Journal of Economic Entomology (2005) 98, 217-221

Douglas B. Jones, Kristopher L. Giles, Yi Chen and Kevin A. Shufran (2005)
Estimation of hymenopteran parasitism in cereal aphids by using molecular markers
Journal of Economic Entomology 98 (1), 217-221
Abstract: Polymerase chain reaction (PCR) primers were designed and tested for identification of immature parasitoids in small grain cereal aphids and for estimation of parasitism rates. PCR technique was evaluated for 1) greenhouse-reared greenbugs, Schizaphis graminum (Rondani), parasitized by Lysiphlebus testaceipes Cresson and 2) aphids collected from winter wheat fields in Caddo County, Oklahoma. For greenhouse samples, parasitism frequencies for greenbugs examined by PCR at 0, 24, and 48 h after removal of L. testaceipes parasitoids were compared with parasitism frequencies as determined by greenbug dissection. PCR was unable to detect parasitism in greenbugs at 0 and 24 h postparasitism, but it was able to detect parasitoids 48 h after parasitoid removal at frequencies that were not significantly different from dissected samples. Field-collected samples were analyzed by rearing 25 aphids from each sample and by comparing parasitoid frequencies of mummies developed and PCR performed on another 50 aphids. Aphid samples included corn leaf aphids, Rhopalosiphum maidis (Fitch); bird cherry-oat aphids, Rhopalosiphum padi (L.); English grain aphids, Sitobion avenae (F.); and greenbugs. Mummies were isolated until adult emergence, whereupon each parasitoid was identified to species (L. testaceipes was the only parasitoid species found). Parasitism detection frequencies for PCR also were not statistically different from parasitism frequencies of reared aphids. These results indicate that PCR is a useful tool for providing accurate estimates of parasitism rates and especially for identification of immature parasitoids to species.
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Database assignments for author(s): Douglas B. Jones, Yi Chen

Research topic(s) for pests/diseases/weeds:
biocontrol - natural enemies
Research topic(s) for beneficials or antagonists:
surveys/distribution/isolation
identification/taxonomy

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Rhopalosiphum maidis	Wheat (Triticum)	U.S.A. (mid S)
	Sitobion avenae	Wheat (Triticum)	U.S.A. (mid S)
	Rhopalosiphum padi	Wheat (Triticum)	U.S.A. (mid S)
	Schizaphis graminum	Wheat (Triticum)	U.S.A. (mid S)
Lysiphlebus testaceipes (parasitoid)	Schizaphis graminum	Wheat (Triticum)	U.S.A. (mid S)