Larvicidal and repellent properties of some essential oils against Culex tritaeniorhynchus Giles and Anopheles subpictus Grassi (Diptera: Culicidae)

AbstractObjectiveTo investigate the larvicidal and repellent properties of essential oils from various parts of four plant species Cymbopogan citrates, Cinnamomum zeylanicum, Rosmarinus officinalis and Zingiber officinale against Culex tritaeniorhynchus (Cx. tritaeniorhynchus) and Anopheles subpictus (An. subpictus).MethodsEssential oils were obtained by hydro-distillation method. The mosquitoes were reared in the vector control laboratory and twenty five late third instar larvae of Cx. tritaeniorhynchus and An. subpictus were exposed to based on the wide range and narrow range test, essential oil tested at various concentrations ranging from 25 to 250 ppm. The larval mortality was observed after 24 h under the laboratory conditions. The repellent efficacy was determined against two mosquito species at three concentrations viz., 1.0, 2.5 and 5.0 mg/cm2 under laboratory conditions.ResultsResults showed all the four plant essential oil produced significant larval mortality against two mosquito species. However, the highest larvicidal activity was observed in the essential oil from Zingiber officinale against Cx. tritaeniorhynchus and An. subpictus with the LC50 and LC90 values as 98.83, 57.98 ppm and 186.55, 104.23 ppm, respectively. All the four essential oil shows significant repellency against Cx. tritaeniorhynchus than An. subpictus. Among four essential oil tested the highest repellency was observed in Zingiber officinale, a higher concentration of 5.0 mg/cm2 provided 100% protection up to 150 and180 min against Cx. tritaeniorhynchus and An. subpictus, respectively.ConclusionsIn this work, it can be concluded that four essential oils which were distilled from Cymbopogan citrates, Cinnamomum zeylanicum, Rosmarinus officinalis and Zingiber officinale showed promising larvicidal and repellent agent against Cx. tritaeniorhynchus and An. subpictus

Evaluation of Andrographis paniculata Burm.f. (Family:Acanthaceae) extracts against Culex quinquefasciatus (Say.) and Aedes aegypti (Linn.) (Diptera:Culicidae)

AbstractObjectiveTo investigate the larvicidal and ovicidal efficacy of different extracts of Andrographis paniculata (A. paniculata) against Culex quinquefasciatus (Cx. quinquefasciatus) Say and Aedes aegypti (Ae. aegypti) L. (Diptera: Culicidae).MethodsLarvicidal efficacy of the crude leaf extracts of A. paniculata with five different solvents like benzene, hexane, ethyl acetate, methanol and chloroform was tested against the early third instar larvae of Cx. quinquefasciatus and Ae. aegypti. The ovicidal activity was determined against two mosquito species to various concentrations ranging from 50-300 ppm under the laboratory conditions.ResultsThe benzene, hexane, ethyl acetate, methanol and chloroform leaf extract of A. paniculata was found to be more effective against Cx. quinquefasciatus than Ae. aegypti. The LC50 values were 112.19, 137.48, 118.67, 102.05, 91.20 ppm and 119.58, 146.34, 124.24, 110.12, 99.54 ppm respectively. Among five tested solvent, methanol and ethyl acetate crude extract was found to be most effective for ovicidal activity against two mosquito species. The extract of methanol and ethyl acetate exerted 100% mortality at 200 ppm against Cx. quinquefasciatus and at 250 ppm against Ae. aegypti.ConclusionsFrom the results it can be concluded the crude extract of A. paniculata was a potential for controlling Cx. quinquefasciatus and Ae. aegypti mosquitoes

Single-step novel biosynthesis of silver nanoparticles: a potent and eco-friendly mosquitocides

