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

Anopheles cruzii is a small sylvatic mosquito and primary human Plasmodium vector in Southern Brazil. The distribution of this bromeliad-breeding mosquito follows the Atlantic forest coastal distribution, where bromeliads are abundant. Morphological, genetic, and molecular polymorphisms among different populations have been reported and it has recently been suggested that An. cruzii is a complex of cryptic species. The aim of this work is to analyze the gene flow between different populations of An. cruzii collected in four localities within the geographic distribution range of the species, and to examine if An. cruzii is a complex of cryptic species. The genetic distances show that populations of the states of Santa Catarina, Sao Paulo, and Rio de Janeiro are genetically closer (0.032 to 0.083) than populations of Bahia (0.364 to 0.853) based on profiles from 10 distinct isoenzyme loci. The Fst was lower (0.077) when the Bahia population was excluded than when it was included (0.300) in the analyses. The inferred number of migrants per generation was 2.99 individuals among populations from the states of Santa Catarina, Sao Paulo, and Rio de Janeiro and 0.58 migrants per generation among all populations. Results suggest that An. cruzii is a complex of species and that the specimens of state of Bahia can be considered as belonging to a species that is distinct from other three closely-related populations studied.     

Role of Anopheles (Kerteszia) bellator as malaria vector in southeastern Brazil (Diptera: Culicidae)

New research concerning Anopheles bellator in the southeast of the State of S?o Paulo, Brazil, are reported. Adult females of this mosquito showed remarkable endophily and endophagy which was even greater than An. cruzii. The epidemiological role of this anopheline as a malaria vector is discussed.     

Changes in the fat body during the post-embryonic development of the predator Toxorhynchites theobaldi (Dyar & Knab) (Diptera: Culicidae)

Several studies have focused on understanding the biochemistry and morphology of the fat body of the hematophagous mosquito Aedes aegypti (L.) (Diptera: Culicidae). In contrast, few studies, if any, have focused on morphological characters of the fat body in other mosquitoes, especially non-hematophagous taxa such as the culicid Toxorhynchites. Larvae of Toxorhynchites prey upon the larvae of other mosquito species and are used in vector mosquito control. We investigated aspects of the fat body trophocytes, including the morphometric analyses of the lipid droplets, protein granules and nuclei, during Toxorhynchites theobaldi (Dyar & Knab) post-embryonic development. Following the body weight increase from larval stage L2 to L4, the size of lipid droplets within the trophocytes also increase, and are likely the result of lipogenesis. Lipid droplets decrease in size during L4 to the female pupal stage and increase once again during the period from newly-emerged to mature adult females. Protein granules are observed for the first time in female pupae, and their appearance might be related to protein storage during metamorphosis. The size of the nucleus of trophocytes also increases during larval development, followed by a decrease during metamorphosis and an additional increase as adult female ages. In conclusion, the morphology of the fat body of T. theobaldi changes according to the developmental stage. Our study provides for the first time important insights into T. theobaldi fat body development and contributes to understand this species biology.     

Occurrence of Toxorhynchites guadeloupensis (Dyar Knab) in oviposition trap of Aedes aegypti (L.) (Diptera: Culicidae)

Toxorhynchites guadeloupensis (Dyar Knab), a poorly known mosquito species, was observed preying upon Aedes aegypti (L.) larvae, in an oviposition trap placed for routine dengue entomological surveillance, during 2003-2004 in the urban area of Boa Vista, Roraima, Brazil. This is the first report for Tx. guadeloupensis using Ae. aegypti oviposition traps as breeding places. This finding may have important consequences in the epidemiology and local dengue control since Ae. aegypti density is a basic variable in dengue prediction. Whether predation of Ae aegypti by Tx. guadeloupensis in the Amazon is of significance, is a question to be examined. Also, larval predation may be a cause for underestimation of the actual Ae aegypti numbers. Together these hypotheses need to be better investigated as they are directly related to dengue epidemiology, to the success of any outbreak prediction and surveillance program.     

