RELEASE, ESTABLISHMENT AND SPREAD OF ASIAN NATURAL ENEMIES OF EUONYMUS SCALE (HOMOPTERA, DIASPIDIDAE) IN NEW-ENGLAND

Between 1990 and 1995, the USDA/APHIS National Biological Control Labo ratory in Niles, MI, Texas A&M University, and the University of Massa chusetts conducted a biological control introduction program against t he Asian diaspidid scale insect Unaspis euonymi (Comstock), a pest of woody landscape plants. Two species of predators (Chilocorus huwanae S ilvestri, Coleop.: Coccinellidae and Cybocephalus sp. nr. nipponicus E nrody-Younga, Coleop.: Cybocephalidae) and three aphelinid parasitoids (Encarsia sp. nr. diaspidicola [Silvestri], Coccobius sp. nr. fulvus [Compere et Annecke], and Aphytis sp.) were collected near Beijing, Ch ina and released in southern New England. We report establishment of C . kuwanae, C. sp. nr. nipponicus and Coccobius sp. nr. fulvus in Massa chusetts. Chilocorus huwanae has spread throughout southern New Englan d and the proportion of euonymus shrubs in landscape-level surveys bea ring C. kuwanae stages was positively related to scale density, with t he coccinellid present on 1.1%, 6.3%, 12.5%, and 26.3% of shrubs whose scale populations were classified as none, light, medium, and heavy, among 4843 plants examined from 1992-1994 in Massachusetts, Connecticu t, and Rhode Island. Cybocephalus sp. nr. nipponicus and C, sp. nr. fu lvus, while established at some release sites, have been observed to s pread to new locations in only one and two instances, respectively. En carsia sp. nr. diaspidicola was recovered at some release locations, b ut establishment is uncertain. No recoveries were made of the Aphytis sp. parasitoid, but this species was released later than the other spe cies and further recovery efforts are needed.