Comparative studies on sibling species of the Anopheles gambiae Giles complex (Dipt., Culicidae). III. The distribution, ecology, behaviour and vectorial importance of species D in Bwamba County, Uganda, with an analysis of biological, ecological, morphological and cytogenetical relationships of Ugandan species D

1973 ◽  
Vol 63 (1) ◽  
pp. 65-97 ◽  
Author(s):  
G. B. White
Keyword(s):  
Anopheles Gambiae ◽  
Sibling Species ◽  
Comparative Studies ◽  
Hot Springs ◽  
Limited Range ◽  
Brackish Marsh ◽  
Complex Species ◽  
Human Malaria ◽  
Chromosomal Inversions ◽  
Anopheles Gambiae Giles

AbstractStudies on mosquitoes of the Anopheles gambiae Giles complex at Bwamba, Uganda, showed that the newly recognized sibling species D may be restricted to breeding areas where waters contain unusual solutes, the effluent from hot springs at Buranga being particularly favourable. Two other members of the complex, species A and B, were also detected in the neighbourhood apparently breeding only in more normal situations. Species D specimens were usually identified cytotaxonomically, from the presence of XR potytene chromosomes of the type also occurring in species C and A. melas (Theo.) (neither of which is known from the area). Most species D females have distinctively pale palps, a valuable although limited distinguishing feature. Features of setation on larvae and pupae were discerned which might serve usefully as meristic chaetotaxonomic factors, at least locally, if tested further. Although it is unquestionable that a large proportion of species D females forage in the Semliki forest, feeding on primates, bovids, suids or unsuspected hosts, it was demonstrated that many species D females are markedly anthropophilic and display strong endophilic and endophagic tendencies, to the extent that they may be primary vectors of human malaria and filariasis over a limited range. Species D males were rare indoors and remained mainly within the forest, where great numbers rest low on vegetation in company with unfed females, near to breeding areas of brackish marsh. Two polymorphic chromosomal inversions in species D apparently embody the genetical causes of its differentiation. Cytogenetical evidence indicates that species D is phylogenetically nearly intermediate between A. melas and species C of the A. gambiae complex.

Comparative studies on sibling species of the Anopheles gambiae Giles complex (Dipt., Culicidae): bionomics and vectorial activity of species A and species B at Segera, Tanzania

1972 ◽  
Vol 62 (2) ◽  
pp. 295-317 ◽  
Author(s):  
G. B. White ◽  
S. A. Magayuka ◽  
P. F. L. Boreham
Keyword(s):  
Survival Rate ◽  
Anopheles Gambiae ◽  
Sibling Species ◽  
Malaria Vectors ◽  
Daily Survival Rate ◽  
Filarial Infection ◽  
Blood Indices ◽  
Biting Rate ◽  
Short Rains ◽  
Anopheles Gambiae Giles

Collections of Anopheles gambiae Giles complex, A. funestus Giles group and other mosquitoes were made by spray-catch from twelve catching stations indoors and by hand-catch from pit shelters at two catching stations at Segera, Tanzania, between January 1970 and June 1971. Females of A. gambiae were identified cytotaxonomically as sibling species A or B of the complex. In houses during 1970, A. gambiae species B was more numerous at first than A, but A became predominant during the long rains of March-May. In the cool dry weather of June-November both A and B densities declined and the A:B ratio surpassed 50:1. The short rains in December produced a population explosion of species B and less multiplication of species A, the B:A ratio reaching >11:1. In 1971, hot dry weather during January-March caused declines of species A and B with a maximum B: A ratio of 13:1. Long rains, coming in late March, provoked a resurgence of A and a concurrent decline of B, so that the A:B ratio again reached 20:1 in June. Similar cycles of species A and B were observed outdoors, although the relative numbers outdoors/indoors averaged 2·3 times more for species B than for species A. In A. funestus, A. gambiae species A and A. gambiae species B Human Blood Indices were 97·5%, 91·2% and 60·9% indoors and 24%, 2% and 7% outdoors, respectively. Respective malaria sporozoite rates were 1·62%, 4·23% and 0·32% and minimum rates of stage-Ill filarial infection were 0·33%, 0·44% and 0·57%. Sporozoite-positive and sporozoite-negative mosquitoes exhibited similar HBF's in species A and discrepant HBI's in species B. The HBI's were higher in filariapositive A and B females than in filaria-negative females. Gregarines occurred in 1·36% of species A and 0·38% of species B. Trematode cysts were seen in two specimens of species A.Of A and B females 28% and 4%, respectively, had four-banded palps. It is shown mathematically that the discrepant malaria sporozoite rates in species A and B may be explained by extrapolating from the man-biting rate and probable daily survival rate for each species. This implies that no unrecognised factors play a major role in causing the contrasting efficiency of these two sibling species as malaria vectors.

