Submitted to: Southwestern Entomologist
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: January 1, 2001
Publication Date: N/A
Interpretive Summary: In 1988, a consortium of scientists was organized to implement a classical biological control program for the recently introduced Russian wheat aphid, Diuraphis noxia. Exotic natural enemies of D. noxia were imported from its reputed aboriginal home of Eurasia and released in the wheat and barley producing areas of the western United States. From 1988 through 1997, over 11.8 million individuals of 11 Hymenopterous parasitoid species, comprisin more than 80 geographic strains, collected from 25 different countries, were released. Within this framework, the USDA-ARS, Plant Science Research Laboratory in collaboration with USDA-APHIS, Colorado State Agricultural Experiment Station, and the Colorado Department of Agriculture conducted an intensive biological control release program from 1991 through 1993 in an attempt to establish exotic D. noxia natural enemies in small grain agroecosystems of eastern Colorado. Seven species, Aphelinus albipodus, Aphelinus asychis, Aphelinus varipes, Aphidius colemani, Aphidius matricariae, Diaeretiella rapae, and Ephedrus plagiator, were introduced into infested wheat fields. Three years later, A. albipodus, A. asychis, and A. varipes, and D. rapae have become established over a 6-state region. A. albipodus, A. varipes, and D. rapae were recovered from greenbugs on sorghum. A. albipodus and D. rapae successfully parasitized D. noxia on non-cultivated grasses that serve as aphid oversummering hosts. Summaries of parasitoid recoveries and their host and plant species associations are discussed. In an IPM context, the establishment of natural enemies is important because they have no economic cost, are highly compatible with plant resistance, and can contribute considerably to the overall reduction in the reliance of insecticides to control aphid cereal pests.
Technical Abstract: From 1991 through 1993 exotic parasitoids of the Russian wheat aphid, Diuraphis noxia (Mordvilko), were released in eastern Colorado in an attempt to establish natural enemies for biological control in small grain agroecosystems. Seven species, Aphelinus albipodus Hayat and Fatima, Aphelinus asychis Walker, Aphelinus varipes (Forester), Aphidius colemani (Viereck), Aphidius matricariae Haliday, Diaeretiella rapae (M'Intosh), an Ephedrus plagiator (Nees), from D. noxia's aboriginal home of Eurasia were introduced into aphid-infested wheat fields. Three years later, three aphelinid species, A. albipodus, A. asychis, and A. varipes, and a putative Chinese strain of D. rapae, have become established over a six-state region. A. albipodus, A. varipes, and D. rapae were recovered from greenbugs, Schizaphis graminum (Rondani), on sorghum, Sorghum bicolor (L.) Moench. A. albipodus and D. rapae successfully parasitized D. noxia on several non-cultivated grasses that serve as over-summering hosts. Summaries of parasitoid recoveries and their host and plant species associations are discussed.