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PubMed2002

The eggs of Anopheles galvaoi and Anopheles evansae, two species of the subgenus Nyssorhynchus.

The ultrastructure of the eggs of Anopheles (Nyssorhynchus) galvaoi Causey, Deane, and Deane and Anopheles (Nyssorhynchus) evansae (Brethes) are described and illustrated with scanning electron micrographs. The eggs of these species are similar to those of Anopheles (Nyssorhynchus) aquasalis Curry, Anopheles (Nyssorhynchus) oswaldoi (Peryassu), and Anopheles (Nyssorhynchus) konderi Galvão and Damasceno in having floats long, widely joined posteriorly on the dorsal surface, the frill encircling the anterior end of the egg, and the crown absent. A few distinctive characters to distinguish An. evansae from An. galvaoi are given.

Animals↗
PubMed1997

Description of the eggs of Anopheles (Kerteszia) laneanus and Anopheles (Nyssorhynchus) antunesi (Diptera: Culicidae) by scanning electron microscopy.

The eggs of Anopheles laneanus Correa and Cerqueira and Anopheles antunesi Galvão and Amaral are described and illustrated with scanning electron micrographs. The egg of An. laneanus is compared with those of Anopheles cruzii Dyar and Knab and Anopheles bellator Dyar and Knab, and An. antunesi is compared with Anopheles lutzii Cruz and other Nyssorhynchus species.

Animals↗
PubMed2000

Evidence for mitochondrial introgression between Anopheles bwambae and Anopheles gambiae.

There is evidence for introgression between the malaria vectors Anopheles gambiae and Anopheles arabiensis, which belong to the Anopheles gambiae complex. Here we consider their relationship to another member of the complex, Anopheles bwambae. Species identifications were made using rDNA-PCR and revealed one An. bwambae/gambiae hybrid among 459 wild-caught mosquitoes. A 237-nucleotide region of the mitochondrial ND5 gene was sequenced in sixty-nine individuals. The results suggest that there is an An. bwambae specific group of haplotypes. However, two An. bwambae individuals carried haplotypes typical of An. gambiae and An. arabiensis. This is the first evidence for introgression between An. bwambae and other species of the An. gambiae complex and suggests that introgression may be more widespread, also occurring between other members of the complex.

Animals↗
PubMed2000

Differential ecology of Anopheles punctulatus and three members of the Anopheles farauti complex of mosquitoes on Guadalcanal, Solomon Islands, identified by PCR-RFLP analysis.

From a series of larval collections made across northern Guadalcanal during the dry season, October-November 1997, four members of the Anopheles punctulatus group of mosquitoes (Diptera: Culicidae) were identified using PCR-RFLP analysis. Anopheline larvae were found in 54/57 (95%) of the sites sampled, comprising An. farauti Laveran sensu stricto (32 sites), An. farauti species no. 2 (39 sites), An. farauti no. 7 (36 sites) and An. punctulatus Dönitz (10 sites). Anopheles punctulatus occurred only on the coastal plain, where it was associated with the more transient sites. Anopheles farauti sensu lato was more widespread throughout the survey region, with similar proportions of all three sibling species in both transient and permanent sites. Two members of the An. farauti complex, An. farauti s.s. and species no. 2, were found in brackish water. All breeding sites of An. punctulatus were cohabited by An. farauti s.l., sometimes by all three sibling species. Anopheles farauti s.s. was the only species collected on human bait, with a much higher biting rate early in the evening (57 bites/human/hour at 18.30-20.00 hours) than later (0.8 bites/human/hour at 21.00-24.00 hours).

Animals↗
PubMed1999

Anopheles (Anopheles) forattinii: a new species in Series Arribalzagia (Diptera: Culicidae).

Anopheles (Anopheles) forattinii new species, a member of the Series Arribalzagia, is described with illustrations of the larval and pupal stages, and male and female genitalia. It is contrasted with 2 similar species, An. (Anopheles) costai Fonseca & Ramos and An. (Anopheles) mediopunctatus (Lutz). This species, and An. costai, occur over much of South America where both have been misidentified as An. mediopunctatus, a species presently only known from southeastern Brazil.

