Submitted to: Journal of Medical Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/17/2002
Publication Date: 11/6/2002
Citation: CRUZ-VAZQUEZ, C., ALTIMIRA, G., RAMOS, M., MEDINA, L., GARCIA-VAZQUEZ, Z., GEORGE, J.E. SUSCEPTIBILITY OF HAEMATOBIA IRRITANS (DIPTERA: MUSCIDAE) TO PERMETHRIN IN DAIRIES IN AGUASCALIENTES, MEXICO. JOURNAL OF MEDICAL ENTOMOLOGY. v. 39. p. 939-941. Interpretive Summary: Because of the abundance of horn flies on dairy cows confined in dairies in the State of Aguacalientes, Mexico, bioassays were done to determine if the cows were resistant to the permethrin insecticide used in an effort to control the flies. The bioassays proved that the horn flies on the cows were susceptible to permethrin. Because horn flies only develop in undisturbed manure, it was concluded that the continuing problem with the parasites was due to the migration of freshly emerged horn flies from the development of eggs deposited in manure from cattle grazing in pastures adjacent to the dairies. In the confinement pens the high density of cows would constantly disturb fresh manure before horn flies could complete their larval developmental cycle in the manure.
Technical Abstract: The purpose of this study was to conduct a survey for the susceptibility of the horn fly, Haematobia irritans (L.), populations to permetrin on dairy cattle from Aguascalientes, Mexico. Samples of populations of horn flies at 25 dairies were exposed to two discriminating doses (2.5 and 6.0 ug/cm-2) on permethrin-treated filter papers and the percentage of mortality was compared with that of a susceptible strain treated with same doses of permethrin. The results show that there was a difference in the mortality from two discriminating doses and the mortality of the susceptible strain. Therefore, horn fly populations at all dairies tested in Aguascalientes, Mexico, were susceptible to permethrin. This insecticide, as well as other pyrethroids, could continue to be used to provide satisfactory control of horn flies in the study region.