Attachment 1 – Suppression of Hemlock Wooly Adelgid - June 2009 Daniel Boone National Forest

Biology of the Hemlock Wooly Adelgid A fully grown adult of the hemlock woolly nymphs remain at this site (where needles adelgid is only about the size of a period on attach to twigs) until maturity. In New this printed page. However, this is Jersey, nymphs enter a hibernation stage easily recognized during most of the year by (aestivate) in late summer before resuming the presence of a dry, white woolly feeding in the fall. By October, nymphs substance on the young twigs. This "wool" begin covering themselves with white is associated with all stages of the adelgid, cottony wax, initially secreting it along the but it is most abundant and conspicuous outer edge of their bodies like white fringe. during spring when egg masses are present. There is one spring generation a year plus a They can be observed at the base of partial fall generation. (Note: The black individual needles, covering themselves nymphs are exposed on new growth for a with fluffy white, cottony wax. This wax long period, from June to October, before often remains firmly attached to hemlock beginning to secrete their white protective branches long after the insect dies. wax. They are very susceptible to control Fig 1. feeding on tactics at this time.) eastern hemlock Biology of HWA predatory Predatory beetles are biocontrol agents that have been thoroughly evaluated, and that meet USDA biological and environmental risk assessment criteria for release. Currently, these beetles are Sasajiscymnus tsugae (formerly Pseudoscymnus tsugae), nigrinus, Scymnus sinuanodulus, and Scymnus ningshanensis. The predatory Sasajiscymnus tsugae is a native of Japan as is the HWA. Dr. Mark McClure of the Connecticut All Hemlock Woolly Adelgid are female. Agricultural Experiment Station discovered Brownish orange eggs are laid under the the beetle in 1992 while in Japan hunting for cottony wax and hatch during an extended HWA predators. It is a tiny black lady period from February through June. Eggs beetle about the size of a poppy seed. It was are dispersed from tree to tree throughout studied in a laboratory setting for several the spring, via wind, birds, and other years and determined to have excellent . potential as a biological control agent for HWA. It specifically attacks adelgids and Newly hatched woolly adelgids (immature both the larvae and adult beetles feed crawlers) are black, oval, and flat. They voraciously on all life stages of HWA. Its emerge from the cottony egg mass as the life cycle is well synchronized with that of new hemlock growth expands in May and the adelgid, and it completes at least two June. The tiny immature crawlers can only generations each year in the field. The be seen with a hand lens because they are beetle does not show undesirable traits that barely visible to the naked eye. would cause it to be a nuisance or otherwise Crawlers migrate to new growth, molt, lose poor candidate for release. The USDA their legs, and settle down at the base of a granted a permit for its release in 1995. needle and begin to feed. These immature There have been numerous releases across 1 of 2 Attachment 1 – Suppression of Hemlock Wooly Adelgid - June 2009 Daniel Boone National Forest

the eastern US, including experimental developed at Virginia Tech, Clemson, and releases on the other southern Appalachian the University of Tennessee. national forests. New rearing facilities have Information about Insecticides made the beetles somewhat more available for mass releases. Imidacloprid is a widely used systemic insecticide with applications ranging from Scymnus sinuanodulus and Scymnus agricultural food production to flea control ningshanensis are also small lady beetles on pets. Unlike common aerosol that were imported from China in the late insecticides that may injure or kill non-target 1990’s (fig.2). They have been thoroughly species, systemics are “taken up” by the host studied and have certain lifecycle attributes plant and kill only those that feed that may complement those of P. tsugae in upon the host. Imidacloprid is classified as a the fight against HWA. These beetles have neonicotinoid (nicotine-like) pesticide with quite limited availability now but that should remarkably high insecticidal activity against improve with the development of mass plant-sap-sucking insects, such as the rearing capabilities. Hemlock Wooly Adelgid. Figure 3 depicts Fig 2. Scymnus beetles feeding on hemlock woolly imidacloprid being injected into the soil at adelgid the base of an infested hemlock. Fig 3. Soil injection with Imidacloprid

Laricobius nigrinus is a tiny derodontid beetle that can be found feeding on HWA in Washington, Oregon, Idaho, and British Columbia. Field studies in British Columbia Insecticidal soaps and horticultural oils kill and investigations in the laboratory have adelgids by smothering them. These soaps revealed that L. nigrinus possesses many and oils are applied as foliar sprays and to important qualities of a successful biological be most effective must be applied to the control agent. Laricobius nigrinus feeds entire plant surface. Therefore, they have selectively on HWA and is unable to limited usefulness for large trees with large complete development while feeding on any crown surfaces. These chemicals could be other insect. L. nigrinus will likely be a lethal to insects other than adelgids on or complementary component of a predator near the tree when it is sprayed. In addition, complex because, being a winter-active soaps and oils have limited long-term predator, it is unlikely to compete with other usefulness because they have no residual predators that become active later in the effect. spring. Mass-rearing methods are being

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