Animals↗
PubMed2004

Natural Plasmodium infections in Anopheles darlingi and Anopheles benarrochi (Diptera: Culicidae) from eastern Peru.

Malaria, both Plasmodium falciparum (Welch) and Plasmodium vivax (Grassi & Feletti), has reemerged as a significant public health disease issue in Peru, especially in forested areas in the eastern part of the country. The spread of Anopheles darlingi Root, the principal South American malaria vector, into new areas of Peru is thought to be a factor in this resurgence. However, epidemiological evidence suggests that in malaria endemic areas of eastern Peru where An. darlingi does not occur, other species are involved in malaria transmission. The objective of this study was to analyze Anopheles species collected from 11 provinces within four departments in eastern Peru during 2001 and 2002 for infections with P. falciparum and P. vivax. More than 84,000 Anopheles mosquitoes representing 13 species were tested by enzyme-linked immunosorbent assay for the presence of Plasmodium circumsporozoite (CS) proteins. Of these, only An. darlingi and Anopheles benarrochi Gabaldón, Cova García & López were found positive. In total, 14 (0.98%) of 1,432 pools of An. darlingi were positive for Plasmodium species; specifically 10 (0.70%) pools were positive for P. falciparum, two (0.14%) were positive for P. vivax VK210, and two (0.14%) were positive for P. vivax VK247 proteins. Nine (0.14%) of 6,323 pools of An. benarrochi were positive for Plasmodium; five (0.08%) of 6,323 pools were positive for P. falciparum, two (0.03%) were positive for P. vivax VK247, one (0.02%) was positive for mixed P. vivax VK210/VK247 infections, and one (0.02%) was positive for mixed P. falciparum and P. vivax VK210 CS-proteins. Although infection rates in An. benarrochi were significantly lower (0.14%) than rates found for An. darlingi (0.98%), our data suggest that An. benarrochi may play a role in transmitting and maintaining Plasmodium species in various malaria endemic areas of eastern Peru.

Animals↗
PubMed2001

Confirmation of Anopheles varuna in vietnam, previously misidentified and mistargeted as the malaria vector Anopheles minimus.

Malaria control programs in Southeast Asia are faced with several questions concerning vector behavior and species identification, which need to be answered to consolidate and further improve the results of control practices. The vector system in Southeast Asia is complex because of the number of species potentially involved in malaria transmission. Additionally, the follow-up and evaluation of preventive control measures are hampered by the misidentification of vectors due to overlapping morphological characters of the female mosquitoes. In central Vietnam, control practices are aimed at 2 main species, Anopheles dirus s.l. and Anopheles minimus s.l. These reputed vectors were studied in an area of Binh Thuan Province of south-central Vietnam. Different collection methods were used to capture mosquitoes quarterly during a 1-year period. Mosquitoes were identified in the field and later subjected to detailed morphological examination and polymerase chain reaction-restriction fragment length polymorphism analysis. What was thought to be an unusual morphotype of An. minimus was shown to be Anopheles varuna, and most specimens identified as the former species in the field proved to be the latter species. Very few An. minimus individuals were found during the study period. The population of An. varuna was found to be highly zoophilic, and based on this behavior, it cannot be considered a vector in Vietnam. Because this species was previously being misidentified as An. minimus, a nonvector was mistargeted as a malaria vector in Binh Thuan Province. Anopheles dirus, which was found positive for Plasmodium falciparum circumsporozoite via enzyme-linked immunosorbent assay, is clearly the main vector in this area. Despite the fact that several potential secondary vectors were found during the study, the primary target for vector control in the region should be An. dirus.

Animals↗
PubMed1995

Metaphase karyotypes of Anopheles of Thailand and Southeast Asia: IV. The Barbirostris and Umbrosus species Groups, subgenus Anopheles (Diptera: Culicidae).

