Isoenzimatic analysis of four Anopheles (Kerteszia) cruzii (Diptera: Culicidae) populations of Brazil

Atlantic Forest Malaria: A Review of More than 20 Years of Epidemiological Investigation

In the south and southeast regions of Brazil, cases of malaria occur outside the endemic Amazon region near the Atlantic Forest in some coastal states, where Plasmodium vivax is the recognized parasite. Characteristics of cases and vectors, especially Anopheles (Kerteszia) cruzii, raise the hypothesis of a zoonosis with simians as reservoirs. The present review aims to report on investigations of the disease over a 23-year period. Two main sources have provided epidemiological data: the behavior of Anopheles vectors and the genetic and immunological aspects of Plasmodium spp. obtained from humans, Alouatta simians, and Anopheles spp. mosquitoes. Anopheles (K.) cruzii is the most captured species in the forest canopy and is the recognized vector. The similarity between P. vivax and Plasmodium simium and that between Plasmodium malariae and Plasmodium brasilianum shared between simian and human hosts and the involvement of the same vector in the transmission to both hosts suggest interspecies transfer of the parasites. Finally, recent evidence points to the presence of Plasmodium falciparum in a silent cycle, detected only by molecular methods in asymptomatic individuals and An. (K.) cruzii. In the context of malaria elimination, it is paramount to assemble data about transmission in such non-endemic low-incidence areas.

Kerteszia cruzii and extra-Amazonian malaria in Brazil: Challenges due to climate change in the Atlantic Forest

Kerteszia cruzii is a sylvatic mosquito and the primary vector of Plasmodium spp., which can cause malaria in humans in areas outside the Amazon River basin in Brazil. Anthropic changes in the natural environments are the major drivers of massive deforestation and local climate change, with serious impacts on the dynamics of mosquito communities and on the risk of acquiring malaria. Considering the lack of information on the dynamics of malaria transmission in areas across the Atlantic Forest biome, where Ke. cruzii is the dominant vector, and the impact of climate drivers of malaria, the present study aimed to: (i) investigate the occurrence and survival rate of Ke. cruzii based on the distinct vegetation profiles found in areas across the coastal region of the Brazilian Atlantic Forest biome; (ii) estimate the extrinsic incubation period (EIP) and survival rates of P. vivax and P. falciparum parasites in Ke. cruzii under current and future scenarios. The potential distribution of Plasmodium spp. was estimated using simulation analyses under distinct scenarios of average temperature increases from 1 °C to 3.7 °C. Our results showed that two conditions are necessary to explain the occurrence and survival of Ke. cruzii: warm temperature and presence of the Atlantic Forest biome. Moreover, both Plasmodium species showed a tendency to decrease their EIP and increase their estimated survival rates in a scenario of higher temperature. Our findings support that the high-risk malaria areas may include the southern region of the distribution range of the Atlantic Forest biome in the coming years. Despite its limitations and assumptions, the present study provides robust evidence of areas with potential to be impacted by malaria incidence in a future scenario. These areas should be monitored in the next decades regarding the occurrence of the mosquito vector and the potential for malaria persistence and increased occurrence.

Neotropical Anopheles (Kerteszia) mosquitoes associated with bromeliad-malaria transmission in a changing world