Mortalities of the larvae of the Anopheles gambiae Giles complex and detection of predators by the precipitin test

1973 ◽  
Vol 62 (3) ◽  
pp. 359-369 ◽  
Author(s):  
M. W. Service
Keyword(s):  
Anopheles Gambiae ◽  
High Mortality ◽  
Survival Rates ◽  
Age Distribution ◽  
Fourth Instar ◽  
Immature Stages ◽  
Complex Species ◽  
Precipitin Test ◽  
Anopheles Gambiae Giles ◽  
Time Specific

Larval populations of the Anopheles gambiae Giles complex (species A and B) were sampled in Kenya, and from the frequencies of the age distribution of the immature stages time-specific life-tables were constructed. Daily survival rates and instar mortalities showed that there was high mortality amongst fourth-instar larvae, due at least in part to infections of larval nematodes, Coelomomyces and epibionts. Antiserum to the A. gambiae complex was prepared in rabbits so that the precipitin test could be employed to detect the presence of A. gambiae in gut smears taken from possible predators. By this serological technique various spiders, Diptera, Coleoptera and amphibia were identified as predators. These may be very important in regulating populations of A. gambiae even in small collections of water.

Studies on the sibling species Anopheles gambiae Giles and Anopheles arabiensis Patton (Diptera: Culicidae) in the Kisumu area, Kenya.

1979 ◽  
Vol 69 (1) ◽  
pp. 43-53 ◽  
Author(s):  
R. B. Highton ◽  
Joan H. Bryan ◽  
P. F. L. Boreham ◽  
J. A Chandler
Keyword(s):  
Anopheles Gambiae ◽  
Sibling Species ◽  
Malaria Infection ◽  
Anopheles Arabiensis ◽  
Dominant Species ◽  
Feeding Habits ◽  
Seasonal Abundance ◽  
Infection Rates ◽  
Sporozoite Rate ◽  
Anopheles Gambiae Giles

AbstractA study was undertaken of the seasonal abundance, feeding habits, resting habits and malaria infection rates of the sibling species Anopheles gambiae Giles and A. arabiensis Patton on the Kano Plain, Kenya, and the surrounding foothills. A. arabiensis was the dominant species on the plains and A. gambiae in the foothills. A. gambiae was highly anthropophilic with 92% feeding on man, whereas 59% of A. arabiensis fed on cattle. In both species, the choice of host was affected by the availability of cattle. A. arabiensis rested out of doors more commonly than A. gambiae. The sporozoite rate in A. gambiae was 5·33%, 15·98 times higher than the rate of 0·33% found in A. arabiensis.

scholarly journals Entomocidal properties of Monodora myristica (Dunal, 1831) and Conyza sumatrensis (Retzius, 1742-1821) extracts: Studies on two dipterous insect pests Anopheles gambiae (Giles, 1902) and Culex quinquefasciatus (Say, 1823)

2018 ◽  
Vol 5 (10) ◽  
pp. 347-358
Author(s):  
Kayode David Ileke
Keyword(s):  
Anopheles Gambiae ◽  
Lymphatic Filariasis ◽  
Plant Extracts ◽  
Culex Quinquefasciatus ◽  
Insect Pests ◽  
Mosquito Species ◽  
Human Malaria ◽  
Anopheles Gambiae Giles ◽  
Monodora Myristica ◽  
Lc50 And Lc90

