Native Argentinean cyclopoids (Crustacea: Copepoda) as predators of Aedes aegypti and Culex pipiens (Diptera: Culicidae) mosquitoes

Copepods from La Plata, Argentina were investigated to characterize the local community of larvivorous copepods inhabiting mosquito breeding sites and to identify new predator species of the mosquitoes which occur in artificial containers, Aedes aegypti and Culex pipiens. Diversity of larvivorous cyclopoids was highest in permanent pools. Predation by sex and age, selectivity on mosquito species, and daily predation rate during five days were studied for Acanthocyclops robustus, Diacyclops uruguayensis, Macrocyclops albidus and Mesocyclops longisetus. Female copepods presented the highest predatory capacity. No predatory preference for mosquito species was found. According to overall predation potential, copepods were ranked as follows: D. uruguayensis < A. robustus < M. albidus < M. longisetus. Copepod tolerance to desiccation and capacity to survive in water from artificial containers were also evaluated. D. uruguayensis and A. robustus survived under dry conditions, but D. uruguayensis showed lower survival in water from cemetery flower vases. M. albidus did not survive under dry conditions and did not tolerate water extracted from artificial containers. M. longisetus survival was not severely reduced after desiccation or breeding in water from flower vases. The Neotropical cyclopoids D. uruguayensis and A. robustus can be considered good candidates and merit further research as biological control agents for mosquitoes. Rev. Biol. Trop. 57 (4): 1059-1068. Epub 2009 December 01.

Se hizo una prospección de copépodos en La Plata, Argentina, con los objetivos de caracterizar la comunidad local de copépodos larvívoros en sitios de cría de mosquitos, e identificar nuevas especies depredadoras de los mosquitos de contenedores artificiales Aedes aegypti y Culex pipiens. La diversidad de ciclopoides larvívoros fue máxima en charcos permanentes. Se examinó la depredación por sexos y edad, la selectividad por especies de mosquito, y la tasa de depredación diaria durante cinco días en Acanthocyclops robustus, Diacyclops uruguayensis, Macrocyclops albidus y Mesocyclops longisetus. Los copépodos hembra presentaron la capacidad depredadora más alta. No se encontró preferencia por alguna especie de mosquito. De acuerdo al potencial de depredación en general, los copépodos se ordenan así: D. uruguayensis < A. robustus < M. albidus < M. longisetus. También se evaluó la tolerancia a la desecación del hábitat y la capacidad de resistir en agua de contenedores artificiales. D. uruguayensis y A. robustus sobrevivieron en condiciones de sequía, pero D. uruguayensis presentó menor supervivencia en agua de floreros de cementerio. M. albidus no sobrevivió condiciones de sequía y no toleró el agua extraída de contenedores artificiales. Los ciclopoides neotropicales D. uruguayensis and A. robustus son buenos candidatos y merecen investigación ulterior como agentes de control biológico de mosquitos.

Efecto de la calidad del agua de criaderos de mosquitos (Diptera: Culicidae) sobre la patogenicidad e infectividad de las zoosporas del hongo Leptolegnia chapmanii (Straminipila: Peronosporomycetes)

Effect of water quality in mosquito breeding sites on the pathogenicity and infectivity of zoospores from the fungus Leptolegnia chapmanii (Straminipila: Peronosporomycetes). The fungus Leptolegnia chapmanii is highly pathogenic to mosquito larvae in Argentina. We studied if physical and chemical characteristics of the water from mosquito breeding sites affect pathogenicity, and the infectivity of zoospores of L. chapmanii. Water samples were taken from pools filled by rains, urban ditches with domestic waste water, pools filled by overflow from Río de la Plata, and flower vases from the Cemetery of La Plata city. Sub-samples of water were analyzed for physical and chemical characteristics, while other sub-samples were used for laboratory bioassays. Containers with 150 ml of water samples, 25 Aedes aegypti larvae, and 2.8 x 105 zoospores of L. chapmanii, were incubated under controlled environment, and larval mortality was recorded after 48 h. There were highly significant differences among mortalities in water from cemetery vases (70.2%), rain pools water (99.5%), and pools with water from Rio de la Plata (95%). There were no significant differences among larval mortalities in water from ditches, rain pools and Río de la Plata pools. Leptolegnia chapmanii was successful as a biological control agent in all kinds of tested water qualities, producing high larval mortality. Rev. Biol. Trop. 57 (1-2): 371-380. Epub 2009 June 30.

Leptolegnia chapmanii es un potente patógeno de larvas de mosquitos. El objetivo del trabajo fue determinar si las características físico-químicas del agua de criaderos de culícidos de importancia sanitaria a nivel mundial afectan la patogenicidad e infectividad de las zoosporas de L. chapmanii. Se tomaron muestras de cuatro tipos de agua en Argentina: de lluvia, de zanja, del Río de La Plata, y de floreros del cementerio local. A una parte del agua se le realizaron estudios físicos-químicos, y otra parte fue utilizada en ensayos. Se colocó 150 ml de cada muestra en recipientes plásticos, con 25 larvas sanas de Aedes aegypti y 2.8 x 105 zoosporas de L. chapmanii. Fueron incubadas a 25 ºC y 12-12 (L-O). La mortalidad larval fue registrada a las 48 horas. Se utilizaron tres recipientes y un control por tratamiento, con tres repeticiones realizadas en distintos días. Se observaron diferencias altamente significativas entre la mortalidad larval en aguas de floreros del cementerio (70.2%), aguas de lluvias (99.53%), y del río de La Plata (95%). No hubo diferencias significativas entre la mortalidad larval en agua de zanja, lluvia y río. Leptolegnia chapmanii resultó exitoso en los cuatro tipos de aguas evaluados, produciendo elevados niveles de mortalidad larval.

Variación estacional de tres especies de Culex (Diptera: Culicidae) y sus parásitos y patógenos en Punta Lara, provincia de Buenos Aires, Argentina / Seasonal variation of three Culex species (Diptera: Culicidae) and its parasites and pathogens in Punta Lara, Buenos Aires, Argentina

The seasonality of immatures, imagoes and pathogens of Culex dolosus Lynch Arrib lzaga, Culex intrincatus Brethes and Culex maxi Dyar from Punta Lara (Buenos Aires province, Argentina) was monitored weekly (larvae and pupae) or fortnightly (adults), from 1989 to 1991. Culex dolosus was present during all months. The larvae were parasitized by Geotrichum candidum Link ex Person, Smittium morbosum var. rioplatensis Lopez Lastra, Coelomomyces sp., Achlya sp, Amblyospora dolosi Garc­a & Becnel and Strelkovimermis spiculatus Poinar & Camino. Conidia of Hyphomycetes, filarial worms of Onchocercidae and S. spiculatus were detected in adults. Cx. intrincatus was present from January to May; the immatures were parasitized by G. candidum, S. morbosum, Achlya sp. and Amblyospora sp. Larvae of Cx. maxi were collected from January to April, and adults in all months except for June and July. S. morbosum was the only parasite found in this mosquito