Kerteszia is a neotropical subgenus of Anopheles composed of 12 species. The species in this subgenus are strongly associated with humid forests rich in epiphytic bromeliads. Forest fragmentation and anthropogenic changes can therefore have a negative impact on the abundance and survival of these mosquito species. Within this subgenus, four species are considered primary vectors of malaria: An. cruzii, An. bellator, An. homunculus and An. neivai. Malaria cases associated with Kerteszia species are often referred to as bromeliad malaria, a type of malaria reported to be endemic in the coastal rainforest of the neotropical region since the end of the nineteenth century. Although the incidence of bromeliad-malaria cases has decreased since the middle of the last century, autochthonous malaria cases continue to be registered every year. The complexity of the epidemiology of bromeliad malaria appears to be increasing as asymptomatic plasmodial infections and transmission of simian Plasmodium to humans have recently been reported. Kerteszia vector species have a great affinity for human beings and can be found in human-modified areas close to forest fragments such as in the Extra-Amazonian region of Brazil, Colombian pacific coast, and the Caribbean coast. Deforestation and forest fragmentation have been occurring continuously in the biomes of the neotropical region, and findings of Kerteszia species in dwellings are frequent in this region. Controlling the species in the Kerteszia subgenus is particularly difficult because they move frequently from natural to rural and peri-urban areas in search of blood sources, posing a challenge for the development of control strategies based on integrated vector management. Furthermore, as it has been shown that some Kerteszia species share similar morphological and genetic characteristics, the existence of a species complex formed by cryptic, sibling species within the Kerteszia group in different areas in the South and Southeast of Brazil cannot be ruled out. The existence of such a complex could represent an obstacle to the control of Kerteszia species and consequently to the elimination of bromeliad-malaria transmission in these regions. Here, we review publications that focus on the biology and ecology of Kerteszia malaria vectors and their association with human-modified areas and bromeliad-malaria transmission.

Novel molecular evidence of population structure in Anopheles (Kerteszia) bellator from Brazilian Atlantic Forest

Anopheles bellator is a primary malaria vector in the Atlantic Forest. Partial sequences of timeless and Clock genes were used to assess the genetic differentiation of five Brazilian populations, which showed strong population structure (e.g. high F_ST values and fixed differences) in all pairwise comparisons between Bahia sample and the others from Paraná, São Paulo and Rio de Janeiro states. Also, the resulting phylogenetic trees clearly grouped the sequences from Bahia in a different cluster with high bootstrap values. Among southern and southeastern populations low levels of genetic differentiation were found suggesting a general stability of the genetic structure.

Cryptic diversity in an Atlantic Forest malaria vector from the mountains of South-East Brazil

BACKGROUND

Anopheles (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 (F _ST ) 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.

RESULTS

The 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 F _ST 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.

CONCLUSIONS

At 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.

An assay for the identification of Plasmodium simium infection for diagnosis of zoonotic malaria in the Brazilian Atlantic Forest

Zoonotic malaria poses a unique problem for malaria control. Autochthonous cases of human malaria in the Atlantic Forest have recently been attributed to Plasmodium simium, a parasite that commonly infects non-human primates in this Brazilian biome. However, due to its close similarity at both the morphological and molecular level to Plasmodium vivax, the diagnosis of P. simium in this region remains problematic. Therefore, a diagnostic assay able to accurately identify P. simium is important for malaria surveillance. Based on mitochondrial genome sequences, primers were designed to amplify a region containing a SNP specific to P. simium. This region can then be digested with the restriction enzyme HpyCH4III, which results in digestion of P. simium sequences, but not of any other malaria parasite. Fifty-two human and monkey blood samples from different regions and infected with different Plasmodium species were used to validate this protocol. This easy and inexpensive tool can be used for the diagnosis of P. simium in non-human primates and human infections from the Atlantic Forest region to monitor zoonotic malaria transmission in Brazil.

Morphogenetic characterisation, date of divergence, and evolutionary relationships of malaria vectors Anopheles cruzii and Anopheles homunculus

The mosquito species Anopheles cruzii and Anopheles homunculus are co-occurring vectors for etiological agents of malaria in southeastern Brazil, a region known to be a major epidemic spot for malaria outside Amazon region. We sought to better understand the biology of these species in order to contribute to future control efforts by (1) improving species identification, which is complicated by the fact that the females are very similar, (2) investigating genetic composition and morphological differences between the species, (3) inferring their phylogenetic histories in comparison with those of other Anophelinae, and (4) dating the evolutionary divergence of the two species. To characterise the species we used wing geometry and mitochondrial cytochrome oxidase subunit I (COI) gene as morphological and genetic markers, respectively. We also used the genes white, 28S, ITS2, Cytb, and COI in our phylogenetic and dating analyses. A comparative analysis of wing thin-plate splines revealed species-specific wing venation patterns, and the species An. cruzii showed greater morphological diversity (8.74) than An. homunculus (5.58). Concerning the COI gene, An. cruzii was more polymorphic and also showed higher haplotype diversity than An. homunculus, with many rare haplotypes that were displayed by only a few specimens. Phylogenetic analyses revealed that all tree topologies converged and showed [Anopheles bellator+An. homunculus] and [Anopheles laneanus+An. cruzii] as sister clades. Diversification within the subgenus Kerteszia occurred 2-14.2millionyears ago. The landmark data associated with wing shape were consistent with the molecular phylogeny, indicating that this character can distinguish higher level phylogenetic relationships within the Anopheles group. Despite their morphological similarities and co-occurrence, An. cruzii and An. homunculus show consistent differences. Phylogenetic analysis revealed that the species are not sister-groups but species that recently diverged within the Kerteszia group, perhaps concomitantly with the radiation of bromeliads in South America or during the Pleistocene climate oscillations.

