|Zhu, Yu Cheng|
Submitted to: Annals of the Entomological Society of America
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/22/1998
Publication Date: N/A
Interpretive Summary: Efforts to control insect pests with biological control agents are sometimes hampered by our inability to tell very closely related species of these agents apart. We cannot evaluate the effectiveness of a biological control program against the multi-million dollar a year wheat pest complex of cereal aphids, including the Russian wheat aphid, because a group of microwasps imported and released to attack them are extremely difficult to tell apart. We attempted to solve this problem through use of the polymerase chain reaction, a powerful DNA fingerprinting technique. The method we developed is extremely sensitive and distinguishes all three species, as well as two geographic strains of one of the species. It can also detect the immature parasitic form of the wasp inside the aphid host.
Technical Abstract: Ribosomal DNA sequences for the internal transcribed spacer 2 (ITS2) were cloned and sequenced from Aphelinus albipodus, A. varipes, and two strains of A. asychis, endoparasitoids that were released against the Russian wheat aphid (RWA), Diuraphis noxia. The polymerase chain reaction using primers designed on the basis of these rDNA sequences, followed by agarose gel electrophoresis, successfully distinguishes all four Aphelinus populations from each other and from the RWA and another economically important cereal aphid, the greenbug (GB), Schizaphis graminum. Two additional strains of A. asychis and a post-release population of A. albipodus are also correctly identified to species with these primers. Using this technique, A. asychis DNA is detectable in a parasitized RWA 24 h following parasitization. The sensitivity is 1/1,000 adult wasp DNA equivalent.