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The present study larvicidal activities of hexane, chloroform, ethyl acetate, acetone and methanol extracts of Halimeda macroloba, Decsne, Caulerpa racemosa (Frosk) Weber-Van-Bosses and Ulva lactuca Lin, (Chlorophyceae) against Aedes aegypti. The marine macro green algae extracts were tested against early 4 th instar larvae of A. aegypti using WHO protocol and concentrations of 200, 400, 600,800 and 1000 ppm. The observed mortality was made 24 and 48 h after treatment, data was subjected to probit analysis to determine the lethal concentration (LC₅₀ and LC₉₀) of the treated larvae of the tested species. Among the tested extracts the maximum efficacy was observed in the ethyl acetate extracts. The ethyl acetate extracts of the seaweeds showed the presence of terpenoids, tannins and phenolic compounds stronger than the other extracts. The results revealed that all the extracts showed varied levels of larvicidal activity against A. aegypti tested. However, the ethyl acetate extract of C. racemosa showed remarkable larvicidal activity against A. aegypti (LC₅₀=579.9 and LC₉₀=1255.4 ppm values at 24 h and LC₅₀=495.4 and LC₉₀=1073.9 ppm at 48 h) followed by U. lactuca (LC₅₀=588.1 and LC₉₀=1290.7 ppm values at 24 h, and LC₅₀= 530.8, and LC₉₀= 1160.0 ppm at 48 h), respectively. The lowest larval mortality was observed with hexane extract of H. macroloba against A. aegypti with values of LC₅₀=1116.8 and LC₉₀= 1824.5 ppm (after 24 h) and LC₅₀=1059.9 and LC₉₀=1768.3 ppm (after 24 h). The present studies indicate that the larvicidal activity and phytochemicals derived from the ethyl acetate extract of C. racemosa have the potential to be used as an ideal eco-friendly approach and effective mosquito vector control agent.
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Anopheline mosquitoes and the malaria scourge

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The high prevalence of malaria in Africa has defiled many strategies aimed at its eradication. Researchers from various fields have tried without success in this fight against mosquito and its malaria disease. Annually billions of dollars are spent in the design of programs which are aimed at combating this dreaded disease. However all this spending seems to go down the drain as malaria and its vector mosquitoes celebrate their unflinching victory. Current control measures focusing on ways of preventing the disease vis- a -vis, protect man from the vectors “anopheline mosquito” are the mainstay of malaria prevention and control. Many of these control measures are operational with each contributing in its little way. The use of Long Lasting Insecticide Treated Nets (LLITN) and Indoor Residual Sprays (IRS) are well established strategies with global recognition and currently ongoing in Africa. However, as a result of shortcomings in these major control measures, new strategies with hopes of blissful success are been sought after. Larviciding (abortion of metamorphosis) and constant and adequate environmental sanitation seems to be the next option available for use. This article therefore takes a look at the vector- anopheline mosquito, its ecology, productivity and distribution. It also considers malaria and the various control and preventive measures currently targeted at its eradication.
Th e present exploration is focused on the bio-fabrication of silver nanoparticles (Ag NPs) using Trichodesma indicum aqueous leaf extract as a reducing agent. Th e synthesized Ag NPs were productively characterized by UV-vis spectroscopy, XRD, and TEM studies. Th e photosynthesis of Ag NPs was done at room temperature for 24 h and at 60°C. Th e green synthesis of spherical-shaped Ag NPs bio-fabricated from T. indicum with a face centred cubic structure showed average particle sizes of 20–50 nm, which is inconsistent with the particle size calculated by the XRD Scherer equation and TEM analysis. We further explored the larvicidal effi cacy of biosynthesized Ag NPs with leaf extracts of T. indicum against Mythimna separata. Th e results showed that Ag NPs (20–50 nm) of T. indicum possess good larvicidal activity against M. separata with an LC50 of 500 ppm. Th us, we can advocate that Ag NPs of 20–50 nm size extracted from T. indicum may be considered in the pest management programme of M. separata in future.
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