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.

Human biting rhythm of Anopheles gambiae s.l. and sleeping behaviour of pregnant women in a lagoon area in Southern Benin

2021 ◽  
Author(s):  
Armel DJENONTIN ◽  
Aziz BOURAÏMA ◽  
Christophe SOARES ◽  
Seun EGBINOLA ◽  
Gilles COTTRELL
Keyword(s):  
Plasmodium Falciparum ◽  
Pregnant Women ◽  
Anopheles Gambiae ◽  
Early Morning ◽  
Allelic Frequency ◽  
Malaria Vectors ◽  
Mosquito Nets ◽  
Anopheles Gambiae S.L ◽  
Almost All ◽  
Southern Benin

Abstract ObjectiveIn 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.ResultsOverall, 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 with the exception of two, which were Anopheles melas. 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 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.

scholarly journals Plasmodium falciparum (Haemosporodia: Plasmodiidae) and O’nyong-nyong Virus Development in a Transgenic Anopheles gambiae (Diptera: Culicidae) Strain

2019 ◽  
Vol 56 (4) ◽  
pp. 936-941 ◽  
Author(s):  
John D Mumford ◽  
Carole A Long ◽  
Scott C Weaver ◽  
Katzutoyo Miura ◽  
Eryu Wang ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Anopheles Gambiae ◽  
Genetic Background ◽  
Homing Endonuclease ◽  
Virus Titer ◽  
Consistent Difference ◽  
Human Pathogens ◽  
Infectious Dose ◽  
Anopheles Gambiae Giles ◽  
Transgenic Mosquitoes

Abstract Transgenic Anopheles gambiae Giles (Diptera: Culicidae) mosquitoes have been developed that confer sexual sterility on males that carry a transgene encoding a protein which cuts ribosomal DNA. A relevant risk concern with transgenic mosquitoes is that their capacity to transmit known pathogens could be greater than the unmodified form. In this study, the ability to develop two human pathogens in these transgenic mosquitoes carrying a homing endonuclease which is expressed in the testes was compared with its nontransgenic siblings. Infections were performed with Plasmodium falciparum (Welch) and o’nyong-nyong virus (ONNV) and the results between the transgenic and nontransgenic sibling females were compared. There was no difference observed with ONNV isolate SG650 in intrathoracic infections or the 50% oral infectious dose measured at 14 d postinfection or in mean body titers. Some significant differences were observed for leg titers at the medium and highest doses for those individuals in which virus titer could be detected. No consistent difference was observed between the transgenic and nontransgenic comparator females in their ability to develop P. falciparum NF54 strain parasites. This particular transgene caused no significant effect in the ability of mosquitoes to become infected by these two pathogens in this genetic background. These results are discussed in the context of risk to human health if these transgenic individuals were present in the environment.

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.

An analysis of the numbers of Anopheles gambiae Giles and A. Funestus Giles (Diptera, Culicidae) in huts in Northern Nigeria

1964 ◽  
Vol 55 (1) ◽  
pp. 29-34 ◽  
Author(s):  
M. W. Service
Keyword(s):  
Anopheles Gambiae ◽  
Breeding Site ◽  
Early Morning ◽  
Simple Relationship ◽  
Northern Nigeria ◽  
Positive Correlation ◽  
Factors Influencing ◽  
Significant Difference ◽  
Anopheles Gambiae Giles

Pyrethrum spray-sheet collections in a small village in Northern Nigeria showed that there was no significant difference in the numbers of Anopheles gambiae Giles and A. funestus Giles caught at different times in the early morning. In this village, huts at the edge nearest to the only breeding site attracted considerably more adults than those further away from the edge, and some huts were consistently more attractive to mosquitos than others. There was a positive correlation between the numbers of A. gambiae and A. funestus in the huts. Although significant differences were found between numbers of mosquitos caught in the huts occupied by different numbers of people, no simple relationship could be discovered between the combined densities of the two species and the number of hut occupants. It is concluded that there is need for further investigations into the factors influencing densities of the Anophelines in village huts.

scholarly journals Mosquitoes fauna diversity, Plasmodium falciparum infection and insecticide resistance status in malaria vectors in a lagoon area in Southern Benin, West Africa

2017 ◽  
Vol 5 (of) ◽  
Author(s):  
A. Djènontin ◽  
B. Zogo ◽  
J. Ahlonsou ◽  
A. Bouraima ◽  
M. Ibikounle ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Insecticide Resistance ◽  
Malaria Vector ◽  
Abundant Species ◽  
Allelic Frequency ◽  
Falciparum Infection ◽  
Malaria Vectors ◽  
Anopheles Coluzzii ◽  
Resistance Level ◽  
Plasmodium Falciparum Infection

Lagoon areas maintain ideal water conditions for mosquito breeding habitats and are thus environments with high risk of malaria transmission. In Benin, several administrative units, among which the Sô-Ava District, are located in lagoon areas. We conducted entomological surveys in this lagoon district from July 2014 to June 2015, in order to update existing information on biodiversity of mosquitoes, Plasmodium falciparum infection, and insecticide resistance status in malaria vectors. Our survey found that Culex quinquefasciatus and Mansonia africana were the most abundant species, and that Anopheles coluzzii represented the main malaria vector in this area, followed by Anopheles melas. Only Anopheles coluzzii was positive to Plasmudium falcimarum circum sporozoitic protein (4.2 %). An. gambiae s.l. were susceptible to chlorpyrifos-methyl and bendiocarb but resistant to all pyrethroids tested and to pyrimiphos-methyl. The average of kdr allelic frequency from July 2014 to June 2015 was 77.4% and that of ace1 gene was less than 1%. We conclude that Anopheles coluzzii is the main malaria vector in the lagoon area we studied, somewhat contrary to our expectations. However, this malaria vector was resistant to insecticides used for bed net impregnation, even if the resistance level was lower than observed in other parts of Benin.

