Submitted to: Biological Control
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/9/2004
Publication Date: 11/20/2004
Citation: Wu, Z., Hopper, K.R., O'Neil, R., Voegtlin, D., Prokrym, D., Heimpel, G.E. 2004. Reproductive compatibility and genetic variation between two strains of Aphelinus albipodus (Hymenoptera: Aphelinidae), a parasitoid of the soybean aphid, Aphis Glycines (Homoptera: Aphididae). Biological Control. 31(3): 311-319. Interpretive Summary: Soybean aphid is a major pest of soybean which has recently invaded the United States, putting whole regions of soybean production at risk. As part of an effort to find predators and parasites of this aphid that might be useful for its control, we compared two populations of an aphid parasite, one already established in the US for control of Russian wheat aphid and another found in Japan on soybean aphid and proposed for introduction to control this pest. We found that they were partially reproductively incompatible and that the one from Japan did not parasitize Russian wheat aphid. The one already established in the US on Russian wheat would parasitize soybean aphid. Therefore, the latter parasitoid is being released to control soybean aphid because it does not involve introduction of a new, exotic species, which might have non-target impacts.
Technical Abstract: APHELINUS ALBIPODUS Hayat and Fatima is a potential biological control agent of the soybean aphid, APHIS GLYCINES Matsumura, which is a newly introduced soybean insect pest in the United States. We compared the reproductive compatibility and molecular genetic variation between two geographic strains of A. ALBIPODUS. One of these strains had been collected from soybean aphids in Japan and the other from cereal aphids in Eurasia and established on Russian wheat aphid, DIURAPHIS NOXIA (Mordvilko) in the western U.S. We present the results of crossing experiments between the two strains, genetic differentiation based on RAPD-PCR markers, rDNA ITS1 & 2 gene sequences, and detection and frequency of WOLBACHIA in the two strains using PCR amplification of the wsp gene. We found no reduction in the production of females in reciprocal crosses between strains, but a reduction in fecundity when F1 females were backcrossed to males from each source. The two strains differ by 3.4% in the rDNA ITS1 sequence and by presence/absence of a RAPD-PCR marker, but their rDNA ITS2 sequences are identical. Restriction enzyme analysis can be used to separate the strains by differential digestion of the ITS1 PCR product. WOLBACHIA was present in 100% of males and females of both strains of A. ALBIPODUS.