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ARS Home » Plains Area » Fargo, North Dakota » Edward T. Schafer Agricultural Research Center » Insect Genetics and Biochemistry Research » Research » Publications at this Location » Publication #132615
Title: A DNA TEST FOR PARASITIZATION OF WHITEFLIES BY NATIVE AND EXOTIC ERETMOCERUS SPECIES

Author
item HEILMANN, LARRY - NORTH DAKOTA STATE UNIV
item ZHANG, JIANZHONG - NORTH DAKOTA STATE UNIV
item OLESON, ARLAND - NORTH DAKOTA STATE UNIV
item ANDRESS, EARL - USDA-APHIS BRAWLEY, CA
item GOULD, JULI - USDA-APHIS, PHOENIX AZ
item Nelson, Dennis

Submitted to: Molecular Insect Science International Symposium Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 3/27/2002
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: The whitefly, BemIsia agentifolii, is a serious pest of fruit and vegetable, cotton and alfalfa crops in the south and southwest. One method to control this pest has been biological control, the use of natural enemies. The Aphelinidae wasps of the genus Eretmocerus parasitize whitefly nymphs and have been a favorite control method in fields and greenhouses. To fight the recent introduction of the prolific silverleaf whitefly the USDA has conducted a worldwide search for Eretmocerus species useful against this species of whitefly. With introduction of foreign exotic species into the environment it becomes necessary to be able to follow the introduced species to determine its spread, its reproduction and its effect on native species. This is difficult with Eretmocerus because of its small size and the similar appearance of most species. No identification at all can be made on the embryonic wasps before they emerge as adults. We have developed a simple squash blot hybridization test using highly abundant but species-specific DNA probes that allows field tests of the rate of parasitization of whitefly nymphs and identifies the species of Eretmocerus parasites even at very early stages of development. We have used this in a large scale test in the Imperial Valley of California. More than 26,000 whitefly nymphs and pupae were collected from 307 sites on four different crops over eighteen months. They were squashed on filters and hybridized with the labeled species-specific probes. Approximately 21% were parasitized with the native E. eremicus species and 6% were parasitized by a variety of imported European-African-Asian species. We were able to show that about 80% of the parasitization by exotic species was due to one species from Ethiopia. Much lesser amounts were due to species from the United Arab Emirates and Pakistan. About 15% was due to other unidentified exotic species. This method could provide a simple way to follow and evaluate large scale field tests with these small insects.