云南地区的生活史、生长、发育、繁殖等生物学特征。横坑切梢小蠹年生活史为一代 ,前后两代在冬春季有部分重叠。成虫羽化于4月下旬开始陆续 ,5月下旬结束。成虫羽化后即飞到树冠上蛀食枝梢 ,直到 11月发育成熟 ,开始繁殖。在此期间 ,每头成虫可以蛀食 4～ 6个枝梢。横坑切梢小蠹在云南没有越冬习性。繁殖期从 11月至次年 3月。成虫主要在已经受到纵坑切梢小蠹危害的树木的中、下部产卵。繁殖期较纵坑切梢小蠹约迟 1周。由于横坑切梢小蠹从枝梢到树干对云南松持续危害 ,对树木的危害性较在其它地区更为严重。横坑切梢小蠹利用受到纵坑切梢小蠹蛀害的树木繁殖产卵 ,加强了蠹虫对云南松树的危害 ,加速了受害树木的死亡进程。横坑切梢小蠹的上述生物生态学特征是该虫对云南松造成严重危害的重要原因。从横坑切梢小蠹虫体和虫坑中检测到伴生真菌云南半帚孢Leptographiumyunnanensis。横坑切梢小蠹对该菌的带菌率在蛀梢期为11 5 % ;在蛀干中期约为 10 %～ 2 6 %。

Tomicus minor (Hartig) is one of major secondary pest insects of the Yunnan pine, Pinus yunnanensis Franchet. From the 1980s, the pine shoot beetle together with T. piniperda (L.)occurred in abundance in Yunnan, southwestern China, causing several hundred thousand ha Yunnan pine forests seriously damaged. The biology and behavior of the beetle were reported here, including its life cycle, development, shoot feeding, trunk attacking and reproduction. T. minor completed one generation a year, with consecutive two generations overlapping in winter and spring. Adults started to emerge in the mid April and ended in the late May. After emerged, T. minor flied to the crown and fed the shoots in nearby trees. The shoot feeding period lasted until the late November when adults got matured. Adults bored 4-6 shoots in total during the shoot feeding. T. minor flied to the trunk of Yunnan pine tree for reproduction after matured. The reproduction period lasted from the late November to March. T. minor mostly bred in the trees already attacked by T. piniperda. The attacking normally occurred one week later than T. piniperda, and focused on the mid and lower trunks. Since the beetle did its damages from the shoots to trunks, the damages to the host trees seemed more serious than that in other districts. Meanwhile, T. minor breeding in the trees attacked by T. piniperda would decrease the tree resistance, and so accelerate the host tree dying. The beetles bionomics and behavior particularly showed in Yunnan were supposed to the major reason that the beetle occurred massively and caused serious damages to the Yunnan pine trees in southwestern China. A fungus Leptographium yunnanensis was detected from T. minor and its galleries, which was regarded as the fungus associated with T. minor. Frequencies of the beetle carrying the fungus were 11.5% in shoot feeding period, and 10%-26% in trunk attacking.