Altitudinal population structure and microevolution of the malaria vector Anopheles cruzii (Diptera: Culicidae)

BACKGROUND

In Brazil, the autochthonous transmission of extra-Amazonian malaria occurs mainly in areas of the southeastern coastal Atlantic Forest, where Anopheles cruzii is the primary vector. In these locations, the population density of the mosquito varies with altitude (5-263 m above sea level), prompting us to hypothesise that gene flow is also unevenly distributed. Describing the micro-geographical and temporal biological variability of this species may be a key to understanding the dispersion of malaria in the region. We explored the homogeneity of the An. cruzii population across its altitudinal range of distribution using wing shape and mtDNA gene analysis. We also assessed the stability of wing geometry over time.

METHODS

Larvae were sampled from lowland (5-20 m) and hilltop (81-263 m) areas in a primary Atlantic Forest region, in the municipality of Cananéia (State of São Paulo, Brazil). The right wings of males and females were analysed by standard geometric morphometrics. Eighteen landmarks were digitised for each individual and a discriminant analysis was used to compare samples from the hilltop and lowland. A 400-bp DNA fragment of the mitochondrial cytochrome oxidase gene subunit I (CO-I) was PCR-amplified and sequenced.

RESULTS

Wing shapes were distinct between lowland and hilltop population samples. Results of cross-validated tests based on Mahalanobis distances showed that the individuals from both micro-environments were correctly reclassified in a range of 54-96%. The wings of hilltop individuals were larger. The CO-I gene was highly polymorphic (haplotypic diversity = 0.98) and altitudinally structured (Фst = 0.085 and Jaccard = 0.033). We found 60 different haplotypes but only two were shared by the lowland and hilltop populations. Wing shape changed over the brief study period (2009-2013).

CONCLUSIONS

Wing geometry and CO-I gene analysis indicated that An. cruzii is vertically structured. Wing shape varied rapidly, but altitude structure was maintained. Future investigations should identify the biotic/abiotic causes of these patterns and their implications in the local epidemiology of malaria.

Malaria in Brazil: what happens outside the Amazonian endemic region

Brazil, a country of continental proportions, presents three profiles of malaria transmission. The first and most important numerically, occurs inside the Amazon. The Amazon accounts for approximately 60% of the nation's territory and approximately 13% of the Brazilian population. This region hosts 99.5% of the nation's malaria cases, which are predominantly caused by Plasmodium vivax (i.e., 82% of cases in 2013). The second involves imported malaria, which corresponds to malaria cases acquired outside the region where the individuals live or the diagnosis was made. These cases are imported from endemic regions of Brazil (i.e., the Amazon) or from other countries in South and Central America, Africa and Asia. Imported malaria comprised 89% of the cases found outside the area of active transmission in Brazil in 2013. These cases highlight an important question with respect to both therapeutic and epidemiological issues because patients, especially those with falciparum malaria, arriving in a region where the health professionals may not have experience with the clinical manifestations of malaria and its diagnosis could suffer dramatic consequences associated with a potential delay in treatment. Additionally, because the Anopheles vectors exist in most of the country, even a single case of malaria, if not diagnosed and treated immediately, may result in introduced cases, causing outbreaks and even introducing or reintroducing the disease to a non-endemic, receptive region. Cases introduced outside the Amazon usually occur in areas in which malaria was formerly endemic and are transmitted by competent vectors belonging to the subgenus Nyssorhynchus (i.e., Anopheles darlingi, Anopheles aquasalis and species of the Albitarsis complex). The third type of transmission accounts for only 0.05% of all cases and is caused by autochthonous malaria in the Atlantic Forest, located primarily along the southeastern Atlantic Coast. They are caused by parasites that seem to be (or to be very close to) P. vivax and, in a less extent, by Plasmodium malariae and it is transmitted by the bromeliad mosquito Anopheles (Kerteszia) cruzii. This paper deals mainly with the two profiles of malaria found outside the Amazon: the imported and ensuing introduced cases and the autochthonous cases. We also provide an update regarding the situation in Brazil and the Brazilian endemic Amazon.

