Kuntal Bhattacharya

Phagodeterrence, larvicidal and oviposition deterrence activity of Tragia involucrata L. (Euphorbiaceae) root extractives against vector of lymphatic filariasis Culex quinquefasciatus (Diptera: Culicidae)

Abstract Objective To evaluate phagodeterrence or biting deterrence, larvicidal and oviposition deterrence activity of Tragia involucrata ( T. involucrata ) root extractives against Culex quinquefasciatus ( Cx. quinquefasciatus ). Methods Phagodeterrence test was done using five different solvents namely petroleum ether, benzene:ethyl acetate (1:1 v/v), chloroform:methanol (1:1 v/v), acetone and absolute alcohol against the females of Cx. quinquefasciatus . Effective deterrence was recorded. The larvicidal bioassay was performed by solvent extractives of T. involucrata roots against 1st, 2nd, 3rd and 4th instars larval forms of Cx. quinquefasciatus . Mortality rates were recorded after 24, 48 and 72 h of exposure followed by justification of LC 50 and LC 90 values at different concentrations. Finally, the larvicidal assay was ended up by recording the health belongings of non-target water fauna. Oviposition deterrence activity of root extractives was examined against the gravid females of Cx. quinquefasciatus . Results About 92.85% phagodeterrence was noticed at the level of 4% of chloroform:methanol (1:1 v/v) for the very 1st hour of exposure. Entire larval populations of 1st and 2nd instars were subjected to diminution following the treatment of 0.4% and 0.5% of benzene:ethyl acetate (1:1 v/v) root extractives respectively. While 92.33% and 78.33% mortality were recorded for 3rd and 4th instars larval forms respectively. Mean effective oviposition deterrence was found to be 97.85% at 2.5% concentration level of chloroform:methanol (1:1 v/v) root extractives. Conclusions This study is a pioneer attempt to establish phagodeterrence, larvicidal and oviposition deterrence activity of T. involucrata root extractive.

Control of human filarial vector, Culex quinquefasciatus Say 1823 (Diptera: Culicidae) through bioactive fraction of Cayratia trifolia leaf

OBJECTIVE To investigate the mosquito larvicidal activity of Cayratia trifolia (L.) Domin (Vitaceae: Vitales) (C. trifolia) which is distributed in many parts of India with medicinal properties as vector control is facing threat due to the emergence of resistance to synthetic insecticides. METHODS Young and mature leaves of C. trifolia were investigated for larvicidal activity against 3rd instars larvae of Culex quinquefasciatus in different seasons throughout the year. The active fractions were extracted using six different solvents in a non-polar to polar fashion viz petroleum-ether, benzene, chloroform: methanol (1:1 v/v), acetone, absolute alcohol and distilled water. Dose dependent mortality was recorded against each solvent extract. Determination of LD50 and LD90 were executed through log-probit analysis using the most bioactive fraction. The fluctuations in mortality were statistically co-related through ANOVA analyses concerning different seasons and types of leaves as random variables. Justification of larvicidal activity was established through students t-test. Costing effects were evaluated on the non-target water fauna under laboratory conditions. Thin layer chromatographic techniques were performed for phytochemical analysis and categorization of chemical personality of the active fractions using the most effective solvent extract following standard methods. RESULTS Significant variations in mortality rate were noted with respect to the type of leaves (mature and senescence), concentration of leaf extract and between seasons. The water extract among all the solvent extracts was found to induce cent percent mortality at 50 mg/L in test mosquito species within 24 h with a LD50 and LD90 value of 10.70 mg/L and 27.64 mg/L respectively. No significant mortality was recorded in non-target water population. Chromatographic analyses of the water extract revealed the presence of steroids, triterpene glycosides, essential oil, phenolics and diterpenes as secondary phytochemicals. CONCLUSIONS Water extract of C. trifolia leaf promised as a cost effective and potent larvicidal agent against Culex quinquefasciatus.

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

ABSTRACT To 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