Chironomus Circumdatus Research Articles

Evaluation of larvicidal efficacy of Diospyros montana leaf extract on Aedes albopictus

In tropical and subtropical countries, mosquitoes play vital role as vectors of numerous dangerous diseases, such as dengue, yellow fever, filariasis, malaria, and zika, among others. Aedes albopictus, the Asian tiger mosquito can transmit the viruses of several life threatening diseases including, dengue, yellow fever, and zika. The present study aimed at assessment of the larvicidal activity of the crude extract of Diospyros montana leaves against Ae. Albopictus, and identification of the plant compound and functional groups responsible for larvicidal efficacy via FT-IR and different phytochemical analysis. Effect on the non-target organisms was also evaluated. However, more than 80% larval mortality is observed after 72 hours of exposure in all instars. After 72 hours of exposure, the LC50 caused moderate mortality of 12% and 8% against Chironomus circumdatus and Toxorhynchites splendens respectively. Numerous secondary metabolites, including terpenoids, saponins, flavonoids, and alkaloids, coumarins were present in the crude extract of D. Montana. This is the first study to examine the efficacy of D. Montana leaf extract as a larvicidal agent against Ae. albopictus through determination of its secondary metabolites.

Chironomids diversity of Manipur

Chironomids are Diptera and these are good bioindicators of aquatic habitats, and serve as food of aquatic as well as the lower terrestrial animals. The diversity of these were assessed from the Dhanamanjuri University Campus, which revealed three genera and one unidentified genus viz., Kiefferulus calligaster, Chironomus plumosus, Chironomus circumdatus and one morphotype closely resembling Yama (Yama type). The chromosome compliments of these were observed to be with 2n=8 (K. calligaster- AB, CD, EF, G; C. plumosus- AB, CD, EF, G; C. circumdatus- BF, CD, AE, G and Yama type- AE, BF, CD, G). The differences were in the translocation both in NOR and chromosomes. Kiefferulus calligaster, C. plumosus, Yama type and C. circumdatus were observed coexisting in cemented drainage, with Yama type being predominant in the pond; the latter was mainly collected from more contaminated ditches with domestic waste. The polytene chromosomes were species-specific and could be utilized to identify the species in the larval forms.

Mining the diversity and functional profile of bacterial symbionts from the larvae of Chironomus circumdatus (bloodworms)

Chironomids are the most abundant aquatic insects in freshwater habitats that can survive in extreme conditions. In this study, as the microbiome provides extended genotype to the host to perform various functions, we explored the microbiota of the Chironomus circumdatus larvae to find out the putative role played by the symbiotic bacteria for the host. The metabarcoding analyses of the larvae revealed that the insect harbors 1771 phylotypes. Out of the various microbial communities found, the majority corresponded to the phyla Proteobacteria (52.59%) and Actinobacteria (20.56%), respectively. The midges also harbored Klebsiella (2.57%), Enterobacter (1.32%), Bacillus (2.29%), and Acinetobacter (2.13%) genera that are involved in detoxification of xenobiotics present in the water. The presence of radiation-resistant genera like Deinococcus, including bacterial species like radiodurans, a highly radiation-resistant bacterium, indicates its potential to support the host's ability to sustain in adverse environments. The functional profiling of the bacteria showed the relative abundance of many enzyme groups, such as transferases (40.62%), oxidoreductases (23.49%), and hydrolases (3.77%). The results indicate that the larvae harbor a considerable variety of bacteria that help the host adapt and survive in the polluted waters. The present study provides thorough insights into the microbiome of the C. circumdatus larvae that can be exploited for the bioremediation of certain pollutants through biomimetic strategies. It also gives us a wake-up call to take a good look at the guts of these disease-carrying insects' inabilities to spread deadly human diseases.

