Description of microsporidia in simulids: molecular and morphological characterization of microsporidia in the larvae of Simulium pertinax Kollar (Diptera: Simuliidae)

Authors: DE CARVALHO, IMVG - Centro De Pesquisas Rene' Rachou; DE QUEIROZ, ATL - Centro De Pesquisas Rene' Rachou; DE MORAES, RB - Superintendência De Controle De Endemias (SUCEN); GIL, HB - Universidade Federal De Sao Carlos; ALVES, R - Universidade Federal De Sao Carlos; VIVIANI, ADB - Superintendência De Controle De Endemias (SUCEN); Becnel, James; DE ARAUJO-COUTINHO, CJPD - Superintendência De Controle De Endemias (SUCEN)

Submitted to: Brazilian Society Of Tropical Medicine (SBMT)
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/9/2014
Publication Date: 10/31/2014
Citation: De Carvalho, I., De Queiroz, A., De Moraes, R., Gil, H., Alves, R., Viviani, A., Becnel, J.J., De Araujo-Coutinho, C. 2014. Description of microsporidia in simulids: molecular and morphological characterization of microsporidia in the larvae of Simulium pertinax Kollar (Diptera: Simuliidae). Brazilian Society Of Tropical Medicine (SBMT). 47(5):624-631.

Interpretive Summary: Biting flies (mosquitoes, black flies etc.) are important transmitters of diseases to man and animals worldwide. Scientists with the Mosquito and Fly Research Unit located at the USDA/ARS Center for Medical, Agricultural and Veterinary Entomology in Gainesville, Florida, USA in collaboration with scientists at the Laboratório de Parasitologia, Instituto Butantan, São Paulo, Brazil and Laboratório de Entomologia Médica, Superintendência de Controle de Endemias, São Paulo, Brazil are developing new biologically based control strategies for biting flies. Development of new biological pesticides and/or control strategies for vector and pest flies becomes increasingly important as human populations grow and new and exotic disease agents appear. Such strategies can help prevent contamination of the environment with chemical pesticides that threaten man and contribute to a decline in biodiversity. This collaborative US and Brazilian study examines natural disease causing agents (microsporidia) from black flies in Brazil. Microsporidia are common pathogens of black flies but fundamental knowledge on their life cycles, modes of transmission and taxonomic placement are incomplete. In this investigation, we have conducted molecular and morphological studies on microsporidia from black flies. This fundamental information will enable scientists to evaluate the natural control of black flies by these pathogens and to develop complementary strategies to reduce disease transmission. This project has provided a better understanding of these control agents that have a high specificity for the vector species and can serve to reduce the use of broad-spectrum pesticides, which will result in fewer negative environmental consequences.

Technical Abstract: Microsporidia constitute the most common black fl y pathogens, although the species’ diversity, seasonal occurrence and transmission mechanisms remain poorly understood. Infections by this agent are often chronic and non-lethal, but they can cause reduced fecundity and decreased longevity. The objective of this study was to identify microsporidia infecting Simulium (Chirostilbia) pertinax (Kollar, 1832) larvae from Caraguatatuba, State of São Paulo, Brazil, by molecular and morphological characterization. Larvae were collected at a single point in a stream in a rural area of the city and were kept under artificial aeration until analysis. Polydispyrenia spp. infection was characterized by the presence of at least 32 mononuclear spores measuring 6.9 ± 1.0 x 5.0 ± 0.7µm in persistent sporophorous vesicles. Similarly, Amblyospora spp. were characterized by the presence of eight uninucleate spores measuring 4.5 x 3.5µm in sporophorous vesicles. The molecular analysis confi rmed the presence of microsporidian DNA in the 8 samples (prevalence of 0.51%). Six samples (Brazilian larvae) were related to Polydispyrenia simulii and Caudospora palustris reference sequences but in separate clusters. One sample was clustered with Amblyospora spp. Edhazardia aedis was the positive control taxon. Samples identifi ed as Polydispyrenia spp. And Amblyospora spp. were grouped with P. simulii and Amblyospora spp., respectively, corroborating previous results. However, the 16S gene tree showed a considerable distance between the black fly-infecting Amblyospora spp. and the mosquito-infecting spp. This distance suggests that these two groups are not congeneric. Additional genomic region evaluation is necessary to obtain a coherent phylogeny for this group.