Morphology of the larvae, male genitalia and DNA sequences of Anopheles (Kerteszia) pholidotus (Diptera: Culicidae) from Colombia

Since 1984, Anopheles (Kerteszia) lepidotus has been considered a mosquito species that is involved in the transmission of malaria in Colombia, after having been incriminated as such with epidemiological evidence from a malaria outbreak in Cunday-Villarrica, Tolima. Subsequent morphological analyses of females captured in the same place and at the time of the outbreak showed that the species responsible for the transmission was not An. lepidotus, but rather Anopheles pholidotus. However, the associated morphological stages and DNA sequences of An. pholidotus from the foci of Cunday-Villarrica had not been analysed. Using samples that were caught recently from the outbreak region, the purpose of this study was to provide updated and additional information by analysing the morphology of female mosquitoes, the genitalia of male mosquitoes and fourth instar larvae of An. pholidotus, which was confirmed with DNA sequences of cytochrome oxidase I and rDNA internal transcribed spacer. A total of 1,596 adult females were collected in addition to 37 larval collections in bromeliads. Furthermore, 141 adult females, which were captured from the same area in the years 1981-1982, were analysed morphologically. Ninety-five DNA sequences were analysed for this study. Morphological and molecular analyses showed that the species present in this region corresponds to An. pholidotus. Given the absence of An. lepidotus, even in recent years, we consider that the species of mosquitoes that was previously incriminated as the malaria vector during the outbreak was indeed An. pholidotus, thus ending the controversy.

Evidence for the occurrence of two sympatric sibling species within the Anopheles (Kerteszia) cruzii complex in southeast Brazil and the detection of asymmetric introgression between them using a multilocus analysis

BACKGROUND

Anopheles (Kerteszia) cruzii (Diptera: Culicidae) is a primary vector of human and simian malaria parasites in southern and southeastern Brazil. Earlier studies using chromosome inversions, isoenzymes and a number of molecular markers have suggested that An. cruzii is a species complex.

RESULTS

In this study, a multilocus approach using six loci, three circadian clock genes and three encoding ribosomal proteins, was carried out to investigate in more detail the genetic differentiation between the An. cruzii populations from Florianópolis-Santa Catarina (southern Brazil) and Itatiaia-Rio de Janeiro States (southeastern Brazil). The analyses were performed first comparing Florianópolis and Itatiaia, and then comparing the two putative sympatric incipient species from Itatiaia (Itatiaia A and Itatiaia B). The analysis revealed high FST values between Florianópolis and Itatiaia (considering Itatiaia A and B together) and also between the sympatric Itatiaia A and Itatiaia B, irrespective of their function. Also, using the IM program, no strong indication of migration was found between Florianópolis and Itatiaia (considering Itatiaia A and B together) using all loci together, but between Itatiaia A and Itatiaia B, the results show evidence of migration only in the direction of Itatiaia B.

CONCLUSIONS

The results of the multilocus analysis indicate that Florianópolis and Itatiaia represent different species of the An. cruzii complex that diverged around 0.6 Mya, and also that the Itatiaia sample is composed of two sympatric incipient species A and B, which diverged around 0.2 Mya. Asymmetric introgression was found between the latter two species despite strong divergence in some loci.