Larvicidal potential of rhizome extracts of Elettaria cardamomum (L.) Maton against filarial vector, Culex quinquefasciatus Say, 1823 (Diptera: Culicidae)

Investigation on the larvicidal potential of Elettaria cardamomum (L.) Maton rhizome extracts against filarial vector, Culex quinquefasciatus Say, was undertaken with crude concentrations 0.1-0.5 per cent and 40, 50, and 60 ppm of each of petroleum ether, hexane and ethyl acetate rhizome extracts revealed that first instar larvae were most susceptible to crude rhizome extract with 100 per cent mortality at 0.5% after 24 hrs of exposure. Among three solvent extracts, ethyl acetate extract showed maximum mortality (96.66±3.33%) at 60 ppm after 72 hrs of exposure. LC50 values of larvicidal bioassays by crude rhizome extract were 0.1002, 0.0794, 0.1275 and 0.6334 ppm for 1st, 2nd, 3rd and 4th instars larvae after 72 hrs of exposure, respectively and LC50 values for larvicidal bioassays by petroleum ether, hexane, and ethyl acetate rhizome extracts were 48.3629, 40.9613 and 37.0282 ppm against 3rd instar larvae after 72 hrs of exposure, respectively. Preliminary phytochemical analyses of the rhizome extracts showed presence of secondary metabolites. Non target organisms, tadpoles of frog and 4th instar larvae of Chironomus circumdatus, were not affected by the crude as well as ethyl acetate rhizome extracts. Larvicidal efficacy of the rhizome extracts of E. Cardamomum against Cx. quinquefasciatus mosquito species has been reported first time.

Bio-based versus synthetic: comparative study of plasticizers mediated stress on Chironomus circumdatus (Diptera-Chironomidae).

Phthalates are used as plasticizers in products made of polyvinyl chloride to increase the flexibility of polymers. Unfortunately, these are known to cause adverse effects on living organisms, and also, fast depletion of petroleum resources calls for the exploration of alternatives as replacements. Recent developments in bio-based plasticizers have led to their use as additives for various applications. As they have received much attention in the past decade, it is crucial to study the effects of these plasticizers on living organisms. Hence, we tried to compare the effects of synthetic plasticizer dioctyl phthalate and bio-based plasticizer ethanolamine on Chironomus circumdatus larvae. Mortality was achieved at a lethal concentration (LC50) value of 0.385 mg/L for ethanolamine and dioctyl phthalate at 0.125 mg/L. Disruption in the level of metabolites along with lipid peroxidation was observed in the larvae exposed to plasticizer mediated stress. To overcome these changes, an increase in the levels of antioxidant enzymes such as Superoxide Dismutase, Catalase, Glutathione Peroxidase and Glutathione Reductase, as well as in the levels of detoxifying enzymes like Glutathione-S-Transferase, Esterases and Mixed Function Oxidase during post-exposure recovery conditions was seen. Alterations in the expression levels of heat shock protein 70 and ecdysone receptor genes were also observed. From the comparative study, it could be concluded that Chironomus circumdatus larvae, to a certain extent, have developed tolerance to both ethanolamine and dioctyl phthalate mediated stress. However, dioctyl phthalate has led to more stress as compared to ethanolamine in these larvae.

Evaluation of mosquito larvicidal activity of Azolla pinnata leaf extracts against the filarial vector Culex quinquefasciatus

Vector control is a major challenge now-a-days when they became resistance against commonly available insecticides. As an alternative, preliminary laboratory evaluation of Azolla pinnata crude and chloroform: methanol solvent extract was carried out under laboratory trials for control of Culex quinquefasciatus. Crude and solvent extract (chloroform: methanol) extracts of A. pinnata leaves were examined for the larvicidal activity against all the larval instars (1st to 4th) of C. quinquefasciatus. Dose-dependent mortality assays were performed using the extracts. Further, determinations of LC50 and LC95 values were accomplished through log-probit analyses and regression analyses. The larvicidal activity was statistically justified through ANOVA analyses. Effects of the extracts were examined on non-target water fauna. Exposure to A. pinnata crude and chloroform: methanol extract increased the mortality of first to fourth-instar C. quinquefasciatus. All the graded concentrations showed significant (P <0.05) larval mortality and the results of the regression equation revealed that the mortality rates were positively correlated with the concentrations of the extracts (R2 close to 1). LC50 values of all instars after 24 h of exposure were between 86.99-294.06 ppm for crude and 48.87-111.44 ppm for chloroform: methanol extract. Chloroform: methanol extract is better than crude because the nature of biological components can be enhanced in presence of solvent and secondly the stronger extraction capacity could have produced a greater number of active constituents. The residual effect is noted even at the end of 72 h. A negligible toxicity to the larvae of Chironomus circumdatus was noticed as non-target organisms.

Comparative Microbiota Composition Across Developmental Stages of Natural and Laboratory-Reared Chironomus circumdatus Populations From India.

