A shift in resting habitat and feeding behavior of Anopheles fluviatilis sibling species in the Keonjhar district of Odisha, India.

BACKGROUND: Anopheles fluviatilis exists as a complex of sibling species S, T, U and V exhibiting distinct variations. Sibling species S is considered as the main vector and anthropogenic whereas T, U and V are zoophagic non-vectors. This study was performed in a forested village of Keonjhar district, Odisha to identify the status of An. fluviatilis sibling species. METHODS: Mosquito collections were made from cattle sheds (CS), human dwellings (HD) and mixed dwellings (MD) from June 2012 to May 2013. The proportion of An. fluviatilis collected from different habitats was compared with An. culicifacies. PCR assays were conducted to reveal their sibling species composition, host preference and sporozoite rate. RESULTS: Anopheles fluviatilis was the dominant species followed by An. culicifacies. The relative proportion of collection was high in MD and HD for An. fluviatilis and An. culicifacies respectively. PCR assay confirmed 9.4% S and 75.5% T. Mean collection of sibling species T and S were significantly high in MD and HD. Human blood index (HBI) of 0.88 and 0.61 was confirmed for sibling species S and T respectively with 13% sporozoite rate for S. CONCLUSIONS: High density of the sibling T was found in the study site with a shift in resting habitat and blood feeding preference. GenBank submissions: KJ451071.1, KJ451072.1, KJ451073.1, KJ451074.1, KJ451432.1, KJ451433.1, KJ451434.1, KJ451435.1, KJ451428.1, KJ451429.1, KJ451430.1, KJ451431.1.

Vectorial capacity and genetic diversity of Anopheles annularis (Diptera: Culicidae) mosquitoes in Odisha, India from 2009 to 2011.

Anopheles annularis is one of the major vectors of malaria in Odisha, India. The present study was undertaken to determine the vectorial capacity and assess the genetic diversity of An. annularis collected from different endemic regions of Odisha. Mosquitoes were collected from thirteen endemic districts using standard entomological collection methods from 2009 to 2011. Sibling species of An. annularis were identified by PCR-RFLP and sequencing of D3 region of 28S ribosomal DNA (rDNA) region. Plasmodium falciparum (Pf) sporozoite rate and human blood fed percentage (HBF) were estimated by multiplex PCR using Pf and human specific primers. Genetic diversity of An. annularis was estimated by ISSR markers. Out of 1647 An. annularis collected, 1353 (82.15%) were collected by mechanical aspirators and 294 (17.85%) by light trap. 49 (2.97%) were positive for human blood and 18 (1.09%) were positive for Pf sporozoite. PCR-RFLP and sequencing analyses detected only An annularis A in the study areas. Overall genetic differentiation among An. annularis populations was moderate (FST=0.048) and showed significant correlation between genetic distance and geographic distance (r=0.882; P<0.05). Angul population proved to be genetically unique and was highly divergent FST>0.110) from other populations, suggesting low gene flow between them. The study indicated that only An. annularis A was found in Odisha with potential vectorial capacity that can play a major role in malaria transmission. ISSR markers proved to be useful molecular tools to evaluate genetic variability in An. annularis populations.