Efficacy of mosquito nets treated with insecticide mixtures or mosaics against insecticide resistant Anopheles gambiae and Culex quinquefasciatus (Diptera: Culicidae) in Côte d'Ivoire

2003 ◽  
Vol 93 (6) ◽  
pp. 491-498 ◽  
Author(s):  
J.-M. Hougard ◽  
V. Corbel ◽  
R. N'Guessan ◽  
F. Darriet ◽  
F. Chandre ◽  
...  
Keyword(s):  
Anopheles Gambiae ◽  
Culex Quinquefasciatus ◽  
Resistance Management ◽  
Blood Feeding ◽  
Malaria Vectors ◽  
Mosquito Net ◽  
Pyrethroid Insecticides ◽  
Mosquito Nets ◽  
Experimental Huts ◽  
Insecticide Mixtures

AbstractOnly pyrethroid insecticides have so far been recommended for the treatment of mosquito nets for malaria control. Increasing resistance of malaria vectors to pyrethroids threatens to reduce the potency of this important method of vector control. Among the strategies proposed for resistance management is to use a pyrethroid and a non-pyrethroid insecticide in combination on the same mosquito net, either separately or as a mixture. Mixtures are particularly promising if there is potentiation between the two insecticides as this would make it possible to lower the dosage of each, as has been demonstrated under laboratory conditions for a mixture of bifenthrin (pyrethroid) and carbosulfan (carbamate). The effect of these types of treatment were compared in experimental huts on wild populations of Anopheles gambiae Giles and the nuisance mosquito Culex quinquefasciatus Say, both of which are multi-resistant. Four treatments were evaluated in experimental huts over six months: the recommended dosage of 50 mg m−2 bifenthrin, 300 mg m−2 carbosulfan, a mosaic of 300 mg m−2 carbosulfan on the ceiling and 50 mg m−2 bifenthrin on the sides, and a mixture of 6.25 mg m−2 carbosulfan and 25 mg m−2 bifenthrin. The mixture and mosaic treatments did not differ significantly in effectiveness from carbosulfan and bifenthrin alone against anophelines in terms of deterrency, induced exophily, blood feeding inhibition and overall mortality, but were more effective than in earlier tests with deltamethrin. These results are considered encouraging, as the combination of different classes of insecticides might be a potential tool for resistance management. The mixture might have an advantage in terms of lower cost and toxicity.

scholarly journals Insecticide resistance status of malaria vectors Anopheles gambiae (s.l.) of southwest Burkina Faso and residual efficacy of indoor residual spraying with microencapsulated pirimiphos-methyl insecticide

2021 ◽  
Vol 14 (1) ◽  
Author(s):  
Dieudonné Diloma Soma ◽  
Barnabas Zogo ◽  
Domonbabele François de Sales Hien ◽  
Aristide Sawdetuo Hien ◽  
Didier Alexandre Kaboré ◽  
...  
Keyword(s):  
Insecticide Resistance ◽  
Burkina Faso ◽  
Anopheles Gambiae ◽  
Local Population ◽  
Residual Activity ◽  
Indoor Residual Spraying ◽  
Susceptible Strain ◽  
Malaria Vectors ◽  
Pirimiphos Methyl ◽  
Residual Efficacy

Abstract Background The rapid spread of insecticide resistance in malaria vectors and the rebound in malaria cases observed recently in some endemic areas underscore the urgent need to evaluate and deploy new effective control interventions. A randomized control trial (RCT) was conducted with the aim to investigate the benefit of deploying complementary strategies, including indoor residual spraying (IRS) with pirimiphos-methyl in addition to long-lasting insecticidal nets (LLINs) in Diébougou, southwest Burkina Faso. Methods We measured the susceptibility of the Anopheles gambiae (s.l.) population from Diébougou to conventional insecticides. We further monitored the efficacy and residual activity of pirimiphos-methyl on both cement and mud walls using a laboratory susceptible strain (Kisumu) and the local An. gambiae (s.l.) population. Results An. gambiae (s.l.) from Diébougou was resistant to DDT, pyrethroids (deltamethrin, permethrin and alphacypermethrin) and bendiocarb but showed susceptibility to organophosphates (pirimiphos-methyl and chlorpyrimiphos-methyl). A mixed-effect generalized linear model predicted that pirimiphos-methyl applied on cement or mud walls was effective for 210 days against the laboratory susceptible strain and 247 days against the local population. The residual efficacy of pirimiphos-methyl against the local population on walls made of mud was similar to that of cement (OR = 0.792, [0.55–1.12], Tukey’s test p-value = 0.19). Conclusions If data on malaria transmission and malaria cases (as measured trough the RCT) are consistent with data on residual activity of pirimiphos-methyl regardless of the type of wall, one round of IRS with pirimiphos-methyl would have the potential to control malaria in a context of multi-resistant An. gambiae (s.l.) for at least 7 months.

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