Chironomids are aquatic insects that undergo a complete metamorphosis of four life stages. Here we studied, for the first time, the microbiota composition of Chironomus circumdatus, a tropical midge species, both from the Mula and Mutha Rivers in Pune, India and as a laboratory-reared culture. We generated a comparative microbial profile of the eggs, larvae and pupae, the three aquatic life stages of C. circumdatus. Non-metric multidimensional scaling analysis (NMDS) demonstrated that the developmental stage had a more prominent effect on the microbiota composition compared to the sampling location. Notably, the microbiota composition of the egg masses from the different sampling points clustered together and differed from laboratory culture larvae. Proteobacteria was the dominant phylum in all the environmental and laboratory-reared egg masses and pupal samples, and in the laboratory-reared larvae, while Fusobacteria was the dominant phylum in the larvae collected from the field environment. The most abundant genera were Cetobacterium, Aeromonas, Dysgonomonas, Vibrio, and Flavobacterium. The ten amplicon sequence variants (ASVs) that most significantly contributed to differences in microbiota composition between the three sampled locations were: Burkholderiaceae (ASVs 04 and 37), C39 (Rhodocyclaceae, ASV 14), Vibrio (ASV 07), Arcobacter (ASV 21), Sphaerotilus (ASV 22), Bacteroidia (ASVs 12 and 28), Flavobacterium (ASV 29), and Gottschalkia (ASV 10). No significant differences were found in the microbial richness (Chao1) or diversity (Shannon H’) of the three sampled locations. In contrast, significant differences were found between the microbial richness of the three life stages. Studying the microbiota of this Chironomus species may contribute to a better understanding of the association of C. circumdatus and its microbial inhabitants.

Characterization of an Esterase Producing Bacterium from the Gut of Chironomus circumdatus (Bloodworms) and its Ability to Use Modified Phthalates.

Insects harbor bacteria that are a rich source of enzymes that can be utilized for various industrial and biotechnological applications. It is predicted that during evolution these detoxifying enzymes have been acquired by insects through bacteria. However, the role of host insect detoxification enzymes has already been extensively studied but only a few resistance development studies have been focused on the enzymes derived from gut bacteria. Thus in this study, two bacterial isolates were found in the gut of Chironomous circumdatus larvae having esterase activity, out of which one bacterium was molecular characterized and it was found to be Enterobacter mori designated as strain BI1245. Further, crude extract from the bacterium was characterized and it was observed that it showed maximum activity at pH 8 and temperature 60°C. Moreover, the crude extract showed 0.26mM and 290 U/mgof protein as Km and Vmax value when p-nitrophenyl acetate was used as a substrate. Thereafter, the bacterial isolate was incubated in minimal salts medium containing modified phthalates and it was found that bacterium could utilize shorter alkyl-chain phthalic acid esters faster as compared to long alkyl chains thereby indicating that side chain of the substrates has a significant effect on the utilization of phthalic acid esters. Thus the gut flora present in insects may play an important role in providing resistance to the host to live in phthalate polluted water.

Identification and Confirmation of Chironomus circumdatus Kieffer, 1916 (Diptera: Chironomidae) Using DNA Barcoding

Present study was performed to identify and confirm collected larval Chironomid up to species level. To assess molecular taxonomy and phylogeny, DNA barcoding was done using Sanger dideoxy sequencing of mitochondrial cytochrome c oxidase subunit I (COI) gene of larval sample. Bioinformatics analysis was done by using NCBI’s BLAST software. By evidence of DNA barcoding, it was confirmed that present larval chironomid species was Chironomus circumdatus Kieffer, 1916.

Identification of chironomid species as natural reservoirs of toxigenic Vibrio cholerae strains with pandemic potential.

