Department of Entomology, University of Georgia, 1109 Experiment St., Griffin, GA 30223-1797, USA.
J Econ Entomol. 2011 Jun;104(3):868-78. doi: 10.1603/ec10145.
Healthy hemlock trees, Tsuga canadensis (L.) Carrière, and hemlock woolly adelgid, Adelges tsugae Annand (Hemiptera: Adelgidae), populations should favor retention and population growth of adelgid predators such as Laricobius nigrinus Fender (Coleoptera: Derodontidae) and Sasajiscymnus tsugae (Sasaji & McClure) (Coleoptera: Coccinellidae). Eastern hemlock trees between 15 and 38 cm diameter at breast height (dbh) were treated with 0, 10, or 25% of 1.5 g imidacloprid (Merit 75 WP) per 2.5 cm dbh and were either fertilized or not, in a 3 by 2 factorial design. After 2 yr, imidacloprid reduced the numbers of ovisacs and eggs found on trees in a dosage-dependent manner, while enhancing tree growth parameters such as new shoots or needles and the length of new shoots. Fertilized trees had greater adelgid fecundity, which was positively correlated with total foliar N in both winter generations. In February 2009 (27 mo after imidacloprid treatment), higher imidacloprid dosages to unfertilized trees resulted in reduced adelgid fecundity. Concentrations of N, P, and K were higher in the foliage of trees treated with insecticide, whereas foliar aluminum concentrations were consistently lower in trees with higher insecticide dosages. Trees treated with low rates of imidacloprid were healthier than untreated trees, but only trees treated with the 0.1 x dosage had sufficient adelgids to possibly sustain predators over extended periods.
健康的铁杉树和铁杉羊毛衣虫，Adelges tsugae Annand（半翅目：衣虫科）种群应有利于保留和衣虫捕食者的种群增长，如拉氏黑缘步甲和 Sasajiscymnus tsugae（Sasaji 和 McClure）（鞘翅目：瓢虫科）。胸径（dbh）为 15 至 38 厘米的东方铁杉树，采用 0、10 或 25%的 1.5 克氯吡虫啉（Merit 75 WP）/2.5 厘米 dbh 进行处理，同时进行施肥或不施肥，采用 3 乘 2 析因设计。两年后，氯吡虫啉以剂量依赖的方式减少了在树上发现的卵囊和卵的数量，同时增强了树木生长参数，如新梢或针叶的长度和新梢的长度。施肥的树木具有更高的衣虫繁殖力，这与冬季两代中总叶氮呈正相关。在 2009 年 2 月（氯吡虫啉处理后 27 个月），未施肥树木较高的氯吡虫啉剂量导致衣虫繁殖力降低。处理过杀虫剂的树木叶片中的氮、磷和钾浓度较高，而叶片中的铝浓度在高剂量杀虫剂处理的树木中始终较低。用低剂量氯吡虫啉处理的树木比未处理的树木更健康，但只有用 0.1x 剂量处理的树木才有足够的衣虫，可能在较长时间内维持捕食者。
