The effect of sample size and spatial scale on Taylor's power law parameters for the coffee berry borer (Coleoptera:Scolytidae)
Using estimated parameters log 10 a and b of Taylor's power law (TPL), different sampling schemes (random, systematic, and clusters), aggregation scales (branch, tree, area, and double area), and sampled sizes (2 to 700) were evaluated during 1994 and 1995 in an analysis of an extensive set of counts of the coffee berry borer (Hypothenemus hampei) from the central region of Colombia. Values of b greater than 1 (P minor who 0.01) were found in more than 90 percent of the regressions, the values ranging from 0.70 to 2.82 (an average of 1.67), indicating an aggregated pattern of this pest in the field. Values of log 10 a were from -2.11 to 1.95 (an average of 0.45). When the sample size was small, estimates were corrected for bias. No differences in estimates of either parameter were shown between the cluster and systematic schemes. The random sampling scheme showed marked differences for both log 10 a and b when compared with the clustering scheme, but there were differences in b but not log10a when compared with the systematic schemes. It was concluded that this was due to the random sampling scheme detecting greater degrees of aggregation, b values being estimated greater than 2.0. Differences in both log 10 a and b were shown for all changes in scale. Differences in sample size within the different sampling schemes were not reflected in log 10 a and b values. Possible causes of aggregation of the borer and practical applications of TPL parameters are described.
| Main Authors: | , , |
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| Format: | biblioteca |
| Published: |
2000
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| Subjects: | COFFEA, HYPOTHENEMUS HAMPEI, ORGANISMOS PATOGENOS, ENFERMEDADES DE LAS PLANTAS, METODOS ESTADISTICOS, COLOMBIA, |
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