Further study on Ascogregarina culicis in temperate Argentina: Prevalence and intensity in Aedes aegypti larvae and pupae Andrea Paola Albicócco a , Darío Vezzani a,b, * a Unidad de Ecología de Reservorios y Vectores de Parásitos, Departamento de Ecología, Genética y Evolución, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Pabellón 2, 4° piso, (C1428EHA) Buenos Aires, Argentina b Consejo Nacional de Investigaciones Científicas y Técnicas, Avda Rivadavia 1917 (C1033AAJ), Buenos Aires, Argentina article info Article history: Received 6 November 2008 Accepted 8 May 2009 Available online 18 May 2009 Keywords: Gregarines Ascogregarina culicis Mosquitoes Prevalence Intensity South America abstract The bionomics of South American strains of Ascogregarina spp. are poorly known and the first studies were performed a few years ago. Our main objective was to characterize Ascogregarina culicis population in Aedes aegypti immatures in temperate Argentina. A total of 1800 water-filled containers were inspected within a cemetery of Buenos Aires City through a reproductive period of the host (October 2006–June 2007). The parasite was detected in 16.7% (329/1974) of the immatures and 8.5% (15/177) of the breeding sites. The prevalence decreased from 19.9% in larvae to 6.5% in pupae. In those infected breeding sites, about 85% of the immature mosquitoes harbor the parasite with a median intensity of nine trophozoites per larva and six gametocysts per pupa. The prevalence in shaded containers was higher than in sun exposed ones but the intensity of the infection was quite similar between both lighting con- ditions. Sun-exposed containers recorded water temperatures significantly higher than those under shade throughout the study period. Parasite trophozoites were only found from January to May with a clear seasonal pattern of prevalence. Monthly values of parasite prevalence and mosquito host (percent- age of breeding sites and number of immatures) were significantly correlated at p < 0.05 when a temporal delay of two months was considered. Our results suggest that parasite prevalence is spatially and tem- porally heterogeneous in temperate urban Argentina, and these variations are associated with the host abundance. Ó 2009 Elsevier Inc. All rights reserved. 1. Introduction The aseptate gregarines of the genus Ascogregarina (Apicom- plexa: Lecudinidae) are host-specific parasites of dipterans, mainly mosquitoes (Chen, 1999). The parasite develops almost entirely within the host, being the oocyst the only free-living stage; see Chen (1999) and Tseng (2007) for detailed descriptions of the par- asite life cycle. Among the 11 Ascogregarina spp. that parasitize mosquitoes (Chen, 1999; Roychoudhury et al., 2007), Ascogregarina culicis attracted several researchers due to its potential role as bio- control agent of the dengue vector Aedes aegypti. However, until the present there is no consensus about the usefulness of Ascogreg- arina spp. for mosquito control; see Tseng (2007). Regardless of this, they could be considered suitable models for the study of par- asite-host relationships mainly due to host specificity, the large size of the trophozoites and the developmental synchronization with the host (Chen, 1999). Some aspects of the bionomics of A. culicis, such as seasonality and distribution, have been studied in field surveys in different re- gions (e.g. Barrett et al., 1971; Beier et al., 1995; Passos and Tadei, 2008). Laboratory studies suggested that high water temperatures reduce trophozoite survival (Mourya et al., 2004) and oocyst viabil- ity (McCray et al., 1970). In the same way, long periods of dryness could have a central role on oocyst viability (Roychoudhury and Kobayashi, 2006) and similar responses occur in Ascogregarina tai- wanensis and Ascogregarina barreti infecting Aedes albopictus and Ochlerotatus triseriatus, respectively (Chen and Yang, 1996; Van Rhein et al., 2000). These studies usually quantified parasite popu- lation by estimating prevalence and intensity in larvae, but infor- mation regarding infection in pupae or adults is lacking. Also, data about the proportion of infected breeding sites and infected immatures per container are surprisingly rare in field studies. In South America, only A. culicis and A. taiwanensis have been re- ported and the knowledge about the ecological features of these species is seriously scarce in the region. Researches on Ascogregari- na infections were undertaken in recent years in Brazil (Tadei and Passos, 2004; Passos and Tadei, 2008) and Argentina (Dellapé et al., 0022-2011/$ - see front matter Ó 2009 Elsevier Inc. All rights reserved. doi:10.1016/j.jip.2009.05.003 * Corresponding author. Address: Unidad de Ecología de Reservorios y Vectores de Parásitos, Departamento de Ecología, Genética y Evolución, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Pabellón 2, 4° piso, (C1428EHA) Buenos Aires, Argentina. Fax: +54 11 4576 3354. E-mail address: vezzani@ege.fcen.uba.ar (D. Vezzani). Journal of Invertebrate Pathology 101 (2009) 210–214 Contents lists available at ScienceDirect Journal of Invertebrate Pathology journal homepage: www.elsevier.com/locate/yjipa