Evaluation of Culex pipiens larvae control by cyclopoid copepods in an urban cemetery of Montevideo, Uruguay.

Mosquitoes are vectors for several diseases including malaria, yellow and dengue fever, and encephalitis. Culex pipiens is a mosquito species with worldwide distribution whose larvae colonize temporary and permanent aquatic environments (Campos et al. 1993). Cx. pipiens is the most common species in Uruguay, where mosquito-mediated diseases are largely controlled, but the systematic reappearance of the dengue vector Aedes aegypti has caused particular concern (Willat et al. 2003) as dengue is still an endemic disease in neighboring Brazil and Argentina. Continued use of pesticides for mosquito control is a common practice but tends to generate chemical resistance in addition to seriously harming the environment (Schrieber and Jones 2000). Biological control is a promising alternative for keeping vector populations in check. 2005) indeed support that cyclopoid copepods (Crustacea) can be effective controllers for different mosquito species. Assessment of endemic copepod species is necessary in order to develop a biological control approach. In Uruguay, local strains of Mesocyclops longisetus, Macrocyclops albidus, and Acanthocyclops robustus were earlier found to significantly prey on 1 st instar Cx. pipiens under laboratory conditions (Calliari et al. 2003); in situ evaluation at preferential places of mosquito reproduction constitutes a necessary step for assessing their potential use as effective control agents. Here we report results of a field experiment to evaluate the capacity of M. longisetus and M. albidus to control natural populations of Cx. pipiens under realistic conditions in an urban cemetery of Montevideo, Uruguay. Experimental work was carried out between February and March 2006 (late summer) in La Teja cemetery in Montevideo, Uruguay. Montevideo has nearly 1.5 million inhabitants, and La Teja is the main cemetery in the SW urban area (34°51'S, 56°13'W). Three sites within the cemetery were selected (distance between sites ca. 100 m) with general characteristics assumed to favor larval mosquitoes (Fischer and Schweigmann 2004). Positive characteristics considered included the presence of ground vegetation (grasses or small bushes) and partial shadow cover from nearby trees. Such conditions were found throughout the cemetery: Sites #1 and #2 were covered by young and sparser perennial vegetation, while site #3 was under denser annual vegetation that kept it shaded all day during the study season. We monitored mosquito larvae in artificial containers with either M. longisetus, M. albidus, or without copepods (control containers). Copepods were obtained from several laboratory cultures, each started from a single egg-carrying female collected from the wild during previous months. Containers consisted …