Distribution of Anopheles in Vietnam, with particular attention to malaria vectors of the Anopheles minimus complex

Abstract Background The complexity of mosquito-borne diseases poses a major challenge to global health efforts to mitigate their impact on people residing in sub-tropical and tropical regions, to travellers and deployed military personnel. To supplement drug- and vaccine-based disease control programmes, other strategies are urgently needed, including the direct control of disease vectors. Modern vector control research generally focuses on identifying novel active ingredients and/or innovative methods to reduce human-mosquito interactions. These efforts include the evaluation of spatial repellents, which are compounds capable of altering mosquito feeding behaviour without direct contact with the chemical source. Methods This project examined the impact of airborne transfluthrin from impregnated textile materials on two important malaria vectors, Anopheles dirus and Anopheles minimus. Repellency was measured by movement within taxis cages within a semi-field environment at the National Institute of Hygiene and Epidemiology in Hanoi, Vietnam. Knockdown and mortality were measured in adult mosquito bioassay cages. Metered-volume air samples were collected at a sub-set of points in the mosquito exposure trial. Results Significant differences in knockdown/mortality were observed along a gradient from the exposure source with higher rates of knockdown/mortality at 2 m and 4 m when compared with the furthest distance (16 m). Knockdown/mortality was also greater at floor level and 1.5 m when compared to 3 m above the floor. Repellency was not significantly different except when comparing 2 m and 16 m taxis cages. Importantly, the two species reacted differently to transfluthrin, with An. minimus being more susceptible to knockdown and mortality. The measured concentrations of airborne transfluthrin ranged from below the limit of detection to 1.32 ng/L, however there were a limited number of evaluable samples complicating interpretation of these results. Conclusions This study, measuring repellency, knockdown and mortality in two malaria vectors in Vietnam demonstrates that both species are sensitive to airborne transfluthrin. The differences in magnitude of response between the two species requires further study before use in large-scale vector control programmes to delineate how spatial repellency would impact the development of insecticide resistance and the disruption of biting behaviour.

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BEHAVIORAL RESPONSES TO DDT AND PYRETHROIDS BETWEEN ANOPHELES MINIMUS SPECIES A AND C, MALARIA VECTORS IN THAILAND

American Journal of Tropical Medicine and Hygiene ◽

10.4269/ajtmh.2005.73.343 ◽

2005 ◽

Vol 73 (2) ◽

pp. 343-349 ◽

Cited By ~ 30

Author(s):

JINNAPA POTIKASIKORN ◽

THEERAPHAP CHAREONVIRIYAPHAP ◽

MICHAEL J. BANGS ◽

ATCHARIYA PRABARIPAI

Keyword(s):

Behavioral Responses ◽

Malaria Vectors ◽

Anopheles Minimus

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Behavioral Responses of Malaria Vectors, Anopheles minimus Complex, to Three Classes of Agrochemicals in Thailand

Journal of Medical Entomology ◽

10.1603/0022-2585(2007)44[1032:bromva]2.0.co;2 ◽

2007 ◽

Vol 44 (6) ◽

pp. 1032-1039 ◽

Cited By ~ 10

Author(s):

Jinrapa Pothikasikorn ◽

Hans Overgaard ◽

Chitapa Ketavan ◽

Surapon Visetson ◽

Michael J. Bangs ◽

...

Keyword(s):

Behavioral Responses ◽

Malaria Vectors ◽

Anopheles Minimus

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Molecular Identification of Anopheles minimus sensu lato and Anopheles dirus sensu lato (Diptera: Culicidae) from Kampong Spoe Province, Cambodia

Zootaxa ◽

10.11646/zootaxa.1028.1.3 ◽

2005 ◽

Vol 1028 (1) ◽

pp. 37 ◽

Cited By ~ 2

Author(s):

YAJUN MA ◽

SOK VANNE ◽

SHIZHU LI ◽

PIN YANG

Keyword(s):