Vibrio cholerae causes the fatal cholera diarrhea. Chironomids (Diptera; Chironomidae) are abundant in freshwater aquatic habitats and estuaries and are natural reservoirs of V. cholerae. Until now, only the non-O1/O139 serogroups of V. cholerae were identified in chironomids. Here, we explored whether chironomids are natural reservoirs of V. cholerae O1/O139 serogroups, which are associated with cholera endemics and pandemics. All four life stages of chironomids were sampled from two rivers, and a laboratory culture in Pune, India, and from a pond in Israel. In total, we analyzed 223 chironomid samples. The presence of V. cholerae O1/O139 serogroups was verified using molecular tools. Nine chironomid species were identified; of them, Chironomus circumdatus was the most abundant. The presence of V. cholerae serogroup O1 and the cholera toxin genes were detected in samples from all chironomid species. However, serogroup O139 was detected in only two chironomid species. Besides PCR to detect specific genes, a metagenomic analysis that was performed in three selected C. ramosus larvae, identified a list of virulence genes associated with V. cholerae. The findings provide evidence that chironomids are natural reservoirs of toxigenic V. cholerae O1/O139. Chironomid populations and V. cholerae show biannual peak patterns. A similar pattern is found for cholera epidemics in the Bengal Delta region. Thus, we hypothesize that monitoring chironomids in endemic areas of the disease may provide a novel tool for predicting and preventing cholera epidemics. Moreover, serogroup O139 was detected only in two chironomid species that have a restricted distribution in the Indian subcontinent, possibly explaining why the distribution of the O139 serogroup is limited.

Biochemical and molecular changes mediated by plasticizer diethyl phthalate in Chironomus circumdatus (bloodworms)

Plasticizers are used as additives in making plastics. Diethyl phthalate (DEP) is one of the majorly used plasticizers in various products. When plastic materials are dumped in an aquatic system, there is an increase in chances of DEP leaching out and getting deposited in water. Thus the current work focuses on studying the effect of DEP on the larval stages of Chironomus circumdatus. In this study it was found that there was an increase in lipid peroxidation levels indicating imposition of oxidative stress on these larvae due to the exposure of DEP. Changes in the levels of carbohydrates and lipids were also seen. To reduce these effects antioxidant defense system may get activated. Thus investigations showed an increase in enzymatic activity of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx) and acetylcholinesterases (AchE) and decrease in the activity of glutathione reductase (GR). Nonenzymatic antioxidant glutathione levels were also increased during the post-recovery exposure period. Thus this indicates that both enzymatic, as well as non-enzymatic antioxidants, play a certain role in reducing the stress mediated by DEP. Up-regulation of gene expression of heat shock protein70 (hsp70) was observed, which is one of the conserved protein produced during stress response in many dipterans. Changes in the level of expression of the ecdysone receptor (EcR) gene were also seen in DEP exposed larvae. Thus the insights give us a preliminary indication that physiological and developmental adaptations may take place in these organisms to persist in the DEP contaminated environment. CapsuleDEP mediated stress imposes changes in the metabolites and thus activation of antioxidant defense system in aquatic midges of Chironomus circumdatus. Changes in the expression of heat shock protein70 and ecdysone receptor was also seen indicating that DEP mediated stress affects at the molecular level also of the organism. These changes may help them to tolerate and live in DEP polluted water.

Larvicidal potentiality of the leaf extracts of Glochidion lanceolarium (Phyllanthaceae) against the Japanese encephalitis vector Culex vishnui (Culicidae)

ABSTRACTTo save human population from mosquito-borne diseases, control of mosquito is the first and foremost step. This study was carried out to evaluate larvicidal activities of Glochidion lanceolarium (Roxb.) Voigt. (Phyllanthaceae) leaf extracts against the Japanese encephalitis vector Culex vishnui Theobald, 1901 (Culicidae). Crude and three different solvent extracts (petroleum ether, ethyl acetate and acetone) of G. lanceolarium leaves were applied for larvicidal bioassay against all larval instars of Cx. vishnui. For statistical justifications, log-probit analysis, regression analysis and analysis of variance (ANOVA)were performed. Impacts of both extracts on non-target water fauna were also evaluated. Bioactive compound was subjected to infrared (IR) spectroscopy analysis for chemical characterisation of active ingredient after thin-layer chromatography (TLC). A total of 0.5% concentration of crude extract showed highest larval mortality after 72 h of exposure. Among the three tested solvent extracts, ethyl acetate extracts exhibited the most potent larvicidal activity. In ethyl acetate extract, 100% mortality was found in 80 ppm concentration against the first instar larvae after 72 h of exposure. However, the non-target organism Chironomus circumdatus Kieffer, 1916 (Chironomidae) was found safe to the extracts. IR spectroscopy analysis revealed the presence of phenol as a functional group. G. lanceolarium leaves have remarkable larvicidal efficacy against the Cx. vishnui.Abbreviations: Glochidion lanceolarium – G. lanceolarium Culex vishnui – Cx. vishnui IR Spectroscopy - Infrared Spectroscopy TLC - Thin-Layer Chromatography JE - Japanese Encephalitis ANOVA – Analysis of Variance Chironomus circumdatus – C. circumdatus WHO – World Health Organization LC50 – Leather Concentration 50 RH - Relative Humidity Rf - Retardation factor DMSO - Dimethyl Sulphoxide SE - Standard Error

