MODELING/GIS, RISK ASSESSMENT,ECONOMIC IMPACT Distribution of Anopheles albimanus, Anopheles vestitipennis, and Anopheles crucians Associated with Land Use in Northern Belize JOHN P. GRIECO, 1 SARAH JOHNSON, 2 NICOLE L. ACHEE, 1 PENNY MASUOKA, 1 KEVIN POPE, 3 ELIS ˘ KA REJMA ´ NKOVA ´ , 2 ERROL VANZIE, 4 RICHARD ANDRE, 1 AND DONALD ROBERTS 1 J. Med. Entomol. 43(3): 614Ð622 (2006) ABSTRACT Anthropogenic land use changes often alter natural patterns of disease transmission. The goal of this study was to determine whether phosphorus input from sugarcane, Saccharum officinarum L., cultivation in northern Belize could pose a signiÞcant environmental impact on malaria transmission by changing vegetation structure and composition of wetlands and associated larval habitats. Our primary focus was on the increased dominance of cattail, Typha domingensis Pers., a favored habitat for Anopheles vestitipennis Dyar & Knab. A land cover classiÞcation based on satellite imagery was used to select 20 marshes impacted by agricultural runoff and 20 marshes surrounded by forest (nonimpacted). A 100-m transect was established into each of the 40 marshes. Water, vegetation, and larval sampling were conducted at the 0-, 10-, 25-, 50-, and 100-m locations along the transect. Analyses of larval density data indicated that Anopheles albimanus Wiedemann was negatively cor- related with percentage of cover of Typha (R 2 = 0.39, P  0.001) but positively correlated with sparse Eleocharis cellulosa Torr. (rush) cover (R 2 = 0.19, P  0.05) and presence of cyanobacterial mats (CBM) (R 2 = 0.33, P  0.0001). An. vestitipennis was found to be positively correlated with per- centage of cover of Typha (R 2 = 0.19, P  0.001). Canonical correspondence analysis identiÞed CBM and light as the variables associated with the presence of An. albimanus larvae, Typha cover with An. vestitipennis larvae, and Eleocharis and absence of light with Anopheles crucians (Wiedemann). A positive correlation also existed between marshes adjacent to agricultural activities and presence of An. vestitipennis (R 2 = 0.37, P  0.05). These results indicate that marshes in proximity to agricultural Þelds are conducive for Typha growth, thereby providing habitat for the more efÞcient malaria vector An. vestitipennis. KEY WORDS transect, land use, malaria, Belize, Anopheles The interaction of environmental variables associated with agricultural practices and their effect on malaria vector habitats is complex. Land use practices can alter plant productivity, soil and plant nutrient content, and nutrient cycling, which can then alter the structure and function of the ecosystem (Gathumbi et al. 2005). Nutrient runoff from fertilized agricultural lands has been documented to have an impact on wetland sys- tems (Richardson et al. 1999). Dramatic changes in vegetation types resulting from the introduction of fertilizers can further alter the richness and diversity of vertebrate and invertebrate species (Steinman et al. 2003). Plant community replacement leads to changes in habitat availability that can result in the displace- ment of one vector species while creating favorable conditions for another. Rejma ´ nkova ´ et al. (1988) doc- umented a transition from Culex tarsalis Coquillett in California rice (Oryza sp.) Þelds when plant heights were low, to Anopheles freeborni Aitken in the second half of the growing season when plant heights were high. Anopheles albimanus Wiedemann-dominated habitats, characterized by high sun exposure, transi- tioned to Anopheles punctimacula Dyar & Knab-dom- inated habitats when plant levels reached a height that shaded the waterÕs surface (Service 1989). Malaria transmission in northern Belize can be at- tributed to two primary vector species: Anopheles vestitipennis Dyar & Knab and An. albimanus. Re- cent studies focusing on the vector competence of these two species found differences in transmission potential (Grieco et al. 2005). Grieco et al. (2002) demonstrated that An. vestitipennis exhibits both strong endophagic and anthropophagic feeding be- haviors, whereas similar studies with An. albimanus show this species to be both weakly endophagic and anthropophilic. Achee et al. (2000) reported An. ves- titipennis with high minimum Þeld infection rates in vector surveys conducted throughout Belize, whereas these same rates were low for An. albimanus, suggest- The opinions and assertions contained in this article are not to be considered as ofÞcial or as reßecting the views of the Department of Defense or the Uniformed Services University of the Health Sciences. 1 Department of Preventive Medicine and Biometrics, Uniformed Services University of the Health Sciences, Bethesda, MD 20814. 2 Department of Ecology, University of CaliforniaÐDavis, Davis, CA 95616. 3 GEO Eco Arc Research, 16305 St. MaryÕs Church Road, Aquasco, MD 20608. 4 Ministry of Health, Belize, Central America. 0022-2585/06/0614Ð0622$04.00/0  2006 Entomological Society of America Downloaded from https://academic.oup.com/jme/article/43/3/614/880569 by guest on 13 January 2023