Mosquito-borne diseases like malaria, dengue, chikungunya, filariasis, and Japanese encephalitis cause thousands of deaths per year. Mosquito control is to enhance the health and quality of life of county residents and visitors through the reduction of mosquito populations. Mosquito control is of serious concern in developing countries like India due to the lack of general awareness, development of resistance, and socioeconomic reasons. Insecticides of botanical origin may serve as suitable alternative biocontrol techniques in the future. In view of the recently increased interest in developing plant origin insecticides as an alternative to chemical insecticide, In this research, we biosynthesized silver nanoparticles (Ag NP) using the Sida acuta leaf extract as reducing and stabilizing agent. The biosynthesis of Ag NP was confirmed analyzing the excitation of surface plasmon resonance using ultraviolet–visible (UV–vis) spectrophotometry. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) showed the clustered and irregular shapes of Ag NP. The presence of silver was confirmed by energy dispersive X-ray (EDX) spectroscopy. Fourier transform infrared (FTIR) spectroscopy investigated the identity of secondary metabolites, which may also act as Ag NP capping agents. The acute toxicity of S.acuta leaf extract and biosynthesized Ag NP was evaluated against larvae of Aedes aegypti, Anopheles stephensi, and Culex quinquefasciatus. Compared to the leaf aqueous extract, biosynthesized Ag NP showed higher toxicity against Ae. aegypti,                             An. stephensi, and Cx.quinquefasciatus with the LD50 values of 35.12, 39.53 and 41.44 µg/mL, respectively. This result suggests that the leaf extract have the potential to be used as an ideal eco-friendly approach for the control of vector mosquitoes

Ovicidal activity of Pithecellobium dulce (Family: Fabaceae) leaf and seed extracts against fi lariasis vector mosquito Culex quinquefasciatus (Diptera: Culicidae)

Mosquito-borne diseases with an economic impact create a loss in commercial and labor outputs, particularly incountries with tropical and subtropical climates. Mosquito control is facing a threat because of the emergence ofresistance to synthetic insecticides. Insecticides of botanical origin may serve as suitable alternative biocontroltechniques in the future. In view of recently increased interest in developing plant origin insecticides as analternative to chemical insecticide, in the present study ovicidal efficacy of different solvent leaf and seed extractof Pithecellobium dulce against filariasis vector C. quinquefasciatus. The ovicidal efficacy of the crude leaf extractsof P. dulce with five different solvents, such as benzene, hexane, ethyl acetate, methanol, and chloroform, wastested against C. quinquefasciatus. Ovicidal activity was determined against C. quinquefasciatus mosquito tovarious concentrations ranging from 100 to 600 mg/L under the laboratory conditions. Among five solvent testedthe maximum efficacy was observed in the leaf and seed methanol crude extract was found to be most effectivefor ovicidal activity against vector mosquito. The extract of methanol exerted 100% mortality at 500-600 mg/Lagainst C. quinquefasciatus. From the result, it can be concluded the crude extract of P. dulce was a potentialcandidate to develop newer and safer ovicides against C. quinquefasciatus

Commercial Mosquito Repellents and Their Safety Concerns

Mosquitoes are serious vectors of diseases threading millions of humans and animals worldwide, as malaria, filariasis, and important arboviruses like dengue, yellow fever, chikungunya, West Nile virus, and Zika viruses. The swift spread of arboviruses, parasites, and bacteria in conjunction with the development of resistance in the pathogens, parasites, and vectors represents a great challenge in modern parasitology and tropical medicine. Unfortunately, synthetic insecticides had led to some serious health and risk concerns. There are no vaccines or other specific treatments for arboviruses transmitted by mosquitoes. Accordingly, avoidance of mosquito bites remains the first line of defense. Insect repellents usually work by providing a vapor barrier deterring mosquitoes from coming into contact with the skin surface, and this chapter focused on assets and liabilities, mechanism of action, improving efficacy, safety, and future perspective of synthetic and natural repellents that could potentially prevent mosquito-host interactions, thereby playing an important role in reducing mosquito-borne diseases when used correctly and consistently

Green synthesis of silver nanoparticles using <i>Atalantia monophylla</i>: A potential eco-friendly agent for controlling blood-sucking vectors

