Initiation of primary cell cultures from embryos of the mosquitoes Anopheles albimanus and Aedes taeniorhynchus (Diptera: Culicidae)

Primary cell cultures were obtained from eggs of Anopheles albimanus and Aedes taeniorhynchus mosquitoes, vectors of human malaria and of Venezuelan equine encephalitis virus, respectively. The cellular growth of the An. albimanus cells began four weeks after explanting the embryonic tissues in MK/VP12 medium, supplemented with 15% fetal bovine serum. The culture showed heterogeneous cellular morphology. With regard to the Ae. taeniorhynchus culture, growth occurred three weeks after initiating the culture in MM/VP12 medium. The majority of cells were small and round. Karyotypes were examined in the latter species.

The identification of Anopheles (Nyssorhynchus) rondoni (Diptera: Culicidae) in Mato Grosso, Brazil: an analysis of key character variability

A morphological study was made of a population of Anopheles (Nyssorhynchus) rondoni (Neiva and Pinto) from northern Mato Grosso, Brazil. This population usually lacked the primary key character of a dark basal band on hindtarsomere 3, i.e., hindtarsomere 3 was all white as in most other members of the subgenus. It was determined that this species can be recognized instead by the presence of a dark spot on the thorax made up of a large dark prescutellar space that is contiguous with a concolorous central area on the scutellum. A secondary character of a dark area on the costa created by the fusion of the humeral dark, presector dark and sector dark proximal spots is also usually reliable. Regression analyses comparing the lengths and ratios of the dark bands on hindtarsomeres 2 to those on 3 describe a straight line relationship. This suggests that the "atypical" population is at one end of a character gradient. We propose that in the subgenus Nyssorhynchus individuals that have a long basal band on hindtarsomere 2 are more likely to also have a basal band on hindtarsomere 3. The pupal stage of this species has not been previously described. Reared-associated specimens from this study show that the pupa can be easily differentiated from all other Nyssorhynchus by the relatively stout, usually 2 or 3 branched (1-5), setae 1 and 5 on segments IV-VII.

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.

Life history correlates of adult size in the malaria vector Anopheles darlingi

Adult dry weights of laboratory-reared Anopheles darlingi were highly correlated with wing lengths, which were used to estimate size variation in natural populations of this species. Significant differences in mean wing lengths of females trapped at baits were detected among collections in the same week at one site, but not between three sites in Brazil and Boliva. Relatively higher variability of wing lengths, compared to collections of other Anopheles (Nyssorhynchus), and platykurtic size distributions in large, single-night collections suggested that An. darlingi females caught at baits emerged from heterogenous larval habitats. No relationship was detected between parous state and the body size of wild-caught females. Adult males and females of laboratory-reared An. darlingi did not differ in body size. This absence of sexual size dimorphism is rare among mosquitoes and has not been noted previously in the genus Anopheles.

Man-biting activity of Anopheles (Nyssorhynchus) albimanus and An. (Kerteszia) neivai (Diptera: Culicidae) in the Pacific Lowlands of Colombia

The daily man-biting activity of Anopheles (Nyssorhynchus) albimanus and An. (Kerteszia) neivai was determined in four ecologically distinct settlements of the Naya River, Department of Valle, Colombia. Differences were found among the settlements with respect to the mosquito species present, intradomiciliary and extradomiciliary biting activity and population densities.

Bionomics of Anopheles aquasalis Curry 1932, in Guaraí, state of Rio de Janeiro, southeastern Brazil: I. Seasonal distribution and parity rates

From a total of 12,721 anophelines collected in a lowland area in Guaraí, Rio de Janeiro, from November 1991 to October 1992, 99.7% (12,688) were Anopheles aquasalis. This species occurred throughout the year, but in higher numbers from April to September, when rainfall was low or moderate. The proportion of parous females in June was significantly higher than the annual rate. An. aquasalis was weakly attracted by a light-trap, and no significant differences in abundance were detected between nights with and without moonlight.

Biological variation in Anopheles darlingi root

Behavioural variation in the South American malaria vector Anopheles darlingi is described. At the centre of its distribution, in forest areas close to the city of Manaus, Brazil, it is primarily exophagic and exophilic. Mosquitoes from this area are chromosomally diverse. Towards the northern edge of its distribution (in Guyana and Venezuela) it is more endophagic and less diverse chromosomally. Similarly in the south (in the state of Minas Gerais) it is less polymorphic. In this area, however, it is primarily zoophilic and exophagic. Evidence is presented that female wing size may vary between populations. The possibility that this widely distributed species may be a complex could have important implications for future malaria control schemes.

