Identification of species related to Anopheles (Nyssorhynchus) albitarsis by random amplified polymorphic DNA-Polymerase chain reaction (Diptera: Culicidae)

Species-specific Random Amplified Polymorphic DNA-Polymerase chain Reaction (RAPD-PCR) markers were used to identify four species related to Anopheles (Nyssorhynchus) albitarsis Lynch-Arribàlzaga from 12 sites in Brazil and 4 in Venezuela. In a previous study (Wilkerson et al. 1995), which included sites in Paraguay and Argentina, these four species were designated "A", "B", "C" and "D". It was hypothesized that species A is An. (Nys.) albitarsis, species B is undescribed, species C is An. (Nys) marajoara Galvão and Damasceno and species D is An. (Nys.) deaneorum Rosa-Freitas. Species D, previously characterized by RAPD-PCR from a small sample from northern Argentina and southern Brazil, is reported here from the type locality of An. (Nys.) deaneorum, Guajará-Mirim, state of Rondônia, Brazil. Species C and D were found by RAPD-PCR to be sympatric at Costa Marques, state of Rondônia, Brazil. Species A and C have yet to be encountered at the same locality. The RAPD markers for species C were found to be conserved over 4,620 km; from Iguape, state of São Paulo, Brazil to rio Socuavo, state of Zulia, Venezuela. RAPD-PCR was determined to be an effective means for the identification of unknown species within this species complex.

Classification of immature stage habitats of Culicidae (Diptera) collected in Córdoba, Argentina

In order to classify mosquito immature stage habitats, samples were taken in 42 localities of Córdoba Province, Argentina, representing the phytogeographic regions of Chaco, Espinal and Pampa. Immature stage habitats were described and classified according to the following criteria: natural or artificial; size; location related to light and neighboring houses; vegetation; water: permanence, movement, turbidity and pH. Four groups of species were associated based on the habitat similarity by means of cluster analysis: Aedes albifasciatus, Culex saltanensis, Cx. mollis, Cx. brethesi, Psorophora ciliata, Anopheles albitarsis, and Uranotaenia lowii (Group A); Cx. acharistus, Cx. quinquefasciatus, Cx. bidens, Cx. dolosus, Cx. maxi and Cx. apicinus (Group B); Cx. coronator, Cx. chidesteri, Mansonia titillans and Ps. ferox (Group C); Ae. fluviatilis and Ae. milleri (Group D). The principal component analysis (ordination method) pointed out that the different types of habitats, their nature (natural or artificial), plant species, water movement and depth are the main characters explaining the observed variation among the mosquito species. The distribution of mosquito species by phytogeographic region did not affect the species groups, since species belonging to different groups were collected in the same region.

Culex (Culex) interfor Dyar (Diptera: Culicidae), morphological description including previously unknown life stages

The adult female and male and the pupal and larval stages of Culex (Culex) interfor Dyar are described and compared with those of Cx. bidens Dyar. Available data about distribution are presented.

Taxonomy and biology of Culex (Culex) maxi Dyar (Diptera: Culicidae) in South America

Culex (Culex) maxi Dyar is described in the adult, pupal and larval stages, and the male genitalia and parts of the fourth-instar larva are illustrated. The larva is described for the first time. The paper includes a summary of available information on the taxonomy, bionomics and distribution of the species. The taxonomy and identification of the species are reviewed in light of current knowledge of the subgenus Culex in the New World.

Winter biology of Culex pipiens quinquefasciatus say, (Diptera: Culicidae) from Córdoba, Argentina

Adult cohorts and immature stages were kept under field conditions during the autumn and winter of three consecutive years. Survival, oviposition and development time from egg to adult were considered. The adult cohorts were studied under three experimental conditions: unfed cohorts, cohorts fed with sugar solution ansd cohorts fed with both sugar solution and blood (chicken). Female longevity showed significant differences among the three treatments. Females of unfed cohorts lived up to three weeks; females fed with sugar solution survived until six weeks, while those fed both with sugar and blood lived at most fourteen weeks; after the blood intake eggs were laid. In the immature stages, the highest relative mortality rates occurred during the egg and larval stages. Total pre-adult mortality varied between 59.09 and 89.71%. The developmental duration from egg to adult was between 43-62 days; there were no differences among results obtained for the three years.

Establishment and Characterization of a Cell Line from the Mosquito Anopheles albimanus (Diptera: Culicidae)

A new cell line designated LSB-AA695BB, was established from embryos of the mosquito Anopheles albimanus. The primary culture was initiated in April, 1995, and the first passage was made 48 days later. Serial subcultures of the cells have been carried through 90 passages from Abril 1995 to February 1996. The cells were grown at 28°C in MK/VP12 medium, supplemented with 20% fetal bovine serum; the pH tolerance ranged between 6.8 to 7.0. The cells have also been adapted to MM/VP12 medium under the same pH, temperature and serum concentration. The majority of the cells were a fibroblast-type. Isozyme characterization showed a pattern similar to that of An. albimanus pupae and adults but distinct from Ae. taeniorhynchus and Ae. albopictus (C6/36) mosquito cell lines. The culture was shown to be free of mycoplasma, bacteria and fungi. Microsporidia contamination of transovarial transmission was controlled with 6.0 mg/ml of albendazole

Culex gnomatos a New Species of the Spissipes Section of Culex (Melanoconion) (Diptera: Culicidae) from the Amazon Region

The adult male and female of Culex (Melanoconion) gnomatos n. sp. are described and compared with Cx. vomerifer Komp, Cx. portesi Senevet & Abonnenc and Cx. sacchettae Sirivanakarn & Jakob. Available data about distribution and bionomics are presented