Metaphase karyotypes of 2 and 3 species of the Umbrosus and the Barbirostris Groups, respectively, of the subgenus Anopheles occurring in Thailand and Indonesia show inter- and intraspecific differences with respect to the amount and distribution of constitutive heterochromatin in the sex chromosomes and/or autosomes. Four forms of metaphase karyotypes have been recognized in the wild samples of Anopheles barbirostris based on differences in size and shape of X and Y chromosomes. It is not known whether forms A, B, and C of the metaphase karyotype of An. barbirostris found in Thailand represent inter- or intraspecific differences. However, form D, which occurs only in Indonesia, may represent a mitotic karyotype of a distinct species closely related to An. barbirostris. Anopheles campestris and An. barbumbrosus are each readily separated from An. barbirostris by mitotic chromosomes. Anopheles umbrosus and An. letifer of the Umbrosus Group also exhibit heterochromatin variation in the X chromosomes. These 2 species can be readily distinguished by the gross morphology of mitotic karyotypes, particularly the X and Y chromosomes.

Animals↗
PubMed2005

Identification and expression of odorant-binding proteins of the malaria-carrying mosquitoes Anopheles gambiae and Anopheles arabiensis.

Host preference and blood feeding are restricted to female mosquitoes. Olfaction plays a major role in host-seeking behaviour, which is likely to be associated with a subset of mosquito olfactory genes. Proteins involved in olfaction include the odorant receptors (ORs) and the odorant-binding proteins (OBPs). OBPs are thought to function as a carrier within insect antennae for transporting odours to the olfactory receptors. Here we report the annotation of 32 genes encoding putative OBPs in the malaria mosquito Anopheles gambiae and their tissue-specific expression in two mosquito species of the Anopheles complex; a highly anthropophilic species An. gambiae sensu stricto and an opportunistic, but more zoophilic species, An. arabiensis. RT-PCR shows that some of the genes are expressed mainly in head tissue and a subset of these show highest expression in female heads. One of the genes (agCP1588) which has not been identified as an OBP, has a high similarity (40%) to the Drosophila pheromone-binding protein 4 (PBPRP4) and is only expressed in heads of both An. gambiae and An. arabiensis, and at higher levels in female heads. Two genes (agCP3071 and agCP15554) are expressed only in female heads and agC15554 also shows higher expression levels in An. gambiae. The expression profiles of the genes in the two members of the Anopheles complex provides the first step towards further molecular analysis of the mosquito olfactory apparatus.

Amino Acid Sequence↗
PubMed2003

The dynamics of interactions between Plasmodium and the mosquito: a study of the infectivity of Plasmodium berghei and Plasmodium gallinaceum, and their transmission by Anopheles stephensi, Anopheles gambiae and Aedes aegypti.

Knowledge of parasite-mosquito interactions is essential to develop strategies that will reduce malaria transmission through the mosquito vector. In this study we investigated the development of two model malaria parasites, Plasmodium berghei and Plasmodium gallinaceum, in three mosquito species Anopheles stephensi, Anopheles gambiae and Aedes aegypti. New methods to study gamete production in vivo in combination with GFP-expressing ookinetes were employed to measure the large losses incurred by the parasites during infection of mosquitoes. All three mosquito species transmitted P. gallinaceum; P. berghei was only transmitted by Anopheles spp. Plasmodium gallinaceum initiates gamete production with high efficiency equally in the three mosquito species. By contrast P. berghei is less efficiently activated to produce gametes, and in Ae. aegypti microgamete formation is almost totally suppressed. In all parasite/vector combinations ookinete development is inefficient, 500-100,000-fold losses were encountered. Losses during ookinete-to-oocyst transformation range from fivefold in compatible vector parasite combinations (P. berghei/An. stephensi), through >100-fold in poor vector/parasite combinations (P. gallinaceum/An. stephensi), to complete blockade (>1,500 fold) in others (P. berghei/Ae. aegypti). Plasmodium berghei ookinetes survive poorly in the bloodmeal of Ae. aegypti and are unable to invade the midgut epithelium. Cultured mature ookinetes of P. berghei injected directly into the mosquito haemocoele produced salivary gland sporozoites in An. stephensi, but not in Ae. aegypti, suggesting that further species-specific incompatibilities occur downstream of the midgut epithelium in Ae. aegypti. These results show that in these parasite-mosquito combinations the susceptibility to malarial infection is regulated at multiple steps during the development of the parasites. Understanding these at the molecular level may contribute to the development of rational strategies to reduce the vector competence of malarial vectors.