Genetic variability among Anopheles species belonging to the Nyssorhynchus and Anopheles subgenera in the Amazon region

INTRODUCTION: Isoenzymatic analyses were performed involving species of the Nyssorhynchus and Anopheles subgenera in order to estimate the intra and interspecies genetic variability. METHODS: Mosquitoes were caught at different localities in the Amazon region. The collection and rearing of mosquitoes in the laboratory followed specific protocols. For the genetic variability analyses, the technique of horizontal electrophoresis on starch and starch-agarose gel with appropriate buffer systems was used. The alloenzyme variation was estimated using the Biosys-1 software. RESULTS: Out of the 13 loci, eight were polymorphic. Anopheles nuneztovari presented the largest number of alleles per locus, while the smallest number was detected in Anopheles marajoara from Macapá. The largest number of polymorphic loci was found for Anopheles marajoara from Maruanum and the smallest for Anopheles benarrochi (Guayará Mirim). Anopheles darlingi (Macapá) presented the greatest heterozygosity (Ho = 0.167 ± 0.071), while the lowest heterozygosity (Ho = 0.045 ± 0.019) was observed in Anopheles intermedius (Pacoval) of the subgenus Anopheles. Wright's F coefficient revealed considerable genetic structuring between the populations of Anopheles darlingi (Fst = 0.110) and between the populations of Anopheles marajoara (Fst = 0.082). CONCLUSIONS: Considering all the species studied, the genetic distance ranged from 0.008 to 1.114. The greatest distance was between Anopheles mattogrossensis and Anopheles oswaldoi, while the smallest was between the Anopheles benarrochi populations.

Estimation of divergence time between two sibling species of the Anopheles (Kerteszia) cruzii complex using a multilocus approach

Background

Anopheles cruzii is the primary human Plasmodium vector in southern and southeastern Brazil. The distribution of this mosquito follows the coast of the Brazilian Atlantic Forest. Previous studies indicated that An. cruzii is a complex of cryptic species.

Results

A multilocus approach using six loci, three circadian clock genes and three encoding ribosomal proteins, was implemented to investigate in more detail the genetic differentiation between the An. cruzii populations from Santa Catarina (southern Brazil) and Bahia States (northeastern Brazil) that represent two sibling species. The analysis revealed very high F_ST values and fixed differences between the two An. cruzii sibling species in all loci, irrespective of their function. An Isolation with Migration model was fit to the data using the IM program. The results reveal no migration in either direction and allowed a rough estimate of the divergence time between the two sibling species.

Conclusions

Population genetics analysis of An. cruzii samples from two Brazilian localities using a multilocus approach confirmed that they represent two different sibling species in this complex. The results suggest that the two species have not exchanged migrants since their separation and that they possibly diverged between 1.1 and 3.6 million years ago, a period of intense climatic changes.

Molecular evidence for the occurrence of a new sibling species within the Anopheles (Kerteszia) cruzii complex in south-east Brazil

Background

Anopheles cruzii (Diptera: Culicidae) has long been known as a vector of human and simian malaria parasites in southern and south-eastern Brazil. Previous studies have provided evidence that An. cruzii is a species complex, but the status of the different populations and the number of sibling species remains unclear. A recent analysis of the genetic differentiation of the timeless gene among An. cruzii populations from south and south-east Brazil has suggested that the population from Itatiaia, Rio de Janeiro State (south-east Brazil), is in a process of incipient speciation.

Methods

A ~180 bp fragment of cpr, a gene encoding the NADPH-cytochrome P450 reductase, an enzyme involved in metabolic insecticide resistance and odorant clearance in insects, was used in this study as a molecular marker to analyse the divergence between five An. cruzii populations from south and south-east Brazil.

Results

Analysis of the genetic differentiation in the cpr gene revealed very high F_ST values and fixed differences between Itatiaia and the other four populations studied (Florianópolis, Cananéia, Juquitiba and Santa Teresa). In addition, the data also provided preliminary evidence that seems to indicate the occurrence of two sympatric sibling species in Itatiaia.

Conclusions

Population genetics analysis of An. cruzii samples from different localities using a fragment of the cpr gene suggests that the Itatiaia sample represents at least one new sibling species in this complex.

