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At least 19 recordsLinked to original sources
PubMed1990

[Comparative studies on the role of Anopheles anthropophagus and Anopheles sinensis in malaria transmission in China].

This paper reports on the studies of the role of Anopheles anthropophagus and Anopheles sinensis in malaria transmission in a sense to elucidate which one of the two species the predominance in this respect. Systematic investigations including artificial infection of mosquitoes, quantitative entomological studies and parasitological research were conducted in 1982-1987 in 5 pilot areas in Anhui (1), Guangxi (2), Sichuan (1) and Guangdong (1). The results revealed that the susceptibility of An. anthropophagus to Plasmodium falciparum was significantly higher than that of An. sifefsis. The oocyst rate and sporozoite rate of the former were 27.9% and 10.9%, while those of the latter being 11.3% and 3.0%. Significant difference in natural infection rate of the two species was also observed. The mean sporozoite rate of An. anthropophagus was 0.58% (105/17984), and that of An. sinensis was 0.02% (4/17718). Taking several essential parameters (man-biting rate, human blood index, vectorial capacity and entomological inoculation rate) into consideration, the role of An. anthropophagus in malaria transmission was 20 times more vigorous than that of An. sinensis. The malaria incidence and parasite rate of the inhabitants in site were closely related to the proportion of An. anthropophagus in human dwellings. According to the survey pursued in 1983; An. anthropophagus was the major vector playing an important role in the outbreak of vivax malaria in Shenzhen. The preceding results disclosed the important role of Anopheles anthropophagus in the transmission of falciparum and vivax malaria. The findings are of significance in the stratification of malaria endemic areas of the country and the analysis of current situation and programming malaria control measures as well.

Animals↗
PubMed1991

Species-diagnostic differences in a ribosomal DNA internal transcribed spacer from the sibling species Anopheles freeborni and Anopheles hermsi (Diptera:Culicidae).

Approximately 460 base pairs (bp) of DNA sequence that included the second internal transcribed spacer (ITS2) and some flanking 5.8S and 28S ribosomal RNA coding regions were compared between the two closely related and morphologically indistinguishable mosquito species Anopheles freeborni and A. hermsi and a third related species, A. occidentalis. Sequences were determined from 14 clones of polymerase chain reaction (PCR)-amplified DNA obtained from four colonies of A. freeborni, two colonies of A. hermsi, and one individual A. occidentalis. Four clones showed independent single bp differences from the consensus for the relevant species. Eleven sites differed between the consensus sequences of A. hermsi and A. freeborni; 28 sites differed between A. hermsi and A. occidentalis. With the exception of a single bp mismatch in the 5.8S and two single bp mismatches near the undetermined junction of the ITS2 and 28S regions, all differences were confined to the ITS2 region. A PCR-based species-diagnostic assay for the cryptic species A. hermsi and A. freeborni was developed; it uses four synthetic oligonucleotides, two derived from areas of interspecies sequence difference in the ITS2, and two derived from highly conserved regions in the flanking coding sequences. Small amounts of mosquito DNA amplified in the presence of these four primers produce fragments of diagnostic size for each species: 900 bp for A. freeborni, 350 bp for A. hermsi, and approximately 1.2-1.4 kb for various other Anopheles species tested. We believe that this general approach to the development of species-diagnostic assays can be extended easily to other complexes of closely related, morphologically indistinguishable species.

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PubMed1992

[DNA probe for identification of sibling species of Anopheles sinensis and Anopheles anthropophagus].

Genomic DNA libraries of Anopheles sinensis and Anopheles anthropophagus were constructed. The positive clones suitable for discrimination sibling species of An. sinensis and An. anthropophagus were screened and a clone from An. sinensis DNA library was selected and the insert DNA was used as a DNA probe to test dot blot of genomic DNA from An. sinensis and An. anthropophagus. The results showed that the DNA probe hybridized with all stages of An. sinensis DNA, but had very weak hybridization signal with An. anthropophagus DNA. The probe was very sensitive and could detect as little as 7.5ng An. sinensis which represents approximately one-150th part of the total DNA from single mosquito. The results demonstrated that the DNA probe reported here could be used to distinguish species of An.sinensis from An. anthropophagus.

Animals↗
PubMed1990

[Restriction fragment length differences (RFLDs) of genomic DNA from different geographical strains of Anopheles sinensis and Anopheles anthropophagus].

