Montgomery Michael E, Bentz S E, Olsen Richard T
USDA-Forest Service, Northern Research Station, Hamden, CT 06514, USA.
J Econ Entomol. 2009 Jun;102(3):1247-54. doi: 10.1603/029.102.0351.
Hemlock (Tsuga) species and hybrids were evaluated for resistance to the hemlock woolly adelgid, Adelges tsugae Annand (Hemiptera: Adelgidae). The adelgid was accidentally introduced from Asia to the eastern United States, where it is causing widespread mortality of the native hemlocks, Tsuga canadensis (L.) Carrière and Tsuga caroliniana Engelm. These two native species plus the Asian species Tsuga chinensis (Franch.) E. Pritz and T. dumosa (D.Don) Eichler and Tsuga sieboldii Carrière, and the hybrids T. chinensis x T. caroliniana and T. chinensis x T. sieboldii, were artificially infested with the crawler stage of A. tsugae in the early spring 2006 and 2007. After 8 or 9 wk-when the spring (progrediens) generation would be mature--counts were made of the adelgid. In both years, the density of A. tsugae was highest on T. canadensis, T. caroliniana, and T. sieboldii; lowest on T. chinensis; and intermediate on the hybrids. On T. chinensis and the T. chinensis hybrids, fewer adelgids settled, fewer of the settled adelgids survived, and the surviving adelgids grew slower. Thus, the nature of the host resistance is both nonpreference (antixenosis) and adverse effects on biology (antibiosis). Tree growth (height) was associated with resistance, but no association was found between time of budbreak and resistance that was independent of the taxa. Many of the hybrids grow well, have attractive form, and are promising as resistant landscape alternatives for the native hemlocks.
对铁杉属（Tsuga）物种及其杂种进行了抗铁杉球蚜（Adelges tsugae Annand，半翅目：球蚜科）的评估。该球蚜意外地从亚洲传入美国东部，在那里它导致当地铁杉，即加拿大铁杉（Tsuga canadensis (L.) Carrière）和卡罗来纳铁杉（Tsuga caroliniana Engelm）大量死亡。这两个本地物种加上亚洲物种中国铁杉（Tsuga chinensis (Franch.) E. Pritz）、高山铁杉（T. dumosa (D.Don) Eichler）、日本铁杉（Tsuga sieboldii Carrière），以及杂种中国铁杉×卡罗来纳铁杉和中国铁杉×日本铁杉，于2006年和2007年早春人工接种了铁杉球蚜的若虫阶段。8或9周后（此时春季（进展型）世代将成熟），对球蚜进行计数。在这两年中，铁杉球蚜的密度在加拿大铁杉、卡罗来纳铁杉和日本铁杉上最高；在中国铁杉上最低；在杂种上居中。在中国铁杉及其杂种上，定居的球蚜较少，定居的球蚜存活下来的较少，并且存活的球蚜生长较慢。因此，寄主抗性的性质既是不选择性（排趋性）又是对生物学的不利影响（抗生性）。树木生长（高度）与抗性相关，但未发现芽萌动时间与抗性之间存在独立于分类群的关联。许多杂种生长良好，形态美观，有望作为本地铁杉的抗性景观替代树种。
