Social communication activates the circadian gene Tctimeless in Tribolium castaneum.

Chemical communication via pheromones is an integral component in insect behavior, particularly for mate searching and reproduction. Aggregation pheromones, that attract conspecifics of both sexes, are particularly common and have been identified for hundreds of species. These pheromones are among the most ecologically selective pest suppression agents. In this study, we identified an activating effect of the aggregation pheromone of the red flour beetle, Tribolium castaneum (Herbst) (Coleoptera: Tenibroidae) on a highly conserved circadian clock gene (Tctimeless). Tribolium castaneum is one of the most damaging cosmopolitan pest of flour and other stored food products. Its male produced aggregation pheromone, 4,8-dimethyldecanal (DMD), attracts both conspecific males and females and is used for pest management via monitoring and mating disruption. The Tctimeless gene is an essential component for daily expression patterns of the circadian clock and plays vital roles in eclosion, egg production, and embryonic development. In this study, we demonstrate that constant exposure to the species-specific aggregation pheromone led to Tctimeless up-regulation and a different pattern of rhythmic locomotive behavior. We propose that changing the well-adapted "alarm clock", using DMD is liable to reduce fitness and can be highly useful for pest management.

Prevalence and transmission potential of Wolbachia in Aedes albopictus population circulating in endemic coastal districts of Odisha, India.

Wolbachia, known for its reproductive manipulation capabilities in insects, are being implemented to control dengue and chikungunya. To understand Wolbachia biology and its utility as a bio-control for vector mosquito's populations, we investigated its dissemination pattern in field in collected Ae. albopictus along with its maternal transmission efficacy over generations in regions of endemic dengue (DENV) transmission. Field collected Ae. albopictus were subjected to PCR for Wolbachia screening. Overall mean Wolbachia infection frequency in Ae. albopictus was found out to be 87.3% wherein a trend was observed in the pattern of maternal transmission across generations. χ2 for trend revealed a significant variation between Wolbachia infections and non-infections in Ae. albopictus generations. Linear regression analysis revealed the involvement of a strong negative correlation, implying that overall Wolbachia infection tends to decrease in places with high dengue cases.The reduction in Wolbachia infection frequency may be attributed to several environmental factors with the probability of being the cause for endemicity of dengue in the studied areas.This study reports on the transmission efficacy of naturally occurring Wolbachia in successive generations of Ae. albopictus and its correlation with dengue cases in clusters of Odisha, India. Studying the transmission trend of Wolbachia along with transovarial transmission of DENV might be indicative towards the interplay of Wolbachia infection in presence/absence of DENV.

Implementation of molecular method in routine malaria diagnosis and entomological studies.

BACKGROUND & OBJECTIVES: Molecular methods for malaria vector species and parasite identification have received great attention in recent years. Accurate and precise identification of the target species has direct medical and practical implications, such as in malaria diagnosis and vector dynamics study. Translation of molecular techniques will help in evaluation of epidemiological and entomological profile of malaria even in highly inaccessible areas where there is lack of an expert microscopist or entomologist. METHODS: In the present study, we have developed a simple yet accurate molecular tool for malaria diagnosis as well as for malaria vector studies. We have standardized, simplified and improvised the DNA isolation (using Chelex; a cationic exchanger), its storage and multiplex PCR for parasite detection from dried blood spot (DBS) filter paper as well as malaria vector identification and infection status study. RESULTS: The chelex-PCR based molecular method was highly sensitive (sensitivity >90%) and specific (specificity >80%) for parasite detection as well as vector species identification. This method has proven readily adaptable for use in the clinical diagnostic/research laboratory for epidemiological investigation and vector dynamics study that can challenge the conventional gold standard approach such as microscopy/ morphological methods not only in response to accuracy but also in relation to cost, time and technical expertise. INTERPRETATION & CONCLUSION: Transfer of this molecular technology from laboratory to field condition is highly essential for its availability to the common public rather than being restricted to only academic research. This can be achieved by implementation of the technology in terms of conducting mass training and awareness programs in various resource-limited endemic zones for the purpose of malaria elimination.

Wolbachia Population in Vectors and Non-vectors: A Sustainable Approach Towards Dengue Control.

Wolbachia is gram negative obligate endosymbiont known for reproductive manipulation in the host. It is important to study the presence of natural Wolbachia in mosquitoes which can later help in understanding the effect of transfected strain on indigenous strain. With this view, the present study is undertaken to focus on the prevalence, diversity, infection frequencies, phylogeny and density of indigenous Wolbachia strains in wild mosquito species of Odisha. Our study confirms Wolbachia presence in Ae. albopictus, Cx. quinquefasciatus, Cx. vishnui, Cx. gelidus, Ar. subalbatus, Mn. uniformis, and Mn. indiana. Wolbachia in the above mosquitoes were separated into two supergroups (A and B). Ae. albopictus, the major vector of dengue and chikungungunya had both super-infection and mono-infection. The ovaries of Ae. albopictus were highest in density of Wolbachia as compared to midguts or salivary glands. wAlBA and wAlbB density were variable in mosquitoes of F1 generation for both the sex and at different age. We also found that Wolbachia super-infection in females tends to increase whereas wAlbA density reduced completely as compared to wAlbB in males when they grew old. Giemsa stained squashed ovaries revealed pink pleomorphic Wolbachia cells with different shapes and forms. This study is unique in its kind covering the major aspects of the endosymbiont Wolbachia and focusing on its potential as a biocontrol agent in arboviral outbreaks. Knowledge on potential of the indigenous strain and interactions between Wolbachia and viruses can be utilized further to reduce the global burden of vector borne diseases.

