ENVIRONMENTAL AND REGIONAL DETERMINANTS OF ANOPHELES (DIPTERA, CULICIDAE) LARVAL DISTRIBUTION IN BELIZE, CENTRAL-AMERICA

Surveys of Anopheles larval habitats in northern Belize were carried o ut during September 1990 and April 1991. At each site, larvae were col lected and the physical and chemical characteristics of water and spec ies composition of aquatic vegetation were measured or estimated. Data on presence or absence of four species, Anopheles albimanus Wiedemann , A. crucians Wiedemann, A. pseudopunctipennis Theobald, and A. argyri tarsis Robineau-Desvoidy, were used for analysis of associations with environmental factors, habitat types, and regions. Using significantly contributing environmental variables, discriminant functions (DF) wer e constructed for the Anopheles species, except for A. argyritarsis wh ose distribution could be predicted solely by altitude. The stability of DFs was checked by cross-validation runs. The DF for A. pseudopunct ipennis was 93% accurate in predicting positive habitats. Predictions based on DFs for A. albimanus and A. crucians were 74 and 80% accurate , respectively. Of the four Anopheles species present in the study are a, A. albimanus was the most common. Together with A. crucians, it occ urred mostly on the coastal plain, and both species were present in bo th wet and dry seasons. Anopheles albimanus was positively associated with cyanobacterial mats and submersed-periphyton habitat types and ne gatively associated with the filamentous algae habitat type. A. crucia ns was positively associated with Eleocharis-periphyton habitat type. A. pseudopunctipennis and A. argyritarsis were common only during the dry season and their distribution was limited to the Karst and Mountai n Pine Ridge regions. Both species were positively associated with the filamentous algae habitat type, and A. argyritarsis was also positive ly associated with the rock pools habitat type. Physical factors (e.g. , water depth, water temperature, and oxygen content) were usually mar ginally correlated with larval occurrence Dominant plant growth forms, such as filamentous algae, cyanobacterial mats, and submersed macroph ytes showed the closest association with the larvae of particular Anop heles species. Our results demonstrated the controlling influence of d ominant aquatic vegetation on larval presence.