A summary of the problems related to the systematics of primary and secondary Brazilian anophelines vectors of malaria is presented.

BackgroundThe molecular phylogenetic relationships and population structure of the species of the Anopheles triannulatus complex: Anopheles triannulatus s.s., Anopheles halophylus and the putative species Anopheles triannulatus C were investigated.MethodsThe mitochondrial COI gene, the nuclear white gene and rDNA ITS2 of samples that include the known geographic distribution of these taxa were analyzed. Phylogenetic analyses were performed using Bayesian inference, Maximum parsimony and Maximum likelihood approaches.ResultsEach data set analyzed septely yielded a different topology but none provided evidence for the seption of An. halophylus and An. triannulatus C, consistent with the hypothesis that the two are undergoing incipient speciation. The phylogenetic analyses of the white gene found three main clades, whereas the statistical parsimony network detected only a single metapopulation of Anopheles triannulatus s.l. Seven COI lineages were detected by phylogenetic and network analysis. In contrast, the network, but not the phylogenetic analyses, strongly supported three ITS2 groups. Combined data analyses provided the best resolution of the trees, with two major clades, Amazonian (clade I) and trans-Andean + Amazon Delta (clade II). Clade I consists of multiple subclades: An. halophylus + An. triannulatus C; trans-Andean Venezuela; central Amazonia + central Bolivia; Atlantic coastal lowland; and Amazon delta. Clade II includes three subclades: Panama; cis-Andean Colombia; and cis-Venezuela. The Amazon delta specimens are in both clades, likely indicating local sympatry. Spatial and molecular variance analyses detected nine groups, corroborating some of subclades obtained in the combined data analysis.ConclusionCombination of the three molecular markers provided the best resolution for differentiation within An. triannulatus s.s. and An. halophylus and C. The latest two species seem to be very closely related and the analyses performed were not conclusive regarding species differentiation. Further studies including new molecular markers would be desirable to solve this species status question. Besides, results of the study indicate a trans-Andean origin for An. triannulatus s.l. The potential implications for malaria epidemiology remain to be investigated.

BackgroundAnopheles (Kerteszia) cruzii is the primary vector of human and simian malarias in Brazilian regions covered by the Atlantic Rainforest. Previous studies found that An. cruzii presents high levels of behavioural, chromosomal and molecular polymorphisms, which led to the hypothesis that it may be a complex of cryptic species. Here, An. cruzii specimens were collected in five sites in South-East Brazil located at different altitudes on the inner and coastal slopes of two mountain ranges covered by Atlantic Rainforest, known as Serra do Mar and Serra da Mantiqueria. Partial sequences for two genes (Clock and cpr) were generated and compared with previously published sequences from Florianópolis (southern Brazil). Genetic diversity was analysed with estimates of population structure (FST) and haplotype phylogenetic trees in order to understand how many species of the complex may occur in this biome and how populations across the species distribution are related.ResultsThe sequences from specimens collected at sites located on the lower coastal slopes of Serra do Mar (Guapimirim, Tinguá and Sana) clustered together in the phylogenetic analysis, while the major haplotypes from sites located on higher altitude and at the continental side of the same mountains (Bocaina) clustered with those from Serra da Mantiqueira (Itatiaia), an inner mountain range. These two An. cruzii lineages showed statistically significant genetic differentiation and fixed characters, and have high FST values typical of between species comparisons. Finally, in Bocaina, where the two lineages occur in sympatry, we found deviations from Hardy-Weinberg equilibrium due to a deficit of heterozygotes, indicating partial reproductive isolation. These results strongly suggest that at least two distinct lineages of An. cruzii (provisorily named “Group 1” and “Group 2”) occur in the mountains of South-East Brazil.ConclusionsAt least two genetically distinct An. cruzii lineages occur in the Atlantic Forest covered mountains of South-East Brazil. The co-occurrence of distinct lineages of An. cruzii (possibly incipient species) in those mountains is an interesting biological phenomenon and may have important implications for malaria prevalence, Plasmodium transmission dynamics and control.Electronic supplementary materialThe online version of this article (10.1186/s13071-018-2615-0) contains supplementary material, which is available to authorized users.

