松墨天牛在秦巴林区不同寄主上的危害规律

松墨天牛Monochamus alternatus是次期性蛀干害虫,也是松材线虫病的主要传播媒介,廓清该害虫在秦巴林区不同寄主上的危害程度和发生规律,对于控制松材线虫病的扩散蔓延具有重要意义.本研究对秦巴林区遭受松材线虫病严重危害的3种主要松树(油松Pinus tabuliformis、华山松P.armandii和马尾松P.massoniana)进行了冬季疫木野外解析,并在统计不同胸径、不同高度疫木树干上松墨天牛侵入孔和幼虫数量的基础上,采用聚集度指标分析方法,对该害虫在不同寄主上的危害差异进行了比较研究.结果表明,松墨天牛在3种寄主上的危害程度具有显著差异,以华山松受害最重,其次分别为马尾松和油松;越冬幼虫在油松上主要危害皮下1～2 cm的边材;在华山松和马尾松上危害比较多样,以髓心部位受害最重,其后依次为心材、边材和树皮;在油松和华山松上,松墨天牛主要在树干7m以下部分危害,而在马尾松上主要危害树干7m以上部分,且虫口数量均与寄主胸径呈显著正相关.松墨天牛侵入孔和越冬幼虫在不同寄主树干上均呈聚集性分布.本研究揭示了松墨天牛在秦巴林区3种主要寄主上的危害规律,对于进一步开展大尺度地理范围松墨天牛的寄主选择性及危害规律研究提供了基础信息,也为秦巴林区松墨天牛的有效防治和松材线虫病的蔓延控制提供了新的重要信息.

The damage of Monochamus alternatus on different host pine species in Qinling-Daba Mountains

Monochamus alternatus, a secondary longhorned borer, is the main vector of the pine nematode disease. Clarifying the damage and regularity of outbreak of this pest in different host plants in the Qinling-Daba Mountains is particularly important to control the spread of pine nematode disease. The number of entrance holes and the population of overwintering larvae of M. alternatus in the trunk of three pine species (Pinus tabuliformis, P. armandii and P. massoniana) were investigated, and their correlations to the diameter at breast height (DBH) and the height of damaged site on the trunk were analyzed using the aggregation index analysis method, aiming to reveal the damage difference of M. alternatus in different tree species. The results showed that the damage degree of this pest to the three pine tree species were significantly different, among which the damage to P. armandii was most severe, followed by that to P. massoniana and P. tabuliformis subsequently. The overwintering larvae of M. alternatus damage P. tabuliformis mainly in the sapwood about 1~2 cm underneath the bark. Whereas, in both P. armandii and P. massoniana the overwintering larvae damage the pith most severely, followed by the heartwood, sapwood and the bark subsequently. In P. tabuliformis and P. armandii, the larvae of M. alternatus mainly distributed in the trunk where the height of the damaged site was usually less than 7 m above the ground. However, the larvae damage P. massoniana mainly in the trunk where the height of the damaged site was usually higher than 7 m above the ground. The number of entrance holes and the number of overwintering larvae were significantly, positively correlated with DBH. The entrance holes and overwintering larvae of M. alternatus in different pine trees were aggregated. The damage characteristic of M. alternatus to different hosts in the Qinling-Daba Mountains provided information to future studies of host selection and damage mechanism of this pest in large-scale geographic patterns, which were helpful to the control of this vector sawyer beetle and the related pine wilt disease in the Qinling-Daba Mountains.