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

Egg Structures of Anopheles fluminensis and Anopheles shannoni

Eggs of two species belonging to the Arribalzagia Series of the Laticorn Section of Anopheles (Anopheles) collected in Brazil are described from scanning electron micrographs. The An. fluminensis egg is long with shallow floats displaced far dorsally. The narrow deck region is overlain by a frill modified into prominent ridges that are nearly continuous to both ends of the egg. Slightly opened decks at both poles contain an average of four lobed tubercles. Polygonal, plastron-type chorionic cells cover the lateral and dorsal surfaces. The egg of An. shannoni is unique in possessing 22-27 fingerlike filaments that project with regular spacing from each of its massive floats. These filaments and their bases are highly perforated and are believed to trap air and support flotation of the egg with the dorsal surface up, contrary to the usual orientation for anophelines. The eggs are compared with those of related species bearing similar structures, notably An. fluminensis with An. mediopunctatus s.s and An. shannoni with An. peryassui

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

Anopheles aquasalis Eggs from Two Venezuelan Localities Compared by Scanning Electron Microscopy

Anopheles (Nyssorhynchus) aquasalis, is the main coastal vector of malaria from northeastern Venezuela to southeastern Brazil. Several authors have argued that An. aquasalis is a highly polymorphic species while others indicated that it is a complex of closely related species. This investigation compared the morphology of An. aquasalis eggs from Sinamaica (Zulia State) and Yaguaraparo (Sucre State), the west and east of Venezuela, respectively. We were able to separate eggs from the two localities using discriminant analyses based on ratios and percentages of anterior and posterior tubercles measured by scanning electron microscopy. The results of this work suggest that An. aquasalis has high intraspecific variation

Systematics and Population Level Analysis of Anopheles darlingi

A new phylogenetic analysis of the Nyssorhynchus subgenus (Danoff-Burg and Conn, unpub. data) using six data sets {morphological (all life stages); scanning electron micrographs of eggs; nuclear ITS2 sequences; mitochondrial COII, ND2 and ND6 sequences} revealed different topologies when each data set was analyzed separately but no heterogeneity between the data sets using the arn test. Consequently, the most accurate estimate of the phylogeny was obtained when all the data were combined. This new phylogeny supports a monophyletic Nyssorhynchus subgenus but both previously recognized sections in the subgenus (Albimanus and Argyritarsis) were demonstrated to be paraphyletic relative to each other and four of the seven clades included species previously placed in both sections. One of these clades includes both Anopheles darlingi and An. albimanus, suggesting that the ability to vector malaria effectively may have originated once in this subgenus. Both a conserved (315 bp) and a variable (425 bp) region of the mitochondrial COI gene from 15 populations of An. darlingi from Belize, Bolivia, Brazil, French Guiana, Peru and Venezuela were used to examine the evolutionary history of this species and to test several analytical assumptions. Results demonstrated (1) parsimony analysis is equally informative compared to distance analysis using NJ; (2) clades or clusters are more strongly supported when these two regions are combined compared to either region separately; (3) evidence (in the form of remnants of older haplotype lineages) for two colonization events; and (4) significant genetic divergence within the population from Peixoto de Azevedo (State of Mato Grosso, Brazil). The oldest lineage includes populations from Peixoto, Boa Vista (State of Roraima) and Dourado (State of São Paulo).

Ecology of mosquitoes (Diptera: Culicidae) in areas of Serra do Mar State Park, State of São Paulo, Brazil. II - Habitat distribution

The mosquito (Diptera: Culicidae) ecology was studied in areas of Serra do Mar State Park, State of São Paulo, Brazil. Systematized biweekly human bait collections were made three times a day, for periods of 2 or 3 h each, in sylvatic and rural areas for 24 consecutive months (January 1991 to December 1992). A total of 24,943 adult mosquitoes belonging to 57 species were collected during 622 collective periods. Aedes scapularis, Coquillettidia chrysonotum, Cq. venezuelensis, Wyeomyia dyari, Wy. longirostris, Wy. theobaldi and Wy. palmata were more frequently collected at swampy and at flooded areas. Anopheles mediopunctatus, Culex nigripalpus, Ae. serratus, Ae. fulvus, Psorophora ferox, Ps. albipes and the Sabethini in general, were captured almost exclusively in forested areas. An. cruzii, An. oswaldoi and An. fluminensis were captured more frequently in a residence area. However, Cx. quinquefasciatus was the only one truly eusynanthropic. An. cruzii and Ae. scapularis were captured feeding on blood inside and around the residence, indicating that both species, malaria and arbovirus vectors respectively, may be involved in the transmission of these such diseases in rural areas.

Variation in cuticular hydrocarbons among strains of the Anopheles gambiae sensu stricto by analysis of cuticular hydrocarbons using gas liquid chromatography of larvae

Cuticular hydrocarbons of larvae of individual strains of the Anopheles gambiae sensu stricto were investigated using gas liquid chromatography. Biomedical discriminant analysis involving multivariate statistics suggests that there was clear hydrocarbon difference between the Gambian(G3), the Nigerian (16CSS and, its malathion resistant substrain, REFMA) and the Tanzanian (KWA) strains. The high degree of segregation (95%) in hydrocarbons among the four strains investigated indicates that further analysis is needed to enable understanding of hydrocarbon variation in samples of An. gambiae especially from areas where these populations co-exist.