Cyclic lipopeptide biosurfactant from Bacillus tequilensis exhibits multifarious activity.

Bacillus tequilensis strain CH had been previously shown to produce a biosurfactant. In this study, chemical structure of the purified biosurfactant was determined by using high performance liquid chromatography and liquid chromatography-mass spectroscopy as a 10 amino acid cyclic lipopeptide (CL). The cyclic lipopeptide was found to be active against Anopheles culicifacies larvae with a LC50 of 110 µg/ml in 2 days. 1 ppm cadmium (Cd) which had a profound mutagenic effect on the cell division of onion (Allium cepa) root tip cell resulting in abnormal metaphase, abnormal anaphase and nuclei elongation was partially reversed in the presence of 0.1 mg/ml of CL (52% cells dividing normally and 8% with abnormal division) and was comparable to control experiment where no Cd was present. Thus, the CL described in this report may have applications in eliminating larvae from water repository systems and in reversing the effects of cadmium pollution.

Insecticide susceptibility status of invasive Aedes albopictus across dengue endemic districts of Odisha, India.

BACKGROUND: Aedes albopictus is currently the most invasive mosquito species in the world. Keeping in view the wide emergence of insecticide resistance, it is imperative to focus on the current susceptibility status for various insecticides in Ae. albopictus. This study focused on understanding the insecticide resistance mechanism of Ae. albopictus collected from dengue-endemic districts of Odisha. RESULTS: Insecticide resistance was evaluated by using standardized bioassay kits (WHO) and biochemical analysis. Larval bioassays revealed the highest level of resistance from Jaipur (JP) population with a RR50 of 15.3 and LC50 of 1.177 ppm compared with an LC50 of 0.077 for the susceptible strain LabS. Results indicated the presence of dichlorodiphenyltrichloroethane resistance in the majority of adult populations. Elevated activity of nonspecific esterases and cytochrome P450s MFO indicated probable resistance to organophosphates and pyrethroids. Molecular screening for common insecticide target-site mutations confirmed the absence of the 'knockdown resistance' response for pyrethroid insecticide in Ae. albopictus population, suggesting its continual effectiveness as the major insecticide of significant importance in future vector-control programmes. CONCLUSION: This is the first report of a kdr mutation in Ae. albopictus in India and highlights the need for intensive research on other unexplored target-site mutations that might also contribute to pyrethroid resistance. Effective management and sustainable use of insecticides can be implemented by understanding resistance mechanisms and development of appropriate diagnostic tools. © 2017 Society of Chemical Industry.

Development, standardization and validation of molecular techniques for malaria vector species identification, trophic preferences, and detection of Plasmodium falciparum.

BACKGROUND & OBJECTIVES: Knowledge on prevalence of malaria vector species of a certain area provides important information for implementation of appropriate control strategies. The present study describes a rapid method for screening of major Anopheline vector species and at the same time detection of Plasmodium falciparum sporozoite infection and blood meal preferences/trophic preferences. METHODS: The study was carried from February 2012 to March 2013 in three seasons, i.e. rainy, winter and summer in Jhumpura PHC of Keonjhar district, Odisha, India. Processing of mosquitoes was carried out in two different methods, viz. mosquito pool (P1) and mosquito DNA pool (P2). Pool size for both the methods was standardized for DNA isolation and multiplex PCR assay. This PCR based assay was employed to screen the major vector com- position in three different seasons of four different ecotypes of Keonjhar district. Pearson's correlation coefficient was determined for a comparative analysis of the morphological identification with the pool prevalence assay for each ecotype. RESULTS: A pool size of 10 was standardized for DNA isolation as well as PCR. PCR assay revealed that the average pool prevalence for all ecotypes was highest for An. annularis in winter and summer whereas for An. culicifacies it was rainy season. Foothill and plain ecotypes contributed to highest and lowest vectorial abundance respectively. The results of the prevalence of vector species in pool from PCR based assay were found to be highly correlated with that of the results of morphological identification. INTERPRETATION & CONCLUSION: Screening by pool based PCR assay is relatively rapid as compared to conventional identification and can be employed as an important tool in malaria control programmes.

Wolbachia: A biological control strategy against arboviral diseases.

Vector-borne diseases particularly those transmitted by mosquitoes like Dengue are among the leading causes of mortality and morbidity in human population. There are no effective vaccines or treatment against dengue fever till date and the control methods are limited. So, new approaches are urgently in need to reverse these trends. Vector control is currently the primary intervention tool. Strategies that reduce or block pathogen transmission by mosquitoes have been proposed as a means of augmenting current control measures to reduce the growing burden of vector-borne diseases. Wolbachia an endosymbiont of arthropod vectors is being explored as a novel ecofriendly control strategy. Studies in Drosophila have shown that Wolbachia can confer resistance to diverse RNA viruses and protect flies from virus-induced mortality. This review was focused on biology of the Wolbachia and its implication as a control measure for arboviral diseases mainly Dengue and Chikungunya.

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.