Assessing the molecular divergence between Anopheles (Kerteszia) cruzii populations from Brazil using the timeless gene: further evidence of a species complex

BACKGROUND

Anopheles (Kerteszia) cruzii was the most important vector of human malaria in southern Brazil between 1930-1960. Nowadays it is still considered an important Plasmodium spp. vector in southern and south-eastern Brazil, incriminated for oligosymptomatic malaria. Previous studies based on the analysis of X chromosome banding patterns and inversion frequencies in An. cruzii populations from these areas have suggested the occurrence of three sibling species. In contrast, two genetically distinct groups among An. cruzii populations from south/south-east and north-east Brazil have been revealed by isoenzyme analysis. Therefore, An. cruzii remains unclear.

METHODS

In this study, a partial sequence of the timeless gene (approximately 400 bp), a locus involved in the control of circadian rhythms, was used as a molecular marker to assess the genetic differentiation between An. cruzii populations from six geographically distinct areas of Brazil.

RESULTS

The timeless gene revealed that An. cruzii from Itaparica Island, Bahia State (north-east Brazil), constitutes a highly differentiated group compared with the other five populations from south and south-east Brazil. In addition, significant genetic differences were also observed among some of the latter populations.

CONCLUSION

Analysis of the genetic differentiation in the timeless gene among An. cruzii populations from different areas of Brazil indicated that this malaria vector is a complex of at least two cryptic species. The data also suggest that further work might support the occurrence of other siblings within this complex in Brazil.

Diversidade de Culicidae durante os períodos crepusculares em bioma de Floresta Atlântica e paridade de Anopheles cruzii (Diptera: Culicidae)

O objetivo da investigação foi analisar a variação da diversidade e abundância das espécies de Culicidae e sua relação com algumas variáveis ambientais, bem como estimar a taxa de paridade de Anopheles cruzii Dyar & Knab, 1908. O estudo foi desenvolvido em Floresta Ombrófila Densa da Mata Atlântica, localizada no Estado do Paraná, denominada de Floresta Estadual do Palmito. As capturas foram executadas quinzenalmente, de dezembro 2006 a março 2007, com a técnica de "aspiração menor", nos crepúsculos vespertino e matutino, iniciando antes dos crepúsculos e finalizando após os crepúsculos. Foram detectadas 25 espécies, sendo as mais abundantes, Anopheles cruzii (65,2%), Culex sachettae Sirivanakarn & Jacob, 1982 (11,2%) e Anopheles bellator Dyar & Knab, 1906 (8,5%). De acordo com análise de variância, ocorreu diferença significativa na freqüência entre os períodos crepusculares para seguintes espécies: Aedes scapularis (Rondone, 1848) (p = 0,03651), Coquillettidia chrysonotum (Peryassu, 1922) (p = 0,00795), Mansonia fonsecai (Pinto, 1932) (p = 0,00804), e Runchomyia theobaldi Lane & Cerqueira, 1934 (p = 0,01996). Não houve correlação significativa com a abundância das principais espécies capturadas e as médias dos fatores abióticos avaliados. A taxa de paridade de Anopheles cruzii atingiu média percentual de 48%, não existindo correlação entre a abundância e a taxa de paridade. O crepúsculo exerce influência no comportamento apetente das espécies de Culicidae. A comparação de similaridade entre os crepúsculos apontou para elevada semelhança da composição específica. Anopheles cruzii atingiu dominância nos períodos vespertino e matutino, sendo a diversidade de forma geral reduzida nestes períodos.

Kerteszia subgenus of Anopheles associated with the Brazilian Atlantic rainforest:current knowledge and future challenges

BACKGROUND

The Atlantic rainforest ecosystem, where bromeliads are abundant, provides an excellent environment for Kerteszia species, because these anophelines use the axils of those plants as larval habitat. Anopheles (K.) cruzii and Anopheles (K.) bellator are considered the primary vectors of malaria in the Atlantic forest. Although the incidence of malaria has declined in some areas of the Atlantic forest, autochthonous cases are still registered every year, with Anopheles cruzii being considered to be a primary vector of both human and simian Plasmodium.

METHODS

Recent publications that addressed ecological aspects that are important for understanding the involvement of Kerteszia species in the epidemiology of malaria in the Atlantic rainforest in the Neotropical Region were analysed.

