Submitted to: Biological Control
Publication Type: Peer reviewed journal
Publication Acceptance Date: 9/13/2002
Publication Date: 4/1/2003
Citation: Unruh, T.R., Short, R.E., Herard, F., Chen, K., Hopper, K.R., Pemberton, R.W., Lee, J.H., Ertle, L.R., Swan, K.S., Fuester, R.W. 2003. Inroduction and establishment of parasitoids for the biological control of the apple ermine moth, Yponomeuta malinellus (Lepidoptera: Yponomeutidae), in the Pacific Northwest. Biological Control. 28:332-345. Interpretive Summary: Insect predators and parasites are key agents in the control of insect pests in many crops and these agents, especially parasites, are often specialized to attach a specific host species. In the 1980s the apple ermine moth, a pest whose caterpillars eat apple foliage and fruits in Eurasia, colonized and became broadly established in the Pacific Northwest. Because this pest arrived without specialized parasites that control it in Eurasia, the USDA-ARS initiated a multi-laboratory program to find, collect, introduce and hopefully establish these beneficial insect parasites to control the pest in Washington and Oregon. From 1988-1993 over 100,000 parasitic wasp and flies were introduced into Washington, comprising 4 distinct species. Of these, 2 species have established, and one, the wasp Ageniaspis fuscicollis, produces significant parasitism of the ermine moth in Washington. The ermine moth has declined dramatically from 1989 through 1996, and it now exists at non-economic levels in Washington. The introduced agents together with predators native to Washington are responsible for this decline.
Technical Abstract: Four parasitoids were imported from five countries in Eurasia and released in northwestern Washington to control the Apple Ermine moth. Yponomeuta malinellus Zeller, which colonized the Northwest around 1981. From 1988 to 1991, 95,474 Ageniaspis fuscicollis (Dalman) (Hymenoptera: Encyrtidae) from France, China, Korea and Russia were released in Washington. One or more geographic races of A. fuscicollis established and dramatically increased parasitism rates of Y. malinellus between 1989 and 1994 at 22 monitored sites. Between 1989-1991, a total of 1,813 Herpestomus bunnicornis (Gravenhorst) (Hymenoptera: Ichneumonidae) from France, Korea and Japan were released; a total of 26 wasps were recovered between 1994 and 1995. From 1989 to 1991, 2,647 Diadegma armillata (Gravenhorst) (Hymenoptera: Ichneumonidae) from France were released. D. armillata was recovered at one site in 1991 two months following release, but no other recoveries have been made. A total of 8,274 Eurystheae scutellaris (Rob. Desv.) (Diptera: Tachinidae) from France were released in 1989 to 1991; this fly has not been recovered. Strong increases in parasitism by A. fuscicollis were contemporaneous with a sharp decline of Y. malinellus populations in 1989-1995 suggesting this wasp may have helped cause the pest's decline and should help maintain low densities in the future.