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Abstract
Hemlock woolly adelgid,
Adelges tsugae Annand (Homoptera: Adelgidae), has two generations/year that feed and reproduce on hemlock,
Tsugae spp. The spring generation, present from March to June, is called progrediens. The next generation, present from June until the following March, is called sistens (McClure 1987, Gray and Salom 1996). In June, after sistens eggs hatch, they settle at the base of needles and immediately go into an aestival diapause that lasts until October, a duration of 4 months. The occurrence of aestival diapause in HWA sistens is a barrier when trying to continuously rear its predators.
Pseudoscymnus tsugae Sasaji and McClure (Coleoptera: Coccinellidae), a biological control agent brought in from Japan (Cheah and McClure 1998), do not produce eggs when feeding on diapausing sistens (Bob Chianese, N.J. Dept. of Agric., personal communication). Year-round production of
P. tsugae could be achieved if we could prevent HWA from going into diapause. The goals of our research were to: 1. determine if diapause in HWA is obligative or facultative and 2. if facultative, determine what conditions are optimal for continuously rearing HWA.
Parent Publication
Citation
Salom, Scott M.; Mays, Warren T.; Neal, John; Sharov, Alexei. 2000. Evaluation of aestival diapause in hemlock woolly adelgid. In: McManus, Katherine A.; Shields, Kathleen S.; Souto, Dennis R., eds. Proceedings: Symposium on sustainable management of hemlock ecosystems in eastern North America. Gen. Tech. Rep. NE-267. Newtown Square, PA: U.S. Department of Agriculture, Forest Service, Northeastern Forest Experiment Station: 200.