Abstract Developing floral-based replacement molecules might manage blood-sucking vectors in an eco-friendly way. Atalantia monophylla (Am) aqueous leaf extract (ALE) and silver nanoparticles (AgNPs) were evaluated against mosquitoes (Aedes vittatus, Anopheles subpictus, and Culex vishnui) and ticks (Haemaphysalis bispinosa, Rhipicephalus microplus, and R. sanguineus) at different concentrations. Phytochemical screening and AgNPs' synthesis were performed on ALE of A. monophylla. UV-visible spectroscopy, Fourier-transform infrared (FTIR) spectroscopy, scanning electron microscope, and transmission electron microscope were used to examine the synthesized Am-AgNPs. A. monophylla's ALE included alkaloids, flavonoids, saponins, tannins, triterpenes, coumarins, anthraquinones, and phenolics. Am-AgNPs had a higher LC50 (22.19, 23.92, 26.09, 40.25, 51.87, and 60.53 μg·mL−1, respectively) than leaf aqueous extract (LAE) against Ae. vittatus, An. subpictus, Cx. vishnui, H. bispinosa, R. microplus, and R. sanguineus larvae. A. monophylla ALE and Am-AgNPs' bio-toxicity was investigated against aquatic and terrestrial non-target species (Acilius sulcatus, Anisops bouvieri, Araneus mitificus, and Cyrtophora moluccensis) with LC50 values ranging from 2,094.5 to 10,532.8 μg·mL−1, respectively. A. monophylla ALE and Am-AgNPs had little negative impacts on the chosen non-target fauna. Environmental protection is important nowadays. Green AgNPs are low-cost, readily accessible, environmentally safe, and effective pesticides. Am-AgNPs are effective alternative insecticides, requiring a considerable study on this plant to control blood-sucking vectors for worldwide human/animal health importance

Artemisia absinthium-borne compounds as novel larvicides: effectiveness against six mosquito vectors and acute toxicity on non-target aquatic organisms

The eco-friendly control of mosquito vectors is a crucial challenge of public health importance. Here we evaluated the larvicidal potential of Artemisia absinthium essential oil (EO) and its three major chemical constituents against six mosquito vectors: Anopheles stephensi, Anopheles subpictus, Aedes aegypti, Aedes albopictus, Culex quinquefasciatus, and Culex tritaeniorhynchus. The EO was obtained by leaf hydro-distillation. Its chemical composition was analyzed using gas chromatography-mass spectrometry. Major components were (E)-β-farnesene (31.6 %), (Z)-en-yn-dicycloether (11.12 %), and (Z)-β-ocimene (27.8 %). The EO was toxic effect against larval populations of An. stephensi, An. subpictus, Ae. aegypti, Ae. albopictus, Cx. quinquefasciatus, and Cx. tritaeniorhynchus, with LC50 values of 41.85, 52.02, 46.33, 57.57, 50.57, and 62.16 μg/ml. (E)-β-farnesene, (Z)-en-yn-dicycloether, and (Z)-β-ocimene were highly effective on An. stephensi (LC50 = 8.13, 16.24 and 25.84 μg/ml) followed by An. subpictus (LC50 = 10.18, 20.99, and 30.86 μg/ml), Ae. aegypti (LC50 = 8.83,17.66, and 28.35 μg/ml), Ae. albopictus (LC50 = 11.38,23.47, and 33.72 μg/ml), Cx. quinquefasciatus (LC50 = 9.66, 19.76, and 31.52 μg/ml), and Cx. tritaeniorhynchus (LC50 = 12.51,25.88, and 37.13 μg/ml). Notably, the EO and its major compounds were safer to the non-target organisms Chironomous circumdatus, Anisops bouvieri and Gambusia affinis, with LC50 values ranging from 207.22 to 4385 μg/ml. Overall, our results highlight that (E)-β-farnesene, (Z)-en-yn-dicycloether, and (Z)-β-ocimene from the A. absinthium EO represent promising eco-friendly larvicides against six key mosquito vectors with moderate toxicity against non-target organisms