Aedes↗
PubMed2003

Semipermeable species boundaries between Anopheles gambiae and Anopheles arabiensis: evidence from multilocus DNA sequence variation.

Attempts to reconstruct the phylogenetic history of the Anopheles gambiae cryptic species complex have yielded strongly conflicting results. In particular, An. gambiae, the primary African malaria vector, is variously placed as a sister taxon to either Anopheles arabiensis or Anopheles merus. The recent divergence times for members of this complex complicate phylogenetic analysis, making it difficult to unambiguously implicate interspecific gene flow, versus retained ancestral polymorphism, as the source of conflict. Using sequences at four unlinked loci, which were determined from multiple specimens within each of five species in the complex, we found contrasting patterns of sequence divergence between the X chromosome and the autosomes. The isolation model of speciation assumes a lack of gene flow between species since their separation. This model could not be rejected for An. gambiae and An. arabiensis, although the data fit the model poorly. On the other hand, evidence from gene trees supports genetic introgression of chromosome 2 inversions between An. gambiae and An. arabiensis, and also points to more broad scale genetic exchange of autosomal sequences between this species pair. That such exchange has been relatively recent is suggested not only by the lack of fixed differences at three autosomal loci but also by the sharing of full haplotypes at two of the three loci, which is in contrast to several fixed differences and considerably deeper divergence on the X. The proposed acquisition by An. gambiae of sequences from the more arid-adapted An. arabiensis may have contributed to the spread and ecological dominance of this malaria vector.

Animals↗
PubMed1993

Diel oviposition periodicity of anopheline mosquitoes (Diptera: Culicidae) from the Americas: Anopheles albimanus Wieldemann and Anopheles freeborni Aitken.

The diel oviposition patterns of Anopheles albimanus and An. freeborni derived from Panama and California, U.S.A., respectively, were studied in the laboratory by recording the egg-laying of individuals and colonies at 2-h intervals. Anopheles freeborni oviposition patterns were almost exclusively nocturnal, with 80% of eggs being laid during the scotophase. A large, well-defined peak of oviposition, comprising about 70% of eggs laid, occurred 4-6 h before sunrise. Anopheles albimanus oviposition patterns were bimodal with crepuscular and nocturnal components, 68% of eggs being laid shortly before lights went 'off' or 'on' and 32% during the scotophase. A small, well-defined peak of oviposition, comprising about 42% of eggs laid, occurred immediately following lights off (i.e. 18.00-20.00 hours). Nulliparous females allowed to engorge on human blood matured, on average, 104 follicles (range 80-142) for An. albimanus and 114 follicles (range 31-201) for An. freeborni.

Animals↗
PubMed2005

Species and populations of the Anopheles gambiae complex in Cameroon with special emphasis on chromosomal and molecular forms of Anopheles gambiae s.s.

We studied the geographical distribution of species, chromosomal, and molecular forms of the Anopheles gambiae Giles (Diptera: Culicidae) complex in 23 sites in Cameroon, Central Africa. Almost all the specimens collected in the four northern-most arid sites were Anopheles arabiensis. Anopheles melas was found in a rural locality surrounded by mangrove swamps, on the Atlantic Coast. In total, 1,525 An. gambiae s.s. females were identified down to their molecular form, and inversion polymorphisms on polytene chromosomes were scored from 186 half-gravid females. The Forest chromosomal form, with standard arrangements almost fixed on both arms of chromosome-2, was the only one observed in the southern, more humid localities. Karyotypes typical of Savanna and Mopti were recorded northwards, in the humid savannas of the Adamawa Province. The molecular forms M and S were widespread throughout Cameroon, and assort independently from the chromosomal forms. S-form populations were characterized by karyotypes typical of Forest and Savanna chromosomal forms, and M-form populations were characterized by karyotypes typical of Forest, Savanna, and Mopti. No M/S hybrid patterns were detected, although M and S mosquitoes were sympatric in 15 sites, providing further evidence for positive assortative mating within molecular forms. The observed ecogeographical distribution of M and S was peculiar: the ecological parameters involved in this distribution still need to be clarified as well as the possible role of competitive exclusion between chromosomally homosequential molecular forms. No difference was observed in host preference or in Plasmodium falciparum infection rates between sympatric M and S populations.