The structure of the male genitalia of Aedes diantaeus Howard, Dyar et Knab (Diptera, Culicidae)

The structure of the male genitalia of Aedes diantaeus was studied under scanning electron and optical microscopes. The tridimentional structure of the coxite is described and the structure of apical and basal warts and the arrangement of setae on the coxite are clarified. The structure of the claspette, i.e., the position of the claspette’s wing (filament) in relation to the claspette’s stem and also the shape and the structure of the wing were studied. The shape of the proctiger and the position of the paraprocts were investigated. A large membranous area forming paired lobes on the dorsal surface of the proctiger is described. Significant differences between Aedes diantaeus and A. caspius, A. cantans, and A. communis in the structure of the coxite, claspette, and proctiger, are demonstrated.     

A new species of Anopheles (Anopheles) from Namibia (Diptera: Culicidae)

Abstract. The adult, pupa, larva and egg of Anopheles {Anopheles) namibien-sis sp.n. from the Kavango district, Namibia (South West Africa), are described and comparisons made with Anopheles (Anopheles) ziemanni Griinberg. A photomap of the polytene chromosomes from the salivary glands of the fourth stage larvae is presented.     

Description of immature stages of Culex ocossa Dyar & Knab, Culex delpontei Duret and Culex pereyrai Duret of the Melanoconion subgenus (Diptera: Culicidae).

The larva and pupa of Culex (Melanoconion) ocossa Dyar & Knab are redescribed and those of Culex (Melanoconion) delpontei Duret and Culex (Melanoconion) pereyrai Duret are described from specimens collected in the states of S?o Paulo and Paraná, Brazil. The pupa of Cx. ocossa differs from those of the other two species in having seta 5-IV-VI dark with strongly aciculated branches, and caudolateral angle of segment VIII produced into sharp point, and seta 1-P present; Cx. delpontei can be distinguished from Cx. pereyrai in possessing paddle lightly tanned, trumpet flared, and wing and leg cases lightly tanned, without pattern of dark spots; Cx. pereyrai can be recognized by having wing case with pattern of dark, discontinuously pigmented, longitudinal lines, and trumpet cylindrical, not flared. The larvae of the three species share the presence of seta 2-C placed medially to seta 1-C.     

Cladistic analysis of the subgenus Anopheles (Anopheles) Meigen (Diptera: Culicidae) based on morphological characters

In the present study, we used morphological characters to estimate phylogenetic relationships among members of the subgenus Anopheles Meigen. Phylogenetic analyses were carried out for 36 species of Anopheles (Anopheles). An. (Stethomyia) kompi Edwards, An. (Lophopodomyia) gilesi (Peryassú), Bironella hollandi Taylor, An. (Nyssorhynchus) oswaldoi (Peryassú) and An. (Cellia) maculatus Theobald were employed as outgroups. One hundred one characters of the external morphology of the adult male, adult female, fourth-instar larva, and pupa were scored and analyzed under the parsimony criterion in PAUP. Phylogenetic relationships among the series and several species informal groups of Anopheles (Anopheles) were hypothesized. The results suggest that Anopheles (Anopheles) is monophyletic. Additionally, most species groups included in the analysis were demonstrated to be monophyletic.     

Satellite DNA of Anopheles stephensi liston (Diptera: Culicidae)

Four satellite DNAs in the Anopheles stephensi genome have been defined on the basis of their banding properties in Hoechst 33258-CsCl density gradients. Two of these satellites, satellites I and II, are visible on neutral CsCl density gradients as a light density peak forming approximately 15% of total cellular DNA. Hoechst-CsCl density gradient profiles of DNA extracted from polytene tissues indicates that these satellites are underreplicated in larval salivary gland cells and adult female Malpighian tubules and possibly also in ovarian nurse cells. The chromosomal location of satellite I on mitotic and polytene chromosomes has been determined by in situ hybridisation. Sequences complementary to satellite I are present in approximately equal amounts on a heterochromatic arm of the X and Y chromosomes and are also present, in smaller amounts, at the centromere of chromosome 3. A quantitative analysis of the in situ hybridisation experiments indicates that sequences complementary to satellite I at these two sites differ in their replicative behaviour during polytenisation: heterosomal satellite I sequences are under-replicated relative to chromosome 3 sequences in polytene larval salivary gland and ovarian nurse cell nuclei.     

