Prevalence of Acanthamoeba spp. (Sarcomastigophora: Acanthamoebidae) in wild populations of Aedes aegypti (Diptera: Culicidae)

Studies of interrelationship between microorganisms and mosquitoes are of great importance, since it can provide support for better understand related to biology, development and their control. In this way, it is known that mosquito larvae and free-living amoebae (FLA) normally occupy similar aquatic microhabitats. However, few studies have been conducted about such coexistence. For that reason, the objective of the present study was to verify the prevalence of Acanthamoeba spp. in wild populations of Aedes aegypti, as well as to characterize the genotypic lineage, and their possible pathogenicity through thermo- and osmotolerance. Amoebae were investigated in 60 pools, each containing ten larvae of A. aegypti, collected in Porto Alegre (Rio Grande do Sul, Brazil). The Acanthamoeba isolates were morphologically characterized and submitted to the polymerase chain reaction technique to confirm identification of the genus. In addition, genotype analyses as well as tests for presumptive pathogenicity in some samples were performed. Of the 60 pools examined, 54 (90 %) were positive for FLA. Of these isolates, 47 (87 %) belonged to the genus Acanthamoeba. The genotypic groups T4, T3 and T5 were identified, numbering 14 (53.8 %), ten (38.5 %) and two (7.7 %) isolates, respectively. The physiological tests performed with 14 strains showed that 12 (85.7 %) were non-pathogenic, while two (14.3 %) were considered as having low pathogenic potential. These results provide a basis for a better understanding of the interaction between these protozoan and mosquitoes in their natural habitat. This study is the first to report the isolation of Acanthamoeba spp. from wild mosquitoes.