Comparisons of sampling methods for recording the numbers of Rocky Mountain wood ticks (Dermacentor andersoni) on cattle and range vegetation during control experiments
1985 - Volume: 26 Issue: 2 pages: 131-139
Methods of sampling
Methods of sampling populations of adult Dermacentor andersoni were tested and compared as part of a 13-year experiment which began in 1959. Tick counts were made in four fields, two of which were stocked with cattle during the tick season for the first five years. Cattle in field A were untreated; in field B, cattle were treated with acaricides or ticks were removed by hand-picking. Fixed quadrats were sampled in all fields. In the two stocked fields, randomly selected quadrats were also sampled. Two smaller fields were kept unstocked for 5 and 4 years respectively. The counts of ticks on cattle were highly correlated to counts of host-seeking ticks on fixed quad rats in field A in 1959-63. Counts of ticks on fixed and randomly selected quadrats showed similar trends in fields A and B in 1963-68. However, the counts on the fixed quadrats needed division by about 4 in field A and by 17 in field B, to give a tick/unit area index comparable to the more extensive random samples. Stratification increased the efficiency of random sampling. The area sampled per day increased with size of quadrat, within the limits tested. Calculations based on six sizes tested in 1967 indicated that minimum standard error would be obtained with 279- m2 quadrats. For future use, stratified random sampling would be the preferred method of sampling ticks on vegetation, but the simpler fixed quad rats may sometimes be useful as indicators of annual trends in numbers, or when they occupy a high proportion of the area to be sampled. Counts of ticks on both cattle and random C}uadrats need transformation before analysis of variance. Tick counts in the two unstocked fields declined only slowly during 1959-63, indicating that exclusion of stock, even for five years, may be ineffective in usefully reducing tick numbers.
Please read and follow the instructions
to post any comment or correction.