Sequence analysis of the ribosomal DNA internal transcribed spacer 2 from populations of Anopheles nuneztovari (Diptera: Culicidae)

Sequence variation of the ribosomal DNA internal transcribed spacer 2 (ITS2) was examined for populations of the malaria vector Anopheles nuneztovari collected in Colombia, Venezuela, Bolivia, Suriname, and Brazil. Mosquitoes from Colombia and Venezuela had identical ITS2 sequences and were distinguished from sequences in other populations by three insertion/deletion events (indels) and by one transversion. The length of the ITS2 was 363-369 bp, and it had a G+C content of 55.3%- 55.7%. Variation in the length of the ITS2 between and within populations was due to indels in simple repeats. ITS2 consensus sequences were similar or identical for samples from the following three groups: (1) Colombia, Bolivia, and Venezuela; (2) Suriname and northern Brazil; and (3) eastern and central Brazil. The presence of two different consensus sequences from a single location near Manaus, Brazil, suggests that populations from eastern Brazil and those from Suriname converge in this region of the Amazon Basin. These data show that putative cryptic species of An. nuneztovari are distinguished by very minor differences in DNA sequence of the ITS2 region.      

Redescription of the neotropical Psychodidae (Diptera,Nematocera) described by Knab,Dyar and Coquillet

The remarkable neotropical Psychodidae described by Knab, Dyar and Coquillet, hitherto unrecognisable, are re-defined and figured from the type material. Lectotypes are selected, and affinities discussed.     

Karyotype of Brazilian Anopheles albitarsis sensu lato (Diptera:Culicidae)

Anopheles (Nyssorhynchus) albitarsis sensu lato is an important malaria vector in Brazil, especially in the Brazilian Amazon region. Chromosome preparations of fourth-instar larvae of A. albitarsis from Iranduba and Coari (AM) and Ilha Comprida (SP) were analyzed for karyotype determination and to improve cytogenetic identification of this species. Anopheles albitarsis possesses 2n = 6 chromosomes, with two pairs (submetacentric and metacentric) of autosomes and one pair of sex chromosomes, with X-Y dimorphism. The sex pair is homomorphic and acrocentric in females and heteromorphic in males, with a punctiform Y chromosome. Somatic pairing was detected in the prometaphase and metaphase chromosomes of the three A. albitarsis populations. Apparently, sex chromosome evolution in the Culicidae does not function as does evolution in the Culicidae, since it occurs in the subfamily Anophelinae, which possesses heteromorphic sex chromosomes and is regarded as primitive, based on several criteria. These karyotype data on the albitarsis complex reinforce the hypothesis that sex chromosome evolution in the subfamily Anophelinae is conserved, and the variation revealed in the mean size of chromosomes in three populations indicates that selective pressure in these populations is occurring only at a genetic level.     

Cytological differences and chromosomal rearrangements in four members of the Anopheles dirus complex (Diptera: Culicidae)

A reference photomap of the larval salivary gland, polytene chromosomes of the Anopheles dirus complex (species A) is presented. Samples of species A, B, C, and D from natural populations in Thailand were compared to this standard map using the larval progeny of wild-caught females. All species show differences in their chromosome banding patterns involving band size, number, and shape, particularly at the free ends of the X, 2R, and 2L. These differences provide useful diagnostic characters for separating members of the species complex. However, overall banding patterns are conservative in the group: species A, B, and C are virtually homosequential. Species D is highly polymorphic for a single paracentric inversion in each of the four autosomal arms and has a fixed inversion on the X chromosome. This same X chromosome inversion occurs at low frequency in species A.     