Effects of Three Selected Pesticides on the Non-Biting Midges (Diptera: Chironomidae) in Rice Agro-Ecosystem of an area of West Bengal; India

Deformities of non biting midge larvae’s mouthparts are considered as indicators of environmental degradation that caused by water pollutants like pesticides, heavy metals, organic contaminants etc. The present investigation was aimed to assess the effects of 3 pesticides, viz. Cartap Hydrochloride, Carbofuran and Fipronil on deformities of chironomid larvae of the Rice fields of Village Dhunui; Memari Block-II of Burdwan district in West Bengal. The study area is dominated by the species of the genus Chironomus of chironomid community. Concurrently six (6) species were considered. The average percentage of mouthpart deformities was 14% in all chironomid larvae. Highest degree of malformation was noticed in Chironomus circumdatus in which more than 18.90% of all specimens were affected. However, further investigative efforts are essential to investigate the actual explanation in support of the occurrence of high degree of deformities in chironomid.

One pot synthesis of silver nanocrystals using the seaweed Gracilaria edulis: biophysical characterization and potential against the filariasis vector Culex quinquefasciatus and the midge Chironomus circumdatus

Mosquitoes (Diptera: Culicidae) represent a deadly threat for millions of humans and animals worldwide. Seaweeds are an important resource for marine biotechnology and are currently investigated as sources of reducing and capping agents for the nanosynthesis of mosquitocides. Culex quinquefasciatus is a major vector of lymphatic filariasis, while chironomid midges (Diptera: Chironomidae) elicit allergic reactions. In this research, silver nanoparticles (AgNP) were biosynthesized using a cheap aqueous extract of Gracilaria edulis as reducing and stabilizing agent. The formation of AgNP was confirmed by UV–Vis spectrophotometry. AgNP were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), and energy dispersive X-ray analysis. AgNP were mostly spherical and cubic in shape, crystalline in nature. Gracilaria edulis-synthesized AgNP showed excellent ovicidal, larvicidal, pupicidal, and ovideterrent toxicity against Cx. quinquefasciatus and Chironomus circumdatus. Larvicidal LC50 ranged from 17 to 29 ppm. AgNP of 30 ppm led to 100 % mortality in treated eggs. Doses higher than 10 ppm lead to oviposition deterrence rates higher than 75 % (Oviposition Activity Index lower than −0.59). In the field, a single application of AgNP (10 × LC50) led to elimination of larval populations of Cx. quinquefasciatus and Ch. circumdatus within 72 h. Overall, G. edulis-synthesized AgNP may be potential candidates to develop eco-friendly control tools against Diptera of medical and veterinary importance.

Mosquito larvicidal potential of ethanol leaf extract of the plant, &lt;i&gt;Annona reticulata&lt;/i&gt; L. &lt;i&gt;against Aedes aegypti&lt;/i&gt; L. and &lt;i&gt;Culex quinquefasciatus&lt;/i&gt; Say (Diptera: Culicidae)

The larvicidal potential of ethanol leaf extract of Annona reticulata L. (A. reticulata ), ( Annonaceae) was evaluated against 1st - 4th instars larvae of Aedes aegypti L. ( Ae. aegypti ) and Culex quinquefasciatus Say ( Cx. quinquefasciatus ) mosquitoes at 24, 48 and 72 h exposure. The extract was found more effective against Cx. quinquefasciatus than Ae . aegypti larvae and its LC 50 and LC 90 values gradually decreased with increased period of exposure. LC 50 values of the extract recorded after 24 h of exposure were 0.5021, 2.9374, 4.2048, 6.2245 ppm respectively against 1st- 4th larvae of Cx. quinquefasciatus and 6.8839, 5.9929, 14.5745, 19.8836 ppm against Ae. aegypti larvae. No mortality and any abnormal behavior up to 72 h post exposure were observed in aquatic non target organisms viz ., Chironomus circumdatus larvae, Diplonychus annulatum and tadpoles of frog when exposed to 24 h LC50 dose of the extract against 3rd instar larvae of Cx. quinquefasciatus . In conclusion, the ethanol leaf extract of A. reticulata exhibited excellent larvicidal activity against Cx. quinquefasciatus and Ae. aegypti mosquitoes.