Anopheles gambiae (Giles, 1902) and Culex quinquefasciatus (Say, 1832) mosquitoes are the main vectors of human malaria and lymphatic filariasis, respectively. This study aims to analyze the larvicidal, pupicidal and adulticidal properties of Monodora myristica (Dunal, 1831) and Conyza sumatrensis (Retzius, 1742-1821) extracts against An. gambiae and Cx. quinquefasciatus. The experiment was conducted in the laboratory at ambient temperature of 28 oC +/- 2 oC and 75% +/- 5% relative humidity. The results showed that M. myristica and C. sumatrensis extracts significantly affect all stages of An. gambiae and Cx. quinquefasciatus tested. The mosquitocidal toxicity of the two plant extracts is dosage dependent. Anti-larval activity of M. myristica at rate 500 mg/L and 1,000 mg/L caused 100% mortality of An. gambiae larvae while it evoked 80% and 100% mortality of Cx. quinquefasciatus larvae. The same trend of results were also obtained on the anti-pupal and adulticidal toxicity of M. myristica and C. sumatrensis extracts. As larvicides, pupicides and adulticides, the LC50s and LC90s, after 24 h varied across plant extracts and mosquito species. C. sumatrensis attained LC50 and LC90 at higher concentration than M. myristica. On An. gambiae larvae, the LC50s after 24 h, varied from 86.95 mg/L (M. myristica) to 131.73 mg/L (C. sumatrensis). Similarly, the LC90s after 24 h on An. gambiae larvae, varied from 278.39 mg/L (M. myristica) to 131.73 mg/L (C. sumatrensis). For Cx. quinquefasciatus larvae, the LC50s after 24 h, varied from 391.41 mg/L (M. myristica) to 898.20 mg/L (C. sumatrensis). The seed extract of M. myristica exerted the best pupicidal activity among the two tested extracts with LC50 and LC90 values of 140.61 mg/L and 520.35 mg/L on An. gambiae, respectively, followed by leaf of C. sumatrensis with LC50 and LC90 values of 157.59 mg/L and 781.86 mg/L on An. gambiae, respectively. More concentrations were require to achieve 50% and 90% death of Cx. quinquefasciatus pupae. On adulticidal activity, seed of M. myristica exerted LC50 and LC90 values of 122.79 mg/L and 502.99 mg/L on An. gambiae, respectively, followed by leaf of C. sumatrensis with LC50 and LC90 values of 215.05 mg/L and 981.25 mg/L on An. gambiae, respectively. More concentrations were require to achieve 50% and 90% death of Cx. quinquefasciatus adults. The two tested plants can be integrated into pest management programmes to combat human malaria and lymphatic filariasis vectors breeding site in Nigeria. I recommend formulation of M. myristica seeds which have the lowest LC50 and LC90 after 24 h of exposure for field evaluation.

scholarly journals Laboratory and microcosm experiments reveal contrasted adaptive responses to ammonia and water mineralisation in aquatic stages of the sibling species Anopheles gambiae (sensu stricto) and Anopheles coluzzii

2021 ◽  
Vol 14 (1) ◽  
Author(s):  
Nwamaka Oluchukwu Akpodiete ◽  
Frédéric Tripet
Keyword(s):  
West Africa ◽  
Anopheles Gambiae ◽  
Emerging Adults ◽  
Sibling Species ◽  
Adult Emergence ◽  
Ecological Speciation ◽  
Sensu Stricto ◽  
Rice Fields ◽  
Anopheles Coluzzii ◽  
Phenotypic Quality

Abstract Background The sibling species of the malaria mosquito, Anopheles gambiae (sensu stricto) and Anopheles coluzzii co-exist in many parts of West Africa and are thought to have recently diverged through a process of ecological speciation with gene flow. Divergent larval ecological adaptations, resulting in Genotype-by-Environment (G × E) interactions, have been proposed as important drivers of speciation in these species. In West Africa, An. coluzzii tends to be associated with permanent man-made larval habitats such as irrigated rice fields, which are typically more eutrophic and mineral and ammonia-rich than the temporary rain pools exploited by An. gambiae (s.s.) Methods To highlight G × E interactions at the larval stage and their possible role in ecological speciation of these species, we first investigated the effect of exposure to ammonium hydroxide and water mineralisation on larval developmental success. Mosquito larvae were exposed to two water sources and increasing ammonia concentrations in small containers until adult emergence. In a second experiment, larval developmental success was compared across two contrasted microcosms to highlight G × E interactions under conditions such as those found in the natural environment. Results The first experiment revealed significant G × E interactions in developmental success and phenotypic quality for both species in response to increasing ammonia concentrations and water mineralisation. The An. coluzzii strain outperformed the An. gambiae (s.s.) strain under limited conditions that were closer to more eutrophic habitats. The second experiment revealed divergent crisscrossing reaction norms in the developmental success of the sibling species in the two contrasted larval environments. As expected, An. coluzzii had higher emergence rates in the rice paddy environment with emerging adults of superior phenotypic quality compared to An. gambiae (s.s.), and vice versa, in the rain puddle environment. Conclusions Evidence for such G × E interactions lends support to the hypothesis that divergent larval adaptations to the environmental conditions found in man-made habitats such as rice fields in An. coluzzii may have been an important driver of its ecological speciation.

scholarly journals The regulatory genome of the malaria vector Anopheles gambiae: integrating chromatin accessibility and gene expression

2021 ◽  
Vol 3 (1) ◽  
Author(s):  
José L Ruiz ◽  
Lisa C Ranford-Cartwright ◽  
Elena Gómez-Díaz
Keyword(s):  
Gene Expression ◽  
Transcriptional Regulation ◽  
Anopheles Gambiae ◽  
Mosquito Control ◽  
Regulatory Elements ◽  
Chromatin Accessibility ◽  
Malaria Vectors ◽  
Specific Gene ◽  
Mosquito Vector ◽  
Human Malaria

