FACTORS AFFECTING THE DETECTION OF INFESTATIONS OF BOOPHILUS MICROPLUS IN TICK CONTROL PROGRAMS

Abstract

Factors affecting the probability of detecting infestations of Boophilus microplus when herds of cattle are examined were studied. The probability of detecting a tick depends on the number of infested cattle in the herd, the probability of ticks being present on the areas of the beast examined, the efficiency of the examination and the proportion of the herd examined. A mathematical expression relating these factors was derived, and a range of values calculated to demonstrate the relative importance of each factor. It was evident that the efficiency of the examination should be kept better than 75%, and that it is necessary to employ a high sampling rate, preferably 100% of the herd. The probabilities of ticks being present on 6 predilection sites and 4 combinations of sites of an infested animal were determined experimentally. The tail butt, esutcheon, belly, dewlap and to a lesser degree neck and ear were all very suitable sites on which to find cattle ticks. A combination of tail butt, escutcheon and neck produced probabilities (0.58 and above) considered adequate to form the basis of an examination system. Examination systems used in New South Wales, Queensland, Argentina and at the United States-Mexico border are described. As a result of this study a new standardised system has been adopted by the Board of Tick Control for use by all New South Wales inspectors.

Competição intraespecífica em Boophilus microplus

“…Foi observada uma migração preferencial do parasito para determinadas regiões do corpo dos bovinos, tais como: entrepernas, tábua do pescoço, barbela e base da cauda. Os locais mais requisitados para fixação dos carrapatos no hospedeiro foram os mesmos citados por autores como PALMER et al (1976( ) e GONZALES (1993. Segundo SONENSHINE (1991), o sucesso da alimentação depende da habilidade do parasito em superar o sistema de defesa do hospedeiro e, de acordo com PEREIRA (1982), a autolimpeza (defesa por lambedura, pelo ato de se coçar, ou pela fricção de encontro a paredes ou outras superfícies) é um dos componentes mais importantes da resistência do bovino.…”

Integrated Strategy for Sustainable Cattle Fever Tick Eradication in USA is Required to Mitigate the Impact of Global Change

“…Probabilities of detecting infested animals or premises is the product of many interacting abiotic and biotic factors influencing spatial and temporal distributions of CFT (Palmer et al, 1976; Teel et al, 1997, 2003). When the resident population is low or widely dispersed due to weather conditions, early stage of establishment, or other factors, the probability of detection is low.…”

Simulated Cattle Fever Tick Infestations in Rotational Grazing Systems

“…The season of introduction of infested cattle in both the intensive and extensive systems affected the dynamics of tick dispersal and survival among pastures as well as occurrence of tick-free periods on the cattle. The dynamics of the system affect opportunities for detection of the infestation and potential intervention strategies with intensive SDG systems using variable rotation strategies (Palmer et al 1976, Sutherst et al 1979. Spring introductions would be more problematic for managers of intensive SDG than fall introductions, given the low frequency and duration of tickfree periods associated with spring introductions.…”