Submitted to: Southwestern Entomologist
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/1/1998
Publication Date: N/A
Interpretive Summary: Aphelinus albipodus and A. asychis are parasitoids that were imported into the United States for classical biological control of the Russian wheat aphid. Geographic variation in biology and ecology can affect the ability of a parasitoid to establish and control a pest in the new environment into which it is released. This study was undertaken to determine the ability of fgeographic strains of these parasitoids to attack common aphids in the areas of the United States into which they were targeted for release. The purpose was to determine if host differences existed between the strains that could influence their effectiveness in biological control. Strains of both species exhibited minor differences in the ability to parasitize 16 common aphid species, and strains of A. albipodus collected from geographically proximate locations in Asia showed more similarity in their ability to parasitize the aphids than strains from distant locations. Overall, differences in the ability of strains of both species to parasitize the 16 aphids were small. The practical significance is that there should be no barriers to inhibit the establishment and effectiveness of the parasitoids related to their ability to parasitize alternate hosts at times when Russian wheat aphids are absent or at very low density. This could permit the parasitoids to persist in the new environment and become effective biocontrol agents.
Technical Abstract: Aphelinus asychis (Walker) and Aphelinus albipodus Hayat and Fatima obtained from locations in Asia and Africa (hereafter referred to as strains) were tested in the laboratory for their ability to parasitize 16 aphid species. Aphelinus asychis from China and Morocco developed to the mummy stage in 15 of the 16 aphid species, while a strain from Kazakhstan developed to the mummy stage in 13 species. A nominal rating system was used to quantify the extent of mummy formation for strains. Ratings were correlated for strains from China and Kazakhstan and for strains from China and Morocco, but not for the strains from Kazakhstan and Morocco. Although there were differences among strains in mummy formation ratings and percent adult emergence, strains from proximate geographic locations were no more similar with respect to these characteristics than strains from widely separated locations. Aphelinus albipodus strains were obtained from three locations in China (Altai, Pingluo, and Urumqi) and Cacausus. The strains from Altai, Urumqui, Pingluo, and Cacausus parasitized 13, 12, 11, and 9 species, respectively. There was no difference in the adult emergence rate among strains of A. albipodus. Mummy formation ratings differed among strains. Correlations for mummy formation ratings were greater for geographically proximate strains than for strains from widely separated locations.