Total DNA was extracted from three geographical strains of Anopheles sinensis and two geographical strains of Anopheles anthropophagus and digested respectively with three restriction endonucleases (Bgl II, Hae III and Pst I). The restriction fragment length differences (RFLDs) of repetitive DNA detected after agarose gel electrophoretic separation and ethidium bromide staining were compared among the above-mentioned geographical strains of both An. sinensis and An. anthropohagus. The results indicated that the band patterns are species- specific and strain-specific, their main bands being similar while their minor bands being distinctly different. Pst I digestion produced unique fragments for three geographical strains of An. sinensis while Bgl II digestion produced unique fragments for two geographical strains of An. anthropophagus. In view of the variation in repetitive DNA of different geographical strains of both An. sinensis and An. anthropophagus presented, the RFLDs could be used as a means to distinguish various closely related geographical strains of anopheline mosquitoes.

Animals↗
PubMed1978

Co-existence and attempted hybridization between Anopheles litoralis (King) and Anopheles sundaicus (Rodenwaldt) in Sabah, Malaysia.

Anopheles (Cellia) litoralis King and Anopheles (Cellia) sundaicus Rodenwaldt, vectors of malaria, were collected from the same brackis and sea-water habitats in six localities in Sabah. They share the same breeding habitats with predominance of one species over the other. The two species although distinct have small morphological differences and are taxonomically separated by certain wing characters. Hybridization between the two species was successful. Reciprocal crosses produced viable progeny which appeared to develop normally to adults. Hybridized females laid fewer viable eggs in comparison with the parents. The F1 hybrids resembled the litoralis parent in most characters. Backcrosses of both litoralis and sundaicus parents with the F1 hybrids yielded no eggs. F1 male hybrids were thus assumed to be sterile. The results obtained from cross matings between the two species suggested something more than subspecific status.

Animals↗
PubMed1991

Quantitation of Plasmodium falciparum sporozoites transmitted in vitro by experimentally infected Anopheles gambiae and Anopheles stephensi.

The frequency and numbers of Plasmodium falciparum sporozoites transmitted in vitro and corresponding sporozoite loads were determined for experimentally infected Anopheles gambiae and An. stephensi. Geometric mean (GM) sporozoite loads in three experiments ranged from 808 to 13, 905 for An. gambiae and from 6, 608 to 17, 702 for An. stephensi. A total of 44.1% of 68 infected An. gambiae and 49.2% of 63 infected An. stephensi transmitted sporozoites in vitro. The GM number of sporozoites transmitted was 4.5 for An. gambiae and 5.4 for An. stephensi. Overall, 86.9% of the mosquitoes transmitted from one to 25 sporozoites, and only 6.6% transmitted over 100 sporozoites (maximum = 369). Sporozoite loads were not a useful predictor of potential sporozoite transmission. Despite higher sporozoite loads, the numbers of sporozoites transmitted in vitro by the experimentally infected mosquitoes were similar to estimates obtained, using the same techniques, for naturally infected An. gambiae in western Kenya. The low but highly variable numbers of sporozoites transmitted in vitro by mosquitoes used in malaria vaccine challenge studies appears to be a reasonable simulation of natural sporozoite transmission.

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PubMed1992

Sporozoite transmission by Anopheles freeborni and Anopheles gambiae experimentally infected with Plasmodium falciparum.

A micro-membrane feeding technique was used to evaluate sporozoite transmission for Anopheles freeborni and An. gambiae experimentally infected with Plasmodium falciparum. From cohorts of infected mosquitoes with equivalent sporozoite loads, 75.9% of 29 An. freeborni transmitted a geometric mean (GM) of 4.9 sporozoites and 80% of 30 An. gambiae transmitted a GM of 11.3 sporozoites. Ingested sporozoites, in the blood meal immediately after feeding, were detected in 86.2% of 29 An. freeborni (GM = 9.0) and in 70% of 30 An. gambiae (GM = 44.1). Overall, sporozoites were transmitted and/or ingested by 90% of both species. Most infective mosquitoes transmitted < 1% of the total sporozoites in the salivary glands, and only up to 30% of the variation in transmission, ingestion, or total sporozoite output was related to sporozoite loads. The demonstration that An. gambiae transmitted more than twice as many sporozoites as An. freeborni is the first indication that vector species of anopheline mosquitoes differ in their innate potential for sporozoite transmission.

Animals↗
PubMed1991

[Observation on the contraction process of ovarioles of Anopheles sinensis and Anopheles anthropophagus after oviposition].

