Parasitoids Reared From Predators of Hemlock Woolly Adelgid (Hemiptera: Adelgidae), and the Hymenopterous Parasitoid Community on Western Hemlock in the Pacific Northwest

Abstract

In western North America, infestations of the hemlock woolly adelgid, Adelges tsugae Annand (Hemiptera: Adelgidae), are common on orchard, ornamental, and roadside western hemlock, Tsuga heterophylla (Raf.) Sargent. However, these infestations rarely cause T. heterophylla mortality. Host tolerance and presence of endemic predators may be contributing to the relatively low levels of injury to T. heterophylla caused by A. tsugae. Field surveys of the arthropod community associated with A. tsugae infestations on 116 T. heterophylla at 16 sites in Oregon and Washington were conducted every 4-6 wk from January 2005 through November 2006. Fourteen uninfested T. heterophylla were also surveyed across 5 of the 16 sites. Immature A. tsugae predators collected in the field were brought to the laboratory for rearing. Eight species of hymenopterous parasitoids were reared from pupae of predators of A. tsugae in the laboratory. Two Pachyneuron spp. (Pteromalidae) and a Melanips sp. (Figitidae) were reared from Leucopis spp. (Diptera: Chamaemyiidae) puparia. Syrphoctonus pallipes (Gravenhorst) (Ichneumonidae), Woldstedtius flavolineatus (Gravenhorst) (Ichneumonidae), Syrphophagus sp. (Encyrtidae), and Pachyneuron albutius Walker were reared from Syrphidae (Diptera) puparia. A Helorus sp. (Heloridae) was reared from a Chrysoperla sp. (Neuroptera: Chrysopidae) cocoon. Laboratory rearing did not show any direct association between parasitoids and A. tsugae. In the field survey, a total of 509 adult parasitic Hymenoptera representing 19 families and at least 57 genera were collected from T. heterophylla. Nonparametric analysis of community structure showed Pachyneuron spp. were strongly correlated to abundance of their Leucopis spp. hosts and to A. tsugae population score in the field. The possible impact of parasitism on Leucopis spp., potential A. tsugae biological control candidates for the eastern United States, is discussed.

Hemlock Woolly Adelgid (Hemiptera: Adelgidae) Management in Forest, Landscape, and Nursery Production

“…Biocontrol predators that are to some degree being currently assessed include: Sasajiscymnus tsugae (Sasaji and McClure) (Coleoptera: Coccinellidae), Laricobius nigrinus Fender (Coleoptera: Derodontidae), Laricobius osakensis Montgomery (Coleoptera: Derodontidae), Scymnus coniferarum (Crotch) (Coleoptera: Coccinellidae), Scymnus sinuanodulus Yu and Yao (Coleoptera: Coccinellidae), Leucopis argenticollis (Zetterstedt) (Diptera: Chamaemyiidae), and Leucopis piniperda (Malloch) (Cheah et al. 2004, Kohler et al. 2008, Darr and Salom 2014, Mooneyham and Salom 2014, USDA Forest Service 2015).…”

A Little Bug with a Big Bite: Impact of Hemlock Woolly Adelgid Infestations on Forest Ecosystems in the Eastern USA and Potential Control Strategies

“…Up to 50 species of generalist and specialist predators of HWA have been identified in Japan or eastern Asia [119]. Several predators have been tested for biological control potential since 1992 [17,90,119,120,121,122,123,124,125,126,127,128,129,130]. For example, the lady beetle Sasajiscymnus tsugae , a native predator of HWA in Japan was initially imported to and studied in New Jersey.…”

Factors Affecting Establishment and Recovery of <I>Sasajiscymnus tsugae</I> (Coleoptera: Coccinellidae), an Introduced Predator of Hemlock Woolly Adelgid (Hemiptera: Adelgidae) on Eastern Hemlock (Pinales: Pinaceae)

“…Furthermore, 55 predatory species representing 14 families were recovered from western hemlock, Tsuga heterophylla (RaÞnesque-Schmaltz) Sargent, in the western United States. The abundances of larval Laricobius spp., adult Laricobius nigrinus Fender (Coleoptera: Derodontidae), and adult Leucopis argenticollis Zetterstedt (Diptera: Chamaemyiidae) on western hemlock were found to be positively correlated to hemlock woolly adelgid, and considered to be hemlock woolly adelgid specialist predators (Kohler et al 2008). In the eastern United States, Ͼ60 generalist predatory species belonging to 21 families in Þve orders have been documented from eastern hemlock (Wallace andHain 2000, Buck et al 2005).…”