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United States Department of Agriculture

Agricultural Research Service

Title: Pcr Screening of Haematobia Irritans Irritans (Dipera: Muscidae) Populations for Pyrethroid Resistance-Associated Sodium Channel Gene Mutations

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

Submitted to: Journal of Medical Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: January 2, 1998
Publication Date: N/A

Interpretive Summary: Resistance monitoring in horn fly populations is done by filter paper bioassays which provide data on LC50 values but no information about the presence of specific resistance genes in the population. In addition, use of this assay does not readily evaluate changes of resistance levels in response to different insecticidal treatment or integrated pest management regimes. To improve the ability to monitor the resistance status of horn fly populations, a PCR-based rapid screening procedure was developed to test for the presence of a specific resistance-associated nucleotide substitution in the sodium channel gene which is the site of action of the pyrethroid class of insecticides. This PCR assay can identify pyrethroid susceptible or resistant sodium channel gene alleles from individual flies. Laboratory and wild populations were examined by both the PCR assay and conventional filter paper bioassays to verify that populations containing higher proportions of individuals with the resistant sodium channel allele sequence also had higher bioassay LC50 values. The PCR assay for resistance alleles gives definitive information on the genotype of an individual fly and can detect the presence of heterzygous individuals that might serve as reservoirs of resistance genes in wild populations.

Technical Abstract: A PCR-based rapid screening procedure was developed to test individual horn flies, Haematobia irritans irritans (L.) for the presence of a specific nucleotide substitution in the sodium channel gene sequence which has been associated with pyrethroid resistance. By a systematic optimization of reaction conditions and judicious choice of PCR primers differing in DNA sequence by a single nucleotide, this PCR assay can identify pyrethroid susceptible or resistant sodium channel alleles from individual flies. Laboratory and wild populations were examined by both the PCR assay and conventional filter paper bioassays to verify that populations containing higher proportions of individuals with the resistant sodium channel allele DNA sequence also had higher bioassay LD50 values. The PCR assay for resistance alleles gives definitive information on the genotype of an individual fly, requires less preparation time than the filter paper bioassay, does not require handling toxic insecticides and can detect the presence of heterozygous individuals that might serve as reservoirs of resistance genes in wild populations.

Last Modified: 8/27/2014
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