Animals↗
PubMed2005

An Anopheles gambiae salivary gland promoter analysis in Drosophila melanogaster and Anopheles stephensi.

Regulatory regions driving gene expression in specific target organs of the African malaria vector Anopheles gambiae are of critical relevance for studies on Plasmodium-Anopheles interactions as well as to devise strategies for blocking malaria parasite development in the mosquito. In order to identify an appropriate salivary gland promoter we analysed the transactivation properties of genomic fragments located just upstream of the An. gambiae female salivary gland-specific genes AgApy and D7r4. An 800 bp fragment from the AgApy gene directed specific expression of the LacZ reporter gene in the salivary glands of transgenic Anopheles stephensi. However, expression levels were lower than expected and the transgene was expressed in the proximal-rather than in the distal-lateral lobes of female glands. Surprisingly, a promoter fragment from the D7r4 gene conferred strong tissue-specific expression in Drosophila melanogaster but only low transcription levels in transgenic An. stephensi. These results imply a certain conservation of gland-specific control elements between the fruit fly and the mosquito suggesting that an increased degree of complexity, probably connected to the evolution of haematophagy, underlies the regulation of tissue-specific expression in mosquito female salivary glands.

Animals↗
PubMed2006

Effect of Novaluron (Rimon 10 EC) on the mosquitoes Anopheles albimanus, Anopheles pseudopunctipennis, Aedes aegypti, Aedes albopictus and Culex quinquefasciatus from Chiapas, Mexico.

Dengue fever is a serious problem in Mexico and vector control has not been effective enough at preventing outbreaks. Malaria is largely under control, but it is important that new control measures continue to be developed. Novaluron, a novel host-specific insect growth regulator and chitin synthesis inhibitor, has proved to be effective against agricultural pests, but its efficacy against larval mosquito vectors under field conditions remains unknown. In accordance with the World Health Organization Pesticide Evaluation Scheme, phase I, II and III studies were conducted to evaluate the efficacy and residual effect of Novaluron (Rimon 10 EC, Makhteshim, Beer-Sheva, Israel) on the malaria vectors Anopheles albimanus Wiedemann (Diptera: Culicidae) and Anopheles pseudopunctipennis Theobald, the dengue vectors Aedes aegypti (L) and Aedes albopictus Skuse and the nuisance mosquito Culex quinquefasciatus Say. Laboratory susceptibility tests yielded diagnostic concentrations for all five target species. Field trials to identify the optimum field dosage of Novaluron against Anopheles mosquitoes were carried out under semi-natural conditions in artificial plots and in vessels with wild mosquitoes. Efficacy was measured by monitoring mortality of larvae and pupae and the percentage of inhibition of emergence from floating cages. Dosages of Novaluron for field tests were based on pupal LC(99) (lethal concentration 99%) of An. pseudopunctipennis (0.166 mg/L) in plots and average pupal LC(99) of Ae. aegypti and Ae. albopictus (0.55 mg/L). At all dosages tested, Novaluron significantly reduced larval populations of An. albimanus, Culex coronator Dyar & Knab, Ae. albopictus and Cx. quinquefasciatus by approximately 90%, inhibited adult emergence of An. albimanus and An. pseudopunctipennis by approximately 97% for almost 4 months in experimental plots, and inhibited adult emergence of Ae. aegypti and Ae. albopictus by approximately 97% for up to 14 weeks. Recommended dosages of Novaluron for non-container breeding and container breeding mosquitoes are 0.166 mg/L and 0.55 mg/L, respectively. Overall, the residual effect was more sustained than that of temephos. The lowest dosage of Novaluron had less of an impact on non-target organisms than did temephos. Small-scale field trials in natural breeding sites treated with Novaluron at 0.6 L/ha eliminated adult emergence of An. albimanus and Cx. coronator for 8 weeks. For phase III studies, Novaluron was tested at the local and village levels, applying the optimum field rate to all natural breeding habitats within 1 km of a pair of neighbouring villages. Village-scale trials of Novaluron at 0.6 L/ha reduced An. albimanus larval populations for at least 8 weeks and, more importantly, sharply reduced the densities of adult host-seeking mosquitoes approaching houses. We conclude that Novaluron is effective and environmentally safer than temephos.