Description of the Immature Stages of Anopheles (Nyssorhynchus) rondoni (Neiva & Pinto) (Diptera: Culicidae)

The larval and pupal stages of Anopheles (Nyssorhynchus) rondoni (Neiva and Pinto) (Albimanus Section) are fully described and illustrated for the first time. The larval stage is similar to An. (Nys.) strodei Root. It can be recognized by the following combination of characters: clypeal index, 1.6-2.9; single, aciculate setae 2,3-C; seta 3-C 0.5-0.7 the length of 2-C; setae 1,2-P rarely sharing a common tubercle; seta 1-P with narrow leaflets. The pupal stage is distinguished from other Nyssorhynchus by having setae 1-IV-VII and 5-V-VII branched. Only minor variation was found in setal counts between specimens from Peixoto de Azevedo, State of Mato Grosso and Bocaina, State of São Paulo, Brazil

Estimation of Genetic Divergence and Gene Flow between Culex pipiens and Culex quinquefasciatus (Diptera: Culicidae) in Argentina

Allele frequencies at seven polymorphic loci controlling the synthesis of enzymes were analyzed in six populations of Culex pipiens L. and Cx. quinquefasciatus Say. Sampling sites were situated along a north-south line of about 2,000 km in Argentina. The predominant alleles at Mdh, Idh, Gpdh and Gpi loci presented similar frequencies in all the samples. Frequencies at the Pgm locus were similar for populations pairs sharing the same geographic area. The loci Cat and Hk-1 presented significant geographic variation. The latter showed a marked latitudinal cline, with a frequency for allele b ranging from 0.99 in the northernmost point to 0.04 in the southernmost one, a pattern that may be explained by natural selection (FST = 0.46; p < 0.0001) on heat sensitive alleles. The average value of FST (0.088) and Nm (61.12) indicated a high gene flow between adjacent populations. A high correlation was found between genetic and geographic distance (r = 0.83; p < 0.001). The highest genetic identity (IN = 0.988) corresponded to the geographically closest samples from the central area. In one of these localities Cx. quinquefasciatus was predominant and hybrid individuals were detected, while in the other, almost all the specimens were identified as Cx. pipiens. To verify the fertility between Cx. pipiens and Cx. quinquefasciatus from the northern- and southernmost populations, experimental crosses were performed. Viable egg rafts were obtained from both reciprocal crosses. Hatching ranged from 76.5 to 100%. The hybrid progenies were fertile through two subsequent generations

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 São 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.

The subgenus Dendromyia theobald: a review with redescriptions of four species (Diptera: Culicidae)

A morphological study of larval, pupal and adult life stages (including genitalia characters) was performed in order to evaluate the classification of the subgenus Dendromyia, genus Wyeomyia Theobald. Six species are included: Wy. ypsipola Dyar, Wy. jocosa (Dyar & Knab), Wy. testei Senevet & Abonnenc, Wy. complosa (Dyar), Wy. luteoventralis Theobald and Wy. trifurcata Clastrier, the first four of which are redescribed. The descriptions include illustrations of the male and female genitalia, fourth-instar larva and pupa. The result firmly supports Dendromyia as a monophyletic group, with well defined characters. Keys for the identification of all life stages of species included in Dendromyia are provided.

Vector competence of Culex quinquefasciatus say from different regions of Brazil to Dirofilaria immitis

The vector competence of Culex quinquefasciatus from five localities in Brazil to Dirofilaria immitis was evaluated experimentally. Females from each locality were fed on an infected dog (~ 6 microfilariae/µl blood). A sample of blood fed mosquitoes were dissected approximately 1 h after blood meal. These results demonstrated that all had ingested microfilariae (mean, 4.8 to 24.6 microfilariae/mosquito). Fifteen days after the infected blood meal, the infection and infective rates were low in all populations of Cx. quinquefasciatus. The mean number of infective larvae detected in the head and proboscis of these mosquitoes was 1-1.5. The vector efficiency, the number of microfilariae ingested/number of infective larvae, was low for all populations of Cx. quinquefasciatus. However, the survival rate for all populations was high (range 50-75%). The survival rate of Aedes aegypti assayed simultaneously for comparison was low (24.7%), while the vector efficiency was much higher than for Cx. quinquefasciatus. These data suggest that the vector competence of all assayed populations of Cx. quinquefasciatus to D. immitis in Brazil is similar and that this species is a secondary vector due to its low susceptibility. Nevertheless, vector capacity may vary between populations due to differences in biting frequency on dogs that has been reported in Brazil.

Environmental characteristics of the cemeteries of Buenos Aires City (Argentina) and infestation levels of Aedes aegypti (Diptera: Culicidae)

Cemeteries with many water-filled containers, flowers, sources of human blood, and shade are favorable urban habitats for the proliferation of Aedes aegypti, a vector of yellow fever and dengue. A total of 22,956 containers was examined in the five cemeteries of the city of Buenos Aires, Argentina. The vector was found in four cemeteries that showed an average infestation level of 5.5% (617 positive out of 11,196 water-filled containers). The four cemeteries positive for Ae. aegypti showed significantly different (p<0.01) infestation levels. Vegetation cover and percentage of infestation were significantly correlated (p<0.01), but neither cemetery area nor number of available containers were significantly related to the proportion of positive vases. Our results suggest that the cemeteries of Buenos Aires represent a gradient of habitat favorableness for this vector species, some of which may act as foci for its proliferation and dispersal.