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United States Department of Agriculture

Agricultural Research Service

Title: Toxicological and Molecular Biological Characterization of Pyrethroid Resistant Horn Flies, Haematobia Irritans

Authors
item Guerrero, Felix
item Jamroz, Robert
item Kammlah, Diane
item Kunz, Sidney

Submitted to: Journal of Insect Biochemistry and Molecular Biology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: August 4, 1997
Publication Date: N/A

Interpretive Summary: The horn fly is a major pest of cattle imparting significant annual economic losses to producers. The development and spread of pyrethroid- resistant horn flies has led to increased problems controlling this pest. The site of action of pyrethroids appears to be the voltage- sensitive sodium channels. The resistance to the rapid knockdown effect of pyrethroids was mapped to a sodium channel gene locus in the housefly. Gel analysis of mRNA from pyrethroid-susceptible and -resistant horn flies detected products whose concentrations increased in association with pyrethroid-resistance. PCR screening experiments with over 260 DNA obligomers examining their potential for detecting resistance-associated DNA markers yielded only one marker, HF-77, whose presence consistently typed an individual fly as pyrethroid-resistant. Although HF-77 was not detected in any susceptible flies tested, it was present in only 16% of the resistant individuals. A 0.9 kb fragment of the sodium channel gene from pyrethroid-susceptible and -resistant flies has been cloned and sequenced. The amino acid sequences deduced from the sodium channel DNA of pyrethroid-resistant and -susceptible horn flies were identical over this region except for three amino acid substitutes which appeared to be associated with resistance.

Technical Abstract: Genomic DNA and mRNA from pyrethroid-susceptible and -resistant horn flies was examined for differences associated with resistance. Poly(A) + RNA was purified from susceptible and resistant flies and translated in vitro. SDS-PAGE analysis detected translation products whose concentrations increased in association with pyrethroid-resistance. RAPD-PCR screening of fgenomic DNA with over 260 DNA oligomers examining their potential for detecting resistance-associated markers yielded only one DNA marker, HF-77, whose presence consistently typed an individual fly as pyrethroid- resistant. Although HF-77 was not detected in any susceptible flies tested, it was present in only 16% of the resistant individuals. HF-77 was cloned and sequenced but does not appear to contain an open reading frame with significant similarity to known proteins and did not hybridize to poly(A) + RNA during Northern blot analysis. RT-PCR using degenerate primers derived from sequences of Musca domestica and Drosophila melanogaster sodium channels resulted in the cloning and sequencing of a 0.9 kb fragment of the sodium channel from pyrethroid-susceptible and -resistant flies. The amino acid sequences deduced from the sodium channel DNA of pyrethroid-resistant and -susceptible horn flies were identical over this region except for three amino acid substitutions.

Last Modified: 8/22/2014
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