LANDSAT-TM IDENTIFICATION OF AMBLYOMMA-VARIEGATUM (ACARI, IXODIDAE) HABITATS IN GUADELOUPE

The objective of this study in 1986-1987 was to determine whether it was possible to remotely identify the specific habitat or habitats of the African bont tick, Amblyomma variegatum, using Landsat-TM imagery data. An unsupervised classification of the April 1986 image was carried out using LAS KMEANS and SPCSRT. The predictability of the landcover classes was determined by visiting random preselected sites within wetlands, woodlands, canefields, and grazing. On a second visit adult ticks were counted in over 103 herds and the habitats recorded. Descriminant analysis indicated that there were a limited number of tick habitats. The tick counts for the herds within these habitats indicate that each habitat probably has a characteristic tick density. The visible farms in Grande Terre, representing four habitats, were then compared with the landcover classes found in a 5 x 5 pixel array at each farm site in the classified image. The habitats could be separated using principal component analysis. Divisive clustering analysis was applied to the band values and derived indices for a similar sized array for each farm site visible in the original unclassified image of Guadeloupe. This analysis clustered the sites by large and small variance of band values, and by vegetation and moisture indices. Herds in heterogeneous sites with large variances had more ticks than those in homogeneous or low variance sites. Within the heterogeneous sites, those with high vegetation and moisture indices had more ticks than those with low values.