Geographic differentiation of life table attributes among Anopheles sacharovi (Diptera: Culicidae) populations in Turkey.

Biological data were compared under laboratory conditions for four local populations of the malaria vector, Anopheles sacharovi (Favre, 1903) in different ecological conditions at altitudes between 353 and 1,126 m in the Sanliurfa province of Turkey. No significant differences were found for complete development time from egg to adult among the populations and development times were not correlated with altitude. Based on cohorts of adults in each population, horizontal life tables were constructed. The average longevity was in the range of 15.19 +/- 0.69 to 21.86 +/- 1.04 days for adult females, which was longer than for adult males. No significant difference was found in life expectancy at emergence, e(x) when x = 1, between females and males in general (P > 0.05) in all populations. The net reproductive rate, R(o), was the highest for the SND population, while the rest of the populations showed very low reproductive rates independent of altitudinal effects. Populations that produced offspring earlier in life also produced more total female offspring, since the generation time, T(c), was negatively correlated with R(o) among the populations (r = -0.712, P < 0.05). Important parameters to explain the population growth, the intrinsic rate of increase, r(m) and birth rate, b, were found to be higher in the SND (0.13 and 0.30, respectively). Time required for the population to increase two-fold (doubling time, DT) was also significantly shorter in the SND population. Nineteen parameters in all life stages, both pre-adult and adult features of An. sacharovi, were used as physiological variables and these Operational Taxonomic Units were analyzed using Principal Component Analysis (PCA). Analyses confirmed results from the previous molecular studies that BRC and SND formed a distinct group from the other pair, PMK and GDK, along the first two principal components.     

Chromosomal polymorphism of populations of Anopheles arabiensis (Diptera: Culicidae) from Reunion island and cross-fertility among continental African populations

Cytological examination of a sample of Anopheles gambiae complex mosquitoes from Reunion island revealed the presence of An. arabiensis only. Chromosomal polymorphisms were observed only for inversion 3Ra, the standard homozygote form being predominant. Cross-mating experiments with laboratory specimens originating from continental Africa produced viable and fertile offspring with no chromosomal asynapsis observed in the F1 female progeny. There was no evidence for speciation of the Reunion island populations. The results are discussed with regard to the behaviour of the vector and its influence on the vectorial capacity of this species, and the history of malaria and malaria control in the South-West islands of the Indian Ocean and on Reunion island in particular.     

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 amosquito species that is involved in the transmission of malaria in Colombia, afterhaving been incriminated as such with epidemiological evidence from a malariaoutbreak in Cunday-Villarrica, Tolima. Subsequent morphological analyses of femalescaptured in the same place and at the time of the outbreak showed that the speciesresponsible for the transmission was not An. lepidotus, but ratherAnopheles pholidotus. However, the associated morphologicalstages and DNA sequences of An. pholidotus from the foci ofCunday-Villarrica had not been analysed. Using samples that were caught recently fromthe outbreak region, the purpose of this study was to provide updated and additionalinformation by analysing the morphology of female mosquitoes, the genitalia of malemosquitoes and fourth instar larvae of An. pholidotus, which wasconfirmed with DNA sequences of cytochrome oxidase I and rDNA internal transcribedspacer. A total of 1,596 adult females were collected in addition to 37 larvalcollections in bromeliads. Furthermore, 141 adult females, which were captured fromthe same area in the years 1981-1982, were analysed morphologically. Ninety-five DNAsequences were analysed for this study. Morphological and molecular analyses showedthat the species present in this region corresponds to An.pholidotus. Given the absence of An. lepidotus, even inrecent years, we consider that the species of mosquitoes that was previouslyincriminated as the malaria vector during the outbreak was indeed An.pholidotus, thus ending the controversy.