Internal Transcribed Spacer ◽

Malaria Vectors ◽

Sequence Variant ◽

Sequence Variants ◽

Anopheles Dirus ◽

Anopheles Minimus ◽

The Third ◽

Species Complexes ◽

Second Internal Transcribed Spacer ◽

First Time

Anopheles dirus and An. minimus are primary malaria vectors in Cambodia. Both are species complexes and can be confused on the basis of adult morphology. The second internal transcribed spacer (ITS2) and the third domain (D3) in 28S of ribosomal DNA (rDNA) of An. minimus sensu lato and An. dirus s. l. were sequenced and analyzed. Three species (An. minimus A, An. sawadwongporni, and An. pampanai) and three sequence variants (MYJ-1, MYJ-2 and MYJ-3) were identified in An. minimus s. l. Two species (An. dirus A, An. pampanai) and one sequence variant (MYJ-1) were identified in An. dirus s. l. Anopheles sawadwongporni is recorded for the first time in Cambodia.

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BIOEKOLOGI VEKTOR MALARIA PADA BERBAGAI EKOSISTEM DI KABUPATEN DONGGALA, PROVINSI SULAWESI TENGAH

Vektora Jurnal Vektor dan Reservoir Penyakit ◽

10.22435/vk.v11i1.1139 ◽

2019 ◽

Vol 11 (1) ◽

pp. 1-10

Author(s):

Riyani Setiyaningsih ◽

Lasmiati Lasmiati ◽

Mujiyono Mujiyono ◽

Mega Tyas Prihatin ◽

Heru Priyanto ◽

...

Keyword(s):

Forest Ecosystems ◽

Light Trap ◽

Malaria Vectors ◽

Fish Farms ◽

Anopheles Subpictus ◽

Breeding Sites ◽

Anopheles Minimus ◽

Survey Results ◽

Central Sulawesi ◽

Anopheles Barbirostris

Central Sulawesi is one of the malaria-endemic areas in Indonesia. Anopheles nigerrimus, Anopheles barbirostris, Anopheles subpictus, Anopheles parangensis, Anopheles flavirostris and Anopheles minimus were confirmed as malaria vectors. Researchers believed that there might have a distinctly different distribution and diversity of the vectors in different ecosystems. The purpose of the current study was to investigate and analyze the distribution and diversity of suspected malaria vectors (Anopheles spp.) in various ecosystems. Adult mosquitoes were collected using some methods e.g. human man landing method, animal baited trap, mosquito caught around the cage, using sweep net and the light trap. The sporozoites of Plasmodium infecting the caught mosquitoes were identified and examined using PCR. In addition, a survey on potential breeding sites of the mosquitoes. Based on the survey results, the mosquitoes species caught in the non-forest ecosystems near the settlements and positively infected by Plasmodium were An. ludlowae, An. flavirostris, and An. vagus. Meanwhile, the malaria vectors caught in the non-forest ecosystems far from the settlements were An. maculatus and An. subpictus. The results also demonstrated that An. barbirostris was detected as a malaria vector in the coastal area near the settlement. The ponds, rivers and fish farms were potential breeding sites for the mosquitoes. The suspected malaria vectors (Anopheles spp) spread throughout ecosystems e.g. forests, non-forests and coasts. The high risk of ecosystems for malaria transmission was the non-forest ecosystems near the settlements, the non-forest far away from the settlements, and the coasts near the settlements.

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Time of Test Periods Influence the Behavioral Responses of Anopheles minimus and Anopheles dirus (Diptera: Culicidae) to DEET

Insects ◽

10.3390/insects12100867 ◽

2021 ◽

Vol 12 (10) ◽

pp. 867

Author(s):

Rungarun Tisgratog ◽

Chutipong Sukkanon ◽

Victor Arief Sugiharto ◽

Michael J. Bangs ◽

Theeraphap Chareonviriyaphap

Keyword(s):

