Vector competence of mosquitoes against dengue viruses (2) Identification of two vector mosquito species by PCR(Proceedings of the 51st Annual Meeting of Southern Region)

A yearlong (Jul-15 to June-16) intensive survey was conducted to document the diversity and density of different mosquito species, breeding habitats and their status at different park in Dhaka city. A total of 11 species of mosquito were identified from the six study areas. The recorded species were An. annularis, An. culicifacies, Ae. albopictus, Ae. aegypti, Ar. subalbatus, Cx. fuscocephala, Cx. quinquefasciatus, Cx. tritaeniorhynchus, Mn. annulifera, Mn. uniformis, Tx. splendidus. Aedes albopictus (38.18%) and Ar. subalbatus (37.47%) were the predominant mosquito species followed by Cx. quinquefasciatus. Others species were found in moderate percentage. Lowest density of Cx. fuscocephala (0.6%) was recorded among the collected mosquito species from the different study area. The highest percentages of mosquito were found in Botanical garden (28.68%) followed by Ramna park, Zia uddyan, Baldha garden, Suhrawardy uddyan, and Osmani uddyan (6.67%). Fifteen different larval habitats were found in the study areas. Majority of the mosquito species was found to breed in pond. High density of Ae. albopictus mosquito were found in all study areas, which is the secondary vector of dengue viruses. Principal dengue vector mosquito, Ae. aegypti were found only in Baldha garden. Ar. subalbatus was also a dominant mosquito species in the entire site.Progressive Agriculture 28 (4): 295-301, 2017

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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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Behavioural response of mosquito vectors Aedes aegypti, Anopheles stephensi and Culex quinquefasciatus to synthetic pyrethroid and organophosphorus-based slow-release insecticidal paint

Parasites & Vectors ◽

10.1186/s13071-021-04746-x ◽

2021 ◽

Vol 14 (1) ◽

Author(s):

Sunil Dhiman ◽

Kavita Yadav ◽

B. N. Acharya ◽

Raj Kumar Ahirwar ◽

D. Sukumaran

Keyword(s):

Aedes Aegypti ◽

Culex Quinquefasciatus ◽

Anopheles Stephensi ◽

Slow Release ◽

Disease Risk ◽

Mosquito Species ◽

Escape Time ◽

Behavioural Avoidance ◽

Vector Mosquito ◽

Contact Exposure

Abstract Background The direct toxicological impact of insecticides on vector mosquitoes has been well emphasized; however, behavioural responses such as excito-repellency and physical avoidance as a result of insecticide exposure have not been much studied. We have demonstrated the excito-repellency and behavioural avoidance in certain vector mosquito species on exposure to a slow-release insecticidal paint (SRIP) formulation in addition to direct toxicity. Methods A SRIP formulation developed by the Defence Research and Development Establishment, Gwalior, contains chlorpyriphos, deltamethrin and pyriproxyfen as active insecticides. Anopheles stephensi, Culex quinquefasciatus and Aedes aegypti mosquitoes were used to study the excito-repellency response of the formulation. The experiments were performed in a specially designed dual-choice exposure and escape chamber made of transparent polymethyl methacrylate. For the experiments, the SRIP formulation was applied undiluted at a rate of 8 m2 per kg on 15 cm2 metallic surfaces. Mosquitoes were introduced into the exposure chamber, and observations of the movement of mosquitoes into the escape chamber through the exit portal were taken at 1-min intervals for up to 30 min. Results The evaluated formulation displayed strong excito-repellency against all three tested vector mosquito species. Results showed that the ET50 (escape time 50%) for Ae. aegypti, An. stephensi and Cx. quinquefasciatus was 20.9 min, 14.5 min and 17.9 min for contact exposure (CE) respectively. Altogether in CE, the escape rates were stronger in An. stephensi mosquitoes at different time intervals compared to Ae. aegypti and Cx. quinquefasciatus mosquitoes. The probit analysis revealed that the determined ET did not deviate from linearity for both non-contact exposure (NCE) and placebo exposure (PE) (χ2 ≤ 7.9; p = 1.0) for Ae. aegypti mosquitoes and for NCE (χ2 = 8.3; p = 1.0) and PE (χ2 = 1.7; p = 1.0) treatments in Cx. quinquefasciatus. Mortality (24 h) was found to be statistically higher (F = 6.4; p = 0.02) in An. stephensi for CE but did not vary for NCE (p ≥ 0.3) and PE (p = 0.6) treatments among the tested mosquito species. Survival probability response suggested that all the three tested species displayed similar survival responses for similar exposures (χ2 ≤ 2.3; p ≥ 0.1). Conclusion The study demonstrates the toxicity and strong behavioural avoidance in known vector mosquito species on exposure to an insecticide-based paint formulation. The combination of insecticides in the present formulation will broaden the overall impact spectrum for protecting users from mosquito bites. The efficacy data generated in the study provide crucial information on the effectiveness of the tested formulation and could be useful in reducing the transmission intensity and disease risk in endemic countries.

