Refractoriness of Indian Aedes aegypti to Oral Infection with Yellow Fever Virus 17D Strain

Yellow fever virus (YFV) is the causative agent of yellow fever. It is one of the most important hemorrhagic arboviral infection of global public health significance. It is categorised under category ‘C’ of potential bioterrorism agent. Effect of geographical variation on vector competence in Ae. aegypti has been well documented for several viruses including YFV. In the present study, the vector competence of Ae. aegypti mosquitoes collected from Gwalior, India for YFV 17D vaccine strain was evaluated to understand the risk of its transmission. Further the risk associated with transmission of YFV 17D vaccine strain from viremic vaccinees to mosquitoes and subsequently to naive individuals was assessed. Ae. aegypti were orally infected with high titer of YFV 17D strain and the infection status was investigated at 7 and 14 day post infection (dpi) using a highly sensitive quantitative RT-PCR assay. None of the Ae. aegypti mosquito orally infected with YFV 17D strain was found to be positive for YFV. The infection rate was found to be zero per cent at both 7 dpi and 14 dpi. These results demonstrated the inability of the YFV 17D strain to cause infection or replication in the midgut of Ae. aegypti. Due to the highly attenuated replication of this strain in Ae. aegypti midgut, there is a minimal risk of its transmission. Further, it is unlikely for a mosquito that feeds on a viremic vaccine to get infected with this vaccine strain. The risk of transmission of YFV 17D strain by Indian Ae. aegypti mosquitoes is negligible. Further vector competence study using epidemic strain of YFV will aid in risk assessment analysis of YFV in India

Quantitative evaluation of essential oils for the identification of chemical constituents by gas chromatography/mass spectrometry

Essential oils are greatly strenuous aromatic materials having various constituents. They are used in the preparation of various precious substances like making perfumes, medicines, cleaning agent, and aromatic treatment etc. The purpose of the present investigation was to identify the major and minor chemical constituent in eighteen essential oils viz., amyris, basil, black pepper, camphor, catnip, chamomile, cinnamon, citronella, dill, frankincense, galbanum, jasmine, juniper, lavender, peppermint, rosemary, tagetes and thyme with the help of gas chromatography /mass spectrometry (GC/MS). In eighteen essential oils the identified compounds studied by GC-MS contain various types of high and low molecular weights of chemical ingredients. Therefore, GC/MS efficiently and speedily screened all the volatile elements present in the essential oils for the quantitative use of these identified chemical constituents for various reasons

Distribution of Anopheles culicifacies and Detection of its Sibling Species E from Madhya Pradesh: Central India.

Background: Anopheles culicifacies is an important vector of malaria in Southeast Asia, contributing to almost 70%of malaria cases in India. It exists as a complex of five morphologically indistinguishable species A, B, C, D and E with varied geographical distribution patterns. In India, 8% of the total population of Madhya Pradesh (Central India) contributes about 30% of total malaria cases, 60% of total falciparum cases and 50% of malaria deaths. An. culicifacies is the major malaria vector in this state. Vector control mainly relies on the proper identification and distribution of vector species exists in a particular area. The present study was carried out to identify the distribution of An. culicifacies sibling species in certain endemic district of Central India, Madhya Pradesh. Methods: The An. culicifacies mosquitoes collected from the study districts were identified morphologically. The genomic DNA was isolated from the mosquitoes and subjected to Allele specific PCR targeting D3 domain of 28S ribosomal DNA. Results: The mean prevalence of An. culicifacies during the study period was in the range of 8–120 per man per hour (PMH). From the study areas species B was identified from Jabalpur, Chindwara and Hoshangabad, Species C from Hoshangabad only, Species D from Narsinghpur and Khandwa and sibling species E from Mandla, Chindwara and Hoshangabad respectively. Conclusion: This  is  the  first  report  to  detect  species  E  from  Madhya  Pradesh  region  which  necessitate  for reconsideration of species distribution of each An. culicifacies sibling species that would enable to develop required vector control strategies

Differential Larval Toxicity and Oviposition Altering Activity of Some Indigenous Plant Extracts against Dengue and Chikungunya Vector Aedes albopictus.

Background: Mosquitoes are well known as vectors of several disease causing pathogens. The extensive use of synthetic insecticides in the mosquito control strategies resulted to the development of pesticide resistance and fos- tered environmental deterioration. Hence in recent years plants become alternative source of mosquito control agents. The present study assessed the larvicidal and oviposition altering activity of six different plants species- Alstonia scholaris, Callistemon viminalis, Hyptis suaveolens, Malvastrum coromandelianum, Prosopis juliflora, Vernonia cinerea against Aedes albopictus mosquito in laboratory. Methods: Leaf extracts of all the six plants species in five different solvents of various polarities were used in the range of 20–400ppm for larval bioassay and 50,100 and 200ppm for cage bioassay (for the study of oviposition be- havior) against Ae. albopictus. The larval mortality data were recorded after 24 h and subjected to Probit analysis to determine the lethal concentrations (LC50), while OAI (Oviposition activity index) was calculated for oviposition altering activity of the plant extracts. Results: Vernonia cinerea extract in acetone and C. viminalis extract in isopropanol were highly effective against Aedes albopictus larvae with LC50 value 64.57, 71.34ppm respectively. Acetone extract of P.  juliflora found to be strong oviposition-deterrent which inhibited >2 fold egg laying (OAI-0.466) at 100ppm. Conclusion: Vernonia cinerea and C. viminallis leaf extracts have the potential to be used as larvicide and P.juliflora as an oviposition-deterrent for the control of Ae. albopictus mosquito