Mosquito Species ◽

Behavioral Responses ◽

Test System ◽

Malaria Vectors ◽

Anopheles Dirus ◽

Anopheles Species ◽

Anopheles Minimus ◽

Significant Difference ◽

Escape Responses ◽

The Impact

Information on factors influencing the behavioral responses of mosquitoes to repellents is lacking and poorly understood, especially in the Anopheles species, night-biting mosquitoes. Our goal was to investigate the impact of different time periods on circadian activity and behavioral responses of two malaria vectors, Anopheles minimus and An. dirus, to 5% DEET using an excito-repellency test system. Each mosquito species was exposed to the repellent during the daytime (06.00–18.00) and nighttime (18.00–06.00), and time of observation was further divided into four 3-h intervals. Significant escape responses were observed between daytime and nighttime for An. minimus in both noncontact and contact tests. An. dirus showed statistical differences in contact irritancy escape response, whereas no significant difference was found in noncontact repellency tests. Both mosquito species showed more significantly higher escape responses when exposed to DEET during the afternoon and late in the night. This finding indicates that the time of testing may affect the behavioral responses of mosquitoes to repellents, especially in An. minimus and An. dirus. A better understanding of nocturnally active mosquito behavioral responses spanning from dusk to dawn would assist in optimizing product development, screening, and effective evaluation.

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Mapping insecticide resistance in malaria vectors: Latest updates from IR Mapper

10.1603/ice.2016.117689 ◽

2016 ◽

Author(s):

Melinda P Hadi

Keyword(s):

Insecticide Resistance ◽

Malaria Vectors

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Targeting malaria vectors through their blood meals for malaria transmission control

10.1603/ice.2016.94825 ◽

2016 ◽

Author(s):

Brian D. Foy

Keyword(s):

Malaria Transmission ◽

Malaria Vectors ◽

Transmission Control ◽

Blood Meals

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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

Parasites & Vectors ◽

10.1186/s13071-020-04563-8 ◽

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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Microbiota identified from preserved Anopheles

Malaria Journal ◽

10.1186/s12936-021-03754-7 ◽

2021 ◽

Vol 20 (1) ◽

Author(s):

Bianca E Silva ◽

Zvifadzo Matsena Zingoni ◽

Lizette L. Koekemoer ◽

Yael L. Dahan-Moss

Keyword(s):

Microbial Diversity ◽

Vector Competence ◽

Mosquito Species ◽

Anopheles Funestus ◽

Cost Effective ◽

Diversity Indices ◽

Malaria Vectors ◽

Microbial Composition ◽

Culture Independent ◽

Culture Dependent

Abstract Background Mosquito species from the Anopheles gambiae complex and the Anopheles funestus group are dominant African malaria vectors. Mosquito microbiota play vital roles in physiology and vector competence. Recent research has focused on investigating the mosquito microbiota, especially in wild populations. Wild mosquitoes are preserved and transported to a laboratory for analyses. Thus far, microbial characterization post-preservation has been investigated in only Aedes vexans and Culex pipiens. Investigating the efficacy of cost-effective preservatives has also been limited to AllProtect reagent, ethanol and nucleic acid preservation buffer. This study characterized the microbiota of African Anopheles vectors: Anopheles arabiensis (member of the An. gambiae complex) and An. funestus (member of the An. funestus group), preserved on silica desiccant and RNAlater® solution. Methods Microbial composition and diversity were characterized using culture-dependent (midgut dissections, culturomics, MALDI-TOF MS) and culture-independent techniques (abdominal dissections, DNA extraction, next-generation sequencing) from laboratory (colonized) and field-collected mosquitoes. Colonized mosquitoes were either fresh (non-preserved) or preserved for 4 and 12 weeks on silica or in RNAlater®. Microbiota were also characterized from field-collected An. arabiensis preserved on silica for 8, 12 and 16 weeks. Results Elizabethkingia anophelis and Serratia oryzae were common between both vector species, while Enterobacter cloacae and Staphylococcus epidermidis were specific to females and males, respectively. Microbial diversity was not influenced by sex, condition (fresh or preserved), preservative, or preservation time-period; however, the type of bacterial identification technique affected all microbial diversity indices. Conclusions This study broadly characterized the microbiota of An. arabiensis and An. funestus. Silica- and RNAlater®-preservation were appropriate when paired with culture-dependent and culture-independent techniques, respectively. These results broaden the selection of cost-effective methods available for handling vector samples for downstream microbial analyses.

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