Abstract Anopheles gambiae mosquitoes are primary human malaria vectors, but we know very little about their mechanisms of transcriptional regulation. We profiled chromatin accessibility by the assay for transposase-accessible chromatin by sequencing (ATAC-seq) in laboratory-reared A. gambiae mosquitoes experimentally infected with the human malaria parasite Plasmodium falciparum. By integrating ATAC-seq, RNA-seq and ChIP-seq data, we showed a positive correlation between accessibility at promoters and introns, gene expression and active histone marks. By comparing expression and chromatin structure patterns in different tissues, we were able to infer cis-regulatory elements controlling tissue-specific gene expression and to predict the in vivo binding sites of relevant transcription factors. The ATAC-seq assay also allowed the precise mapping of active regulatory regions, including novel transcription start sites and enhancers that were annotated to mosquito immune-related genes. Not only is this study important for advancing our understanding of mechanisms of transcriptional regulation in the mosquito vector of human malaria, but the information we produced also has great potential for developing new mosquito-control and anti-malaria strategies.

scholarly journals Human biting rhythm of Anopheles gambiae Giles, 1902 (Diptera: Culicidae) and sleeping behaviour of pregnant women in a lagoon area in Southern Benin

2021 ◽  
Vol 14 (1) ◽  
Author(s):  
Armel Djènontin ◽  
Aziz Bouraima ◽  
Christophe Soares ◽  
Seun Egbinola ◽  
Gilles Cottrell
Keyword(s):  
Plasmodium Falciparum ◽  
Pregnant Women ◽  
Anopheles Gambiae ◽  
Early Morning ◽  
Allelic Frequency ◽  
Malaria Vectors ◽  
Mosquito Nets ◽  
Anopheles Gambiae Giles ◽  
Almost All ◽  
Southern Benin

Abstract Objective In the framework of EVALMOUS study aiming to assess the use and effectiveness of mosquito nets by pregnant women and other members of their household in a lagoon area in southern Benin, the behaviour of pregnant women relative to the time they go to bed using the net were recorded. Malaria vectors biting rhythm, Plasmodium falciparum infection and insecticide resistance genes in malaria vectors were also determined. Results Overall, 3848 females of Anopheles gambiae s. l were collected and 280 pregnant women responded to the survey. Almost all Anopheles gambiae s. l. tested were Anopheles coluzzi Coetzee and Wilkerson 2013 (Diptera: Culicidae). The CSP index in malaria vector was 1.85% and the allelic frequency of kdr gene was 74.4%. Around 90% of bites and Plasmodium falciparum Welch, 1897 (Haemosporida: Plasmodiidae) transmission occurred between 10 p.m. and 6 a.m., which coincides with the period when more than 80% of pregnant women were under bednet. Despite a slight early evening and early morning biting activity of malaria vectors in the study area, the good use of nets might remain a useful protection tool against mosquito biting and malaria transmission.

Studies of House Leaving and Outside Resting of Anopheles gambiae Giles and Anopheles funestus Giles in East Africa. I.—The Outside Resting Population

1954 ◽  
Vol 45 (2) ◽  
pp. 361-373 ◽  
Author(s):  
M. T. Gillies
Keyword(s):  
Anopheles Gambiae ◽  
Anopheles Funestus ◽  
Drastic Reduction ◽  
Natural Conditions ◽  
Resting Sites ◽  
Lowland Area ◽  
Set Up ◽  
Anopheles Gambiae Giles ◽  
Gravid Females ◽  
Periodic Examination

The behaviour of Anopheles gambiae Giles and A. funestus Giles was studied under natural conditions in a lowland area of Tanganyika.Studies on the outside resting population were carried out by direct searching for natural resting sites, and by the use of artificial box shelters partly buried in the ground in shaded localities. Catches in these give a valid sample when set up at some distance from houses.Fed and gravid females comprised 67 per cent. of the outside resting gambiae population, the latter group being between 12 and 4·5 times as numerous as the former. Rather less than half the funestus females caught were unfed, the remainder of the population being mainly composed of gravid females.Precipitin tests on the small numbers of fed females caught outside were nearly all positive for man.The identification of gravid funestus females was confirmed by periodic examination of the eggs.Entry of females into outside shelters did not occur solely in the period around sunrise. An appreciable number of funestus females did not enter before 07.00 hours and this was particularly so in shaded shelters.The building of a hut in the vicinity of a box shelter caused a drastic reduction in the numbers of mosquitos resting in the latter.Outside biting activity in these two species is of negligible importance as a source of females resting outside.

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