CONCLUSION

The current state of knowledge about Kerteszia species in relation to the Atlantic rainforest ecosystem was discussed. Emphasis was placed on ecological characteristics related to epidemiological aspects of this group of mosquitoes. The main objective was to investigate biological aspects of the species that should be given priority in future studies.

The second internal transcribed spacer of nuclear ribosomal DNA as a tool for Latin American anopheline taxonomy - a critical review

Among the molecular markers commonly used for mosquito taxonomy, the internal transcribed spacer 2 (ITS2) of the ribosomal DNA is useful for distinguishing among closely-related species. Here we review 178 GenBank accession numbers matching ITS2 sequences of Latin American anophelines. Among those, we found 105 unique sequences corresponding to 35 species. Overall the ITS2 sequences distinguish anopheline species, however, information on intraspecific and geographic variations is scarce. Intraspecific variations ranged from 0.2% to 19% and our analysis indicates that misidentification and/or sequencing errors could be responsible for some of the high values of divergence. Research in Latin American malaria vector taxonomy profited from molecular data provided by single or few field capture mosquitoes. However we propose that caution should be taken and minimum requirements considered in the design of additional studies. Future studies in this field should consider that: (1) voucher specimens, assigned to the DNA sequences, need to be deposited in collections, (2) intraspecific variations should be thoroughly evaluated, (3) ITS2 and other molecular markers, considered as a group, will provide more reliable information, (4) biological data about vector populations are missing and should be prioritized, (5) the molecular markers are most powerful when coupled with traditional taxonomic tools.

Intraspecific variation of second internal transcribed spacer of nuclear ribosomal DNA among populations of Anopheles (Kerteszia) cruzii (Diptera: Culicidae)

Anopheline species of the subgenus Kerteszia, including Anopheles (Kerteszia) cruzii Dyar & Knab (Diptera: Culicidae), are bromeliad-malaria vectors in the Atlantic rain forest of Brazil. Morphological, genetic, and molecular polymorphisms among different populations of An. cruzii have been reported, and it has been suggested that this taxon includes a complex of cryptic species. Specimens of An. cruzii were collected in the states of SHo Paulo and Santa Catarina, from locations where autochthonous malaria cases have been reported during the last decade. The second internal transcribed spacers (ITS2) of nuclear ribosomal DNA of the captured specimens were sequenced and compared with each other. Intraspecific ITS2 sequence polymorphisms were identified, and nucleotide divergence among specimens varied from 0.3 to 0.9%. The number of nucleotides in the ITS2 sequences of these mosquitoes varied from 327 to 334, and the CG contents varied from 61.7 to 62%. The data provide further indication of An. cruzii being a complex of cryptic species.

Variability and genetic differentiation among Anopheles (Ano.) intermedius Chagas, 1908 and Anopheles (Ano.) mattogrossensis Lutz & Neiva, 1911 (Diptera: Culicidae) from the Brazilian Amazon

Anopheles (Anopheles) intermedius and Anopheles (Ano.) mattogrossensis are Brazilian anopheline species belonging to the scarcely studied Anopheles subgenus. Few studies have been done on the genetic differentiation of these species. Both species have been found infected by Plasmodium and are sympatric with other anopheline species from the Nyssorhynchus subgenus. Eighteen enzymatic loci were analyzed in larval specimens of An. intermedius and An. mattogrossensis aiming to estimate the variability and genetic differentiation between these species. An. mattogrossensis population showed higher genetic variability (P = 44.4 and Ho = 0.081 +/- 0.031) than that of An. intermedius (P = 33.3 and Ho = 0.048 +/- 0.021). Most analyzed loci showed genotypic frequencies according to Hardy-Weinberg equilibrium, except for LAP1 and LAP2 in An. intermedius, and EST1 and PGM loci in An. mattogrossensis. The genetic distance between these species (D = 0.683) was consistent with the inter-specific values reported for Anopheles subgenus. We verified that the polymorphism and heterozygosity percentile values found in both species and compared to those in the literature, showed no relation between the level of isozyme variability and geographical distribution. The low variability found in these two species is probably more related to the niche they occupy than to their geographic distribution.