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3 Histological and biochemical studies on muscle cell death induced by Habu venom(Contributed Papers,Proceedings of the 55th Annual Meeting of Southern Region)

Medical Entomology and Zoology ◽

10.7601/mez.57.172_3 ◽

2006 ◽

Vol 57 (2) ◽

pp. 172

Author(s):

T. Kurzono ◽

A. Inoyae ◽

N. Mizoguchi ◽

K. Minakami

Keyword(s):

Cell Death ◽

Annual Meeting ◽

Muscle Cell ◽

Southern Region ◽

Biochemical Studies

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Epidemiology of West Nile virus in Africa: An underestimated threat

PLoS Neglected Tropical Diseases ◽

10.1371/journal.pntd.0010075 ◽

2022 ◽

Vol 16 (1) ◽

pp. e0010075

Author(s):

Giulia Mencattelli ◽

Marie Henriette Dior Ndione ◽

Roberto Rosà ◽

Giovanni Marini ◽

Cheikh Tidiane Diagne ◽

...

Keyword(s):

West Nile Virus ◽

Disease Burden ◽

Vector Competence ◽

Mosquito Species ◽

Global Scale ◽

Reference List ◽

African Continent ◽

West Nile ◽

Scientific Papers ◽

Epidemiological Pattern

Background West Nile virus is a mosquito-borne flavivirus which has been posing continuous challenges to public health worldwide due to the identification of new lineages and clades and its ability to invade and establish in an increasing number of countries. Its current distribution, genetic variability, ecology, and epidemiological pattern in the African continent are only partially known despite the general consensus on the urgency to obtain such information for quantifying the actual disease burden in Africa other than to predict future threats at global scale. Methodology and principal findings References were searched in PubMed and Google Scholar electronic databases on January 21, 2020, using selected keywords, without language and date restriction. Additional manual searches of reference list were carried out. Further references have been later added accordingly to experts’ opinion. We included 153 scientific papers published between 1940 and 2021. This review highlights: (i) the co-circulation of WNV-lineages 1, 2, and 8 in the African continent; (ii) the presence of diverse WNV competent vectors in Africa, mainly belonging to the Culex genus; (iii) the lack of vector competence studies for several other mosquito species found naturally infected with WNV in Africa; (iv) the need of more competence studies to be addressed on ticks; (iv) evidence of circulation of WNV among humans, animals and vectors in at least 28 Countries; (v) the lack of knowledge on the epidemiological situation of WNV for 19 Countries and (vii) the importance of carrying out specific serological surveys in order to avoid possible bias on WNV circulation in Africa. Conclusions This study provides the state of art on WNV investigation carried out in Africa, highlighting several knowledge gaps regarding i) the current WNV distribution and genetic diversity, ii) its ecology and transmission chains including the role of different arthropods and vertebrate species as competent reservoirs, and iii) the real disease burden for humans and animals. This review highlights the needs for further research and coordinated surveillance efforts on WNV in Africa.

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