IMPROVEMENT OF FIELD SAMPLING METHODS FOR ADULT KAROO PARALYSIS TICKS, IXODES-RUBICUNDUS (ACARI, IXODIDAE), THROUGH ADDITION OF HOST ODOR

The responsiveness of Ixodes rubicundus ricks on questing substrates a nd the success of their attachment to non-living substrates were inves tigated. The purpose of this study was to relate responsiveness to con ditions of temperature and humidity, to compare the efficacy of flaggi ng and dragging methods to estimate the size of populations of adult I . rubicundus in the field, and to determine the possible influence of host odour on the efficacy of these methods. Responsiveness was tested under varying conditions of temperature and humidity under field cond itions, and the same ticks were used to determine the duration of atta chment to a flannel cloth, either impregnated with host odour from she ep wool or without it. Flagging and dragging methods were compared und er laboratory conditions with cloths either treated with host odour or not. Within the range of ambient temperatures recorded during this st udy (7-25 degrees C) most of the ticks (86%) were responsive. No obvio us relationship between temperature, relative humidity and responsiven ess of ticks was evident. Ticks remained on average 32.9 seconds (n=64 ) on cloth treated with host odour compared to 9.1 seconds (n=54) on u ntreated cloth. Flagging was 1.5-1.7 times as effective as dragging an d treatment of the cloths with host odour increased the efficacy 2.4 ( dragging) to 2.8 (flagging) times. The reactions of ticks to external stimuli should, therefore, be taken into account to maximize field sam pling success.