Behavioral Response of Aedes aegypti Mosquito towards Essential Oils Using Olfactometer

Background: Aedes aegypti mosquito is responsible for transmitting human diseases like dengue and chikungunya. Personal or space protection with insect repellents is a practical approach to reducing human mosquito contact, thereby minimizing disease transmission. Essential oils are natural volatile substances from plants used as protective measure against blood-sucking mosquitoes. Methods: Twenty-three essential oils were evaluated for their repellent effect against Ae. aegypti female mosquito in laboratory conditions using Y-tube olfactometer.  Results: The essential oils exhibited varying degree of repellency. Litsea oil showed 50.31%, 60.2 %, and 77.26% effective mean repellency at 1 ppm, 10 ppm and 100 ppm respectively, while DEET exhibited 59.63%, 68.63%, 85.48% and DEPA showed 57.97%, 65.43%, and 80.62% repellency at respective above concentrations. Statistical analysis revealed that among the tested essential oils, litsea oil had effective repellency in comparison with DEET and DEPA against Ae. aegypti mosquito at all concentration. Essential oils, DEET and DEPA showed significant repellence against Ae. aegypti (P< 0.05) at all 3 concentration tested. Conclusion: Litsea oil exhibited effective percentage repellency similar to DEET and DEPA. The essential oils are natural plant products that may be useful for developing safer and newer herbal based effective mosquito repellents

Midgut Microbial Community of <i>Culex quinquefasciatus</i> Mosquito Populations from India

<div><p>The mosquito <i>Culex quinquefasciatus</i> is a ubiquitous species that serves as a major vector for west nile virus and lymphatic filariasis. Ingestion of bloodmeal by females triggers a series of physiological processes in the midgut and also exposes them to infection by these pathogens. The bacteria normally harbored in the midgut are known to influence physiology and can also alter the response to various pathogens. The midgut bacteria in female <i>Cx. quinquefasciatus</i> mosquitoes collected over a large geographical area from India was studied. Examination of 16S ribosomal DNA amplicons from culturable microflora revealed the presence of 83 bacterial species belonging to 31 bacterial genera. All of these species belong to three phyla i.e. Proteobacteria, Firmicutes and Actinobacteria. Phylum Proteobacteria was the most dominant phylum (37 species), followed by Firmicutes (33 species) and Actinobacteria (13 species). Phylum Proteobacteria, was dominated by members of γ-proteobacteria class. The genus <i>Staphylococcus</i> was the largest genus represented by 11 species whereas <i>Enterobacter</i> was the most prevalent genus and recovered from all the field stations except Leh. Highest bacterial prevalence was observed from Bhuj (22 species) followed by Nagrota (18 species), Masimpur (18 species) and Hathigarh (16 species). Whereas, least species were observed from Leh (8 species). It has been observed that individual mosquito harbor extremely diverse gut bacteria and have very small overlap bacterial taxa in their gut. This variation in midgut microbiota may be one of the factors responsible for variation in disease transmission rates or vector competence within mosquito population. The present data strongly encourage further investigations to verify the potential role of the detected bacteria in mosquito for the transmission of lymphatic filariasis and west nile virus. To the best of our knowledge this is the first study on midgut microbiota of wild <i>Cx. quinquefasciatus</i> from over a large geographical area.</p></div

Pair wise matrix of common species (Upper half) and Sφrrensen similarity index (Lower half).

<p>Pair wise matrix of common species (Upper half) and Sφrrensen similarity index (Lower half).</p

Collection sites of <i>Culex quinquefasciatus</i> mosquito in India.

<p>1: Jamnagar(JMN), 2: Bhuj(BHJ), 3: Barmer(BAR), 4: Jodhpur(JOD), 5: Bathinda(BHT), 6: Amritsar(ASR), 7: Nagrota(NAG), 8: Leh(LEH), 9: Hathigarh(HGR), 10: Masimpur(MSM).</p

of bacterial species identified from <i>Cx. quinquefasciatus</i> midgut and their occurrence in each location with their sequence accession number.

<p>of bacterial species identified from <i>Cx. quinquefasciatus</i> midgut and their occurrence in each location with their sequence accession number.</p

showing occurrence of bacterial taxa identified, Good's coverage and diversity indices at 10 different field stations.

<p>showing occurrence of bacterial taxa identified, Good's coverage and diversity indices at 10 different field stations.</p