Phytochemical extractions from the leaves of &lt;i&gt;Ravenala madagascariensis&lt;/i&gt; from Sundarban area and its effect on southern house mosquito (&lt;i&gt;Culex quienquefasciatus&lt;/i&gt; Say 1823) larvae

Vector control is a major issue mainly in this time when resistance to chemical insecticides leads to a greater problem. For an alternative measure novel botanical sources can be used as a good insecticide with less toxic hazards to the environment and public health. The present study estimated larvicidal activities of the crude and solvent extracts of Ravenala madagascariensis against the filarial vector Culex quienquefasciatus under laboratory conditions. Crude extracts of R. madagascariensis mature leaves were examined for larvicidal activity against all the larval instars (1 st to 4 th ) of Cx. quienquefasciatus. Solvent extraction was carried out using three different solvents viz. petroleum ether, chloroform: methanol (1:1 v/v) and absolute alcohol. Dose dependent mortality assays were performed using the bioactive fractions of the solvent extracts. Further, determinations of LC 50 and LC 90 values were accomplished through log-probit analyses and regression analyses. The larvicidal activity of R. madagascariensis leaves were statistically justified through ANOVA analyses. Effects of the bio-active portion were examined on the non-target water fauna. After 72 h of exposure 78.67% mortality of 1 st instars larvae was recorded at 0.5% concentration of crude extract. 150 ppm concentration of solvent extract showed 100% mortality against 1 st instars larvae after 72 h of exposure. 200 ppm concentration was responsible for 100% mortality of 2 nd instars larvae in 72 h. 250 ppm concentration showed significant mortality against 3 rd and 4 th instars larvae. Chironomus circumdatus larvae, non target organism, exhibited no significant mortality. This experimental study was an initiative to ascertain R. madagascariensis as a novel resource of target specific larvicide against Cx. quienquefasciatus larvae. Key words: Ravenala madagascariensis, Culex quienquefasciatus, non-target organisms, larvicide

Mosquito larvicidal and antimicrobial activity of synthesized nano-crystalline silver particles using leaves and green berry extract of Solanum nigrum L. (Solanaceae: Solanales)

Silver nanoparticles (AgNPs) that are synthesized by using aqueous extracts of Solanum nigrum L., is a simple, non-toxic and ecofriendly green material. The present study is based on assessments of the larvicidal and antimicrobial activities of the synthesized AgNPs from fresh leaves, dry leaves and green berries of S. nigrum against larvae of Culex quinquefasciatus and Anopheles stephensi and four human pathogenic and five fish pathogenic bacteria respectively. The synthesized nanoparticles are characterized with UV–vis spectroscopy, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and transmission electron microscope (TEM) analysis. The nanoparticles are spherical to polyhedral in shape with size of 50–100nm (average size of 56.6nm). In larvicidal bioassay with synthesized AgNPs, highest mortality are observed at 10ppm against An. stephensi with LC50 values of 1.33, 1.59, 1.56ppm and LC90 values of 3.97, 7.31, 4.76ppm for dry leaves, fresh leaves and berries respectively. Antibacterial activity test reveals better results against fish pathogenic bacteria than human pathogenic bacteria. Non target organism like Toxorhynchites larvae (mosquito predator), Diplonychus annulatum (predatory water-bug) and Chironomus circumdatus larvae (chironomid) are also exposed to respective lethal concentrations (to mosquito larvae) of dry nanoparticles and no abnormality in the non target organisms are recorded. These results suggest that the synthesized AgNPs of S. nigrum have the potential to be used as an ideal eco-friendly compound for the control of the mosquito larvae and harmful bacteria.

Evaluation of Mosquito Larvicidal Activities of Seed Coat Extract of &lt;i&gt;Cassia sophera&lt;/i&gt; L.

