PREDICTIONS OF ADULT ANOPHELES-ALBIMANUS DENSITIES IN VILLAGES BASED ON DISTANCES TO REMOTELY-SENSED LARVAL HABITATS

Remote sensing is particularly helpful for assessing the location and extent of vegetation formations, such as herbaceous wetlands, that are difficult to examine on the ground. Marshes that are sparsely populat ed with emergent macrophytes and dense cyanobacterial mats have previo usly been identified as very productive Anopheles albimanus larval hab itats. This type of habitat was detectable on a classified multispectr al Systeme Probatoire d'Observation de la Terre image of northern Beli ze as a mixture of two isoclasses. A similar spectral signature is cha racteristic for vegetation of river margins consisting of aquatic gras ses and water hyacinth, which constitutes another productive larval ha bitat. Based on the distance between human settlements (sites) of vari ous sizes and the nearest marsh/river exhibiting this particular class combination, we selected two groups of sites: those located closer th an 500 m and those located more than 1,500 m from such habitats. Based on previous adult collections near larval habitats, we defined a land ing rate of 0.5 mosquitoes/human/min from 6:30 PM to 8:00 PM as the th reshold for high (greater than or equal to 0.5 mosquitoes/human/min) v ersus low (< 0.5 mosquitoes/human/min) densities of An. albimanus. Sit es located less than 500 m from the habitat were predicted as having v alues higher than this threshold, while lower values were predicted fo r sites located greater than 1,500 m from the habitat. Predictions wer e verified by collections of mosquitoes landing on humans. The predict ions were 100% accurate for sites in the > 1,500-m category and 89% ac curate for sites in the < 500-m category.