Animals↗
PubMed2005

First collection of Anopheles (Anopheles) punctipennis (Say) on Oahu, Hawaii: implications for the potential introduction of West Nile virus.

A single adult female of Anopheles (Anopheles) punctipennis (Say) was collected in a New Jersey light trap in the port area of Honolulu, Oahu, HI, on December 8, 2003. This is the 1st record of a wild-collected, intact Anopheles mosquito, and the 1st detection of An. punctipennis in the Hawaiian Islands. Extensive larval surveillance and additional light trapping in the area of the collection site indicate that populations of this species have not become established on Oahu. The distribution of An. punctipennis largely coincides with the distribution of West Nile virus (WNV) in North America. Although An. punctipennis is not an important vector of WNV, Culex quinquefasciatus and Cx. tarsalis are important vectors of WNV and occur in areas of North America with active WNV transmission. Culex quinquefasciatus is established in Hawaii, and Cx. tarsalis has been detected on multiple occasions by quarantine. Increased quarantine inspections, disinsection of airline cargo holds, enhanced vector surveillance, and the development of sanitary corridors around airports and port facilities are necessary to reduce the introduction of vectors and pathogens.

Animals↗
PubMed2005

Habitats and distribution of Anopheles sinensis and associated Anopheles hyrcanus group in Japan.

Mosquito collections were carried out in August 2002 and July 2003 in Japan. Anopheles sinensis of the Hyrcanus Group, Myzomyia Series of Anopheles, was the most common species encountered. The distribution and habitats of 5 Anopheles Hyrcanus Group species are included. Eight species belonging to Aedes, Culex, and Uranotaenia were found associated with An. sinensis in rice paddies and a variety of other larval habitats.

Animals↗
PubMed2006

Biting patterns and seasonal densities of Anopheles mosquitoes in the Cayo District, Belize, Central America with emphasis on Anopheles darlingi.

The present study utilized an experimental hut to conduct human-baited landing collections for characterizing the all-night biting patterns and seasonal densities of adult Anopheles darlingi in the centrally located Cayo District of Belize, Central America. A total of 25 all-night collections (i.e., sunset to sunrise) were conducted from January 2002 to May 2003, capturing a total of 18,878 An. darlingi females. Anopheles darlingi exhibited a bimodal nightly biting pattern with one predominate peak occurring three h after sunset and a smaller peak occurring one h prior to sunrise. Biting females were collected throughout the night in higher densities indoors (9,611) than outside (9,267) the experimental hut (O:I=1.00:1.04). Seasonal adult collections show An. darlingi densities were highest during the transitional months between the end of the wet and beginning of the dry season (January) and the end of the dry season and beginning of the wet season (May). A total of 2,010 An. darlingi females was captured in 31 two-h, human-baited landing collections performed from January to October 2002. Anopheles darlingi monthly population densities were found to have no significant associations with high or low temperatures, precipitation, or river level. However, qualitative data examination indicates an inverse relationship between river level and An. darlingi adult collections suggesting a disturbance of larval habitats. All-night biting and seasonal distribution patterns for other anopheline species are also described. None of the adult specimens collected throughout the entire study tested positive for Plasmodium spp. infection using the VecTest rapid diagnostic kit.

Animals↗