In order to know the process of ovariole contraction after oviposition in Anopheles sinensis and An. Anthropophagus, and to determine the relationship between the ovariole contraction and the physiological age, the observation was conducted in 1988. The laboratory-reared female mosquitoes after 3-5 days of eclosion were fed with mouse blood and were kept in separate finger tubes for oviposition. After oviposition, the mosquitoes were dissected at different time. 30 ovarioles for each mosquito were examined and recorded by Detinova's method. A total number of 75 An. sinensis with 2,262 ovarioles and 87 An. anthropophagus with 2,591 ovarioles were examined after first oviposition. The duration for ovariole contraction in the phase of A,B,C,D,E was 1, 3-6, 9-14, 15-18 and 21h respectively. A total number of 40 An. sinensis with 1,337 ovarioles and 34 An. anthropophagus with 1,099 ovarioles were examined after third oviposition. The duration for ovariole contraction in the phase of A,B,C,D,E was 1, 3-9, 12-15, 18 and 21h respectively. E phase can be found in 21-24h after oviposition. There were 29.3% and 38.0% ovarioles in C and D phase for first oviposition while 48.4% and 46.0% ovarioles in C and D phase for third oviposition. It was found that the contraction occurred first in breadth and then in length.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

Limnological and botanical characterization of larval habitats for two primary malarial vectors, Anopheles albimanus and Anopheles pseudopunctipennis, in coastal areas of Chiapas State, Mexico.

Field surveys of mosquito breeding sites on the Pacific coastal plain and foothill regions of southern Chiapas, Mexico, were carried out in the dry and wet seasons of 1988. At each site, selected environmental variables were measured or estimated, presence and percent cover of aquatic plants recorded, a water sample collected for subsequent analyses, and 10-30 dips made for mosquito larvae. Logistic regression and discriminant analyses revealed that the occurrence of Anopheles albimanus larvae in both the wet and dry seasons was positively associated with planktonic algae and negatively associated with altitude. In the dry season, An. albimanus larvae were largely restricted to the margins of permanent water bodies and were associated with the presence of floating plants, particularly Eichhornia crassipes. During the wet season An. albimanus larvae were positively associated with emergent plants, particularly seasonally flooded Cyperaceae, and phosphorus (PO4) concentrations, and were negatively associated with abundant filamentous algae, high levels of total suspended solids (TSS) and Salvinia. In the dry season, An. pseudopunctipennis larvae were positively associated with filamentous algae, altitude and the presence of Heteranthera if encountered in a riverine setting, and were negatively associated with water depth. During the wet season, flooding eliminated typical flood plain An. pseudopunctipennis habitats, and larvae were rarely encountered.

Altitude↗
PubMed1990

Studies of the susceptibility of Anopheles albimanus and Anopheles vestitipennis from Dajabon, Dominican Republic, to insecticides.

Insecticide susceptibility of Anopheles albimanus and An. vestitipennis in Dajabon Province, Dominican Republic, was investigated. Only 74.3% of An. albimanus exposed to 4% DDT for 1 h died. The mortality in this species following exposure for 1 h to 0.25% permethrin was also 74.3%. However, this species was susceptible to malathion, fenitrothion and propoxur. The mortality obtained following exposure of An. vestitipennis to 4% DDT and 0.1% propoxur, both for 1 h, was 71% and 100%, respectively. However, the number of specimens exposed to propoxur was small.

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PubMed1990

Colonization of Anopheles occidentalis and Anopheles hermsi.

The colonization of Anopheles occidentalis is described and contrasted with colonization of a related species, An. hermsi. The latter species formerly was considered to be conspecific with the former, but the 2 species differ considerably in biological characteristics.

Animals↗
PubMed1979

[Genetic distance of the malarial mosquitoes, Anopheles beklemishevi and Anopheles messeae (Diptera, Culiccidae), and their intraspecific polymorphism].

Allele frequencies at enzyme loci have been studied in Finnish populations of two species of the Anopheles maculipennis complex: A. beklemishevi and A. messeae. A. beklemishevi is spread over central and northern Finland, whereas A. messeae is found in southwestern and central Finland. The allele frequencies of these two species exhibit both similarities and differences. The results indicate that the two species do not interbreed in the nature. The allele frequencies at two loci--Hydroxybutyrate dehydrogenase (Hbdh) and Superoxide dismutase-2 (Su-2)--are almost totally different and adult individuals of the two species can be reliably diagnosed by these allelic differences. The genetic distance, D, between A. beklemishevi and A. messeae is 0.35. This value is compared with corresponding distances between other dipterans studied.

Alleles↗
PubMedDate not supplied

Hut entry and exit by Anopheles gambiae and Anopheles funestus in an unsprayed village near Kaduna in Northern Nigeria.

Hut entry and exit by An. gambiae and An. funestus were studied in an unsprayed village near Kaduna in Northern Nigeria. A high turn-over of indoor resting mosquitoes of all blood digestion stages was noted throughout the night. The behaviour of both species was similar. The entry pattern was more uniform than the exit which showed two distinct peaks around sunset and after midnight. Most of the daytime resting mosquitoes left the huts during the first hour after sunset, and therefore the mosquitoes escaping during the subsequent hours of the night were mainly those that had entered the same night and spent only a limited period inside the huts. The significance of the movement of mosquitoes is discussed in relation to entomological evaluation of the impact of residual insecticides.

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