Anopheles halophylus Silva-do-Nascimento & Lourenço-de-Oliveira was recently described using morphological and biological variants in specimens previously identified as Anopheles triannulatus (Neiva & Pinto). Because these two species occur in sympatry in central Brazil, we used allozymes to determine the extent of gene flow to confirm that they are different species. Of 11 allozyme loci analyzed, one (Mpi) was found to be diagnostic for An. halophylus and An. triannulatus, confirming their specific status. This locus revealed a second sibling species within An. triannulatus sensu lato. An. halophylus and the new undescribed species were confirmed using random amplified polymorphic DNA markers that showed moderate genetic divergence among these three sympatric and closely related taxa (D = 0.145-0.428). Moreover, this marker indicates that An. halophylus and the new species are more closely related to each other than either is to An. triannulatus.

BackgroundMany indigenous villages in the Amazon basin still suffer from a high malaria burden. Despite this health situation, there are few studies on the bionomics of anopheline larvae in such areas. This publication aims to identify the main larval habitats of the most abundant anopheline species and to assess their associations with some environmental factors.MethodsWe conducted a 19-month longitudinal study from January 2013 to July 2014, sampling anopheline larvae in two indigenous Yanomami communities, comprised of four villages each. All natural larval habitats were surveyed every two months with a 350 ml manual dipper, following a standardized larval sampling methodology. In a third study area, we conducted two field expeditions in 2013 followed by four systematic collections during the long dry season of 2014–2015.ResultsWe identified 177 larval habitats in the three study areas, from which 9122 larvae belonging to 13 species were collected. Although species abundance differed between villages, An. oswaldoi (s.l.) was overall the most abundant species. Anopheles darlingi, An. oswaldoi (s.l.), An. triannulatus (s.s.) and An. mattogrossensis were primarily found in larval habitats that were partially or mostly sun-exposed. In contrast, An. costai-like and An. guarao-like mosquitoes were found in more shaded aquatic habitats. Anopheles darlingi was significantly associated with proximity to human habitations and larval habitats associated with river flood pulses and clear water.ConclusionsThis study of anopheline larvae in the Brazilian Yanomami area detected high heterogeneities at micro-scale levels regarding species occurrence and densities. Sun exposure was a major modulator of anopheline occurrence, particularly for An. darlingi. Lakes associated with the rivers, and particularly oxbow lakes, were the main larval habitats for An. darlingi and other secondary malaria vectors. The results of this study will serve as a basis to plan larval source management activities in remote indigenous communities of the Amazon, particularly for those located within low-order river-floodplain systems.Electronic supplementary materialThe online version of this article (10.1186/s13071-017-2517-6) contains supplementary material, which is available to authorized users.

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Malaria transmission in South America is overwhelmingly located in the Amazon region with limited cases outside that biome. A key factor in the mitigation of malaria transmission is the determination of vector diversity and bionomics in endemic areas. Anopheles mosquitoes were collected in four different landscapes of Cruzeiro do Sul‐Acre, the current area with highest malaria transmission in Brazil. We performed adult mosquito collections every three months over two years and associated vector occurrence with local abiotic factors. A total of 1,754 Anopheles belonging to nine species were collected, but only four of them (An. albitarsis s.l. Lynch‐Arribalzaga, An. braziliensis Chagas, An. peryassui Dyar and Knab, and An. triannulatus Neiva and Pinto) represented 77.1% of the total. Vector density and diversity was uneven across field sites and collection periods. Higher Anopheles abundance (54.8%) and richness were observed in a deforested palm tree area (IFC), with An. braziliensis the most frequent mosquito (40.5%). Only 7.3% of mosquitoes were collected in the SAB village, but 66.4% of them were An. darlingi and An. oswaldoi, species often regarded as primary and secondary vectors of malaria in the Amazon region. A distinct biting preference was observed between 18:00‐19:40. The distance from the nearest breeding site and minimum temperature explained 41.6% of the Anopheles community composition. Our data show that the Anopheles species composition may present great variation on a microgeographic scale.