In the present study an attempt was made to analyze the larvicidal activity of crude and ethyl acetate extracts of matured seed coat of Cassia sophera against Culex quinquefaciatus . Crude and ethyl acetate extracts of matured seed coat of Cassia sophera was tested against Culex quinquefaciatus . The lethal concentration was determined and the appropriate lethal concentrations at 24 h for ethyl acetate extract was also studied on non target organisms such as Daphnia sp., Diplonychus annulatum (predatory water-bug) and Chironomus circumdatus larvae (insect). Phytochemical analysis of the crude extract of matured seed coat of Cassia sophera was also done. All the graded concentration (0.6%, 0.7%, 0.8%, 0.9%, 1%) showed significant (p<0.05) larval mortality and result of regression equation revealed that mortality rates were positively correlated with concentrations of extracts. LC 50 and LC 90 values were calculated at different time intervals, and the lowest values were obtained at 72 h for first instar larvae. In ethyl acetate solvent extract the mortality rate was higher at 520 ppm against Culex quinquefaciatus than the other doses. There was no mortality of non-target organism within 72 h of post exposure to LC 50 concentration at 24 h of both crude and solvent extracts under the laboratory condition. The result of preliminary qualitative phytochemical analysis of the seed coat revealed the presence of some secondary metabolite such as saponin, alkaloid and cardiac glycosides. The results support that the tested plant extract can be used for control of larval form of Culex quinquefaciatus .

Nutrient conditions and chironomid productivity in Kolkata, India: assessment for biomonitoring and ecological management

The chironomid diversity in the water bodies are useful indicators of the nutrient and environmental states. A spatial scale analysis on the relative abundance of the chironomid species in the context of selected nutrient indicators like organic carbon (C), potassium ions (K+), nitrate (NO3¯), and phosphate (PO42¯) of the water bodies was assessed to justify the use of chironomids in environmental biomonitoring. Analysis of a sample of 90 data from eight different ponds of Kolkata, India, revealed the presence of 11 chironomid species in different relative densities. The chironomid immature productivity was found to be positively correlated with C and PO42¯ of the water bodies, while no definite significant correlation was observed for K+, NO3¯. Based on these nutrients and the productivity of chironomids the ponds could be distinguished from one another. The abundance of three species of chironomid midges, Chironomus striatipennis, Chironomus circumdatus and Kiefferulus calligaster were prominent in all the water bodies. Cluster analysis showed that these species were highly correlated in their abundance contrast to others. The correspondence analysis showed distribution of the chironomid species to differ against the variance of nutrients. The results are supportive of the use of chironomid larvae in biomonitoring and ecological restoration of urban water bodies, through monitoring the nutrient status and the chironomid species assemblage. In this instance the chironomid species C. striatipennis , C. circumdatus and K. calligaster can specifically act as indicator of the nutrient state of the ponds.

Mosquito larvicidal and biting deterrency activity of bud of Polianthes tuberosa plants extract against Anopheles stephensi and Culex quinquefasciatus

ObjectiveTo evaluate the larvicide and biting deterrency activity of bud of Polianthes tuberosa (P. tuberosa) against Culex quinquefasciatus (Cx. quinquefasciatus) and Anopheles stephensi (An. stephensi). MethodsCrude and solvent extract [ethyl acetate, chloroform: methanol (1:1, v/v), acetone] of fresh, mature, bud of P. tuberosa was tested against Cx. quinquefasciatus and An. stephensi. The repellent activity tested by chloroform: methanol (1:1, v/v) solvent extract against both mosquito species. The appropriate lethal concentrations at 24 h for chloroform: methanol (1:1, v/v) extract was also studied on non target organisms such as Toxorhynchites larvae, Diplonychus annulatum and Chironomus circumdatus. ResultsIn a 72 h bioassay experiment, 0.5 % crude extract showed the highest mortality and chloroform: methanol (1:1, v/v) solvent extract showed the highest mortality, the maximum (P < 0.05) mortality was recorded at a concentration of 60 mg/L. The chloroform: methanol (1:1, v/v) solvent extract provide 4 h protection against Cx. quinquefasciatus and 5 h against An. stephensi from biting. ConclusionsBoth crude and chloroform: methanol (1:1, v/v) extract showed efficient activity against Cx. quinquefasciatus, so it could be used as a mosquito larvicide agent. There is no change in the activity of non-target organism so, it is safe to use.