Validation of a subjective counting method for a horn flies (Haematobia irritans irritans) (Diptera: Muscidae) population in a cattle herd.
A trained observer direct count method to measure horn fly population was evaluated to determine the reliability (inter-observer agreement) and its validity when compared with a "gold standard" method (video film). All the counts were performed with the animals restrained in a chute in a single herd. A direct count of horn flies by each of two observers on opposite sides of the animal was made. In addition a videotape recording of the counting surface on each animal was made. Horn flies were counted on 80 cows in the morning twice monthly from 22 October 1999 to 24 March 2000. The correlation between observer counts was high as was the correlation between observer counts and counts made from a videotape recording. Direct counts by trained observers were highly reliable and had good validity. However, videotape recording can be useful when the horn fly population is high, because it is faster in the field than the direct count method. The results of this study suggest that the direct count method can be used with confidence under field conditions.
Castro
Eleonor
E
Department of Parasitology, Faculty of Veterinary, Lasplaces 1550, C.P. 11600, Montevideo, Uruguay. elinor@adinet.com.uy
Gil
Andrés
A
Solari
María Angélica
MA
Farias
Nara Amélia
NA
D000818:Animals; D002417:Cattle; D002418:Cattle Diseases / Q000469:parasitology*; D004478:Ectoparasitic Infestations / Q000469:parasitology / Q000662:veterinary*; D005260:Female; D009117:Muscidae / Q000254:growth & development*; D015588:Observer Variation; D012044:Regression Analysis; D014583:Uruguay; D014743:Videotape Recording