Chemical composition and mosquitocidal properties of essential oil from Indian indigenous plants Ocimum tenuiflorum L. and Ocimum americanum L. against three vector mosquitoes.

Mosquitoes stand out as the most perilous and impactful vectors on a global scale, transmitting a multitude of infectious diseases to both humans and other animals. The primary objective of the current research was to assess the effectiveness of EOs from Ocimum tenuiflorum L. and Ocimum americanum L. in controlling Anopheles stephensi Liston. Culex quinquefasciatus Say and Aedes aegypti L. mosquitoes. The larvae, pupae and eggs of the mosquitoes were exposed to four different concentrations (6.25-50 ppm). The tested EOs resulted in >99-100 % mortality at 120 h for the eggs of all examined mosquito species. It also showed robust larvicidal and pupicidal activity with LC50 and LC90 values of 17-39, 23-60 ppm and 46-220, and 73-412 ppm against Aedes, Culex and Anopheles mosquito species, respectively, at 24 h of treatment. The Suitability Index or Predator Safety Factor demonstrated that the EOs extracted from O. tenuiflorum L. and O. americanum L. did not cause harm to P. reticulata, D. indicus (water bug), G. affinis and nymph (dragonfly). GC-MS analysis identified the major probable constituents of the oil, including Phenol, 2-Methoxy-4-(1-Propenyl)- (28.29 %); 1-Methyl-3-(1'-Methylcyclopropyl) Cyclopentene (46.46 %); (E,E,E)-3,7,11,15-Tetramethylhexadeca-1,3,6,10,14-Pentaene (18.91 %) and 1,3-Isobenzofurandione, 3a,4,7,7a-Tetrahydro-4,7-Dimethyl (33.02 %). These constituents may play a significant role in the mosquitocidal activity of the oil. The same results were identified in the formulation prepared from the EOs. This marks the first report confirming the successful utilization of EOs derived from O. tenuiflorum L. and O. americanum L. in mosquito population control initiatives.

Exploring the bioactive potential leaves of Sphaeranthus indicus: Targeting immature stages of Aedes aegypti and Culex quinquefasciatus mosquito vectors through bioassay-guided screening and fraction isolation.

Mosquito control is vital for combating mosquito-borne diseases, but concerns exist regarding the use of synthetic insecticides. This study aimed to explore eco-friendly alternatives derived from natural sources. The larvicidal, pupicidal, and ovicidal activities of various fractions obtained from the hexane leaf extract of Sphaeranthus indicus were investigated against two important mosquito vectors, Aedes aegypti and Culex quinquefasciatus. S. indicus leaves were extracted with hexane and column chromatography was performed with hexane, ethyl acetate, methanol, and their mixtures as eluents. Among the ten fractions (F1-F10) evaluated, fraction 'F-4' exhibited significant activity against third instar larvae, pupae, and eggs of both mosquito species, closely followed by 'F-5' . At a concentration of 10 ppm, 'F-4' achieved 100% mortality in larvae and displayed LC50 values of 5.08 ppm and 5.03 ppm for Ae. aegypti and Cx. quinquefasciatus larvae, respectively. The LC50 values for pupae were 6.12 ppm and 5.83 ppm for Ae. aegypti and Cx. quinquefasciatus, respectively. Regarding ovicidal activity, 'F-4' demonstrated percentages ranging from 63.2% to 64.8% against Ae. aegypti and Cx. quinquefasciatus eggs, respectively. These findings underscore the potent larvicidal, pupicidal, and ovicidal effects of fraction 'F-4' from S. indicus against the targeted mosquito species. Further research is warranted to identify the active compounds responsible for these effects and explore practical applications for sustainable mosquito control strategies.

Mosquito larvicidal, pupicidal and ovicidal effects of the extracts of Peltophorum pterocarpum flowers on Aedes aegypti and Culex quinquefasciatus.

Mosquitoes are the vectors of several diseases like dengue, chikungunya, malaria etc. The three important mosquito species in India are Aedes aegypti, Culex quinquefasciatus and Anopheles stephensi. Several plant extracts have been tested for their anti-mosquito activity. In this dissertation, the larvicidal, pupicidal and ovicidal activities of the successive hexane, chloroform and methanol extracts of Peltophorum pterocarpum (Fabaceae) on mosquitoes are reported. The larvicidal activity of those extracts on both Aedes aegypti and Culex quinquefasciatus mosquitoes was found to be in a decreasing order of hexane, methanol and chloroform - the LC50 values for these extracts were 111.81 and 104.84 ppm, 121.92 and 121.56 ppm, 357.2 and 352.0 ppm respectively. Their pupicidal activity on both mosquitoes was found in the order of methanol, chloroform and hexane - the LC50 values for these extracts being 172.8 and 162.35 ppm, 425.8 respectively. Their ovicidal activity on both mosquitoes was found to be very low, even at the higher concentration of 500 ppm. This is the first report on the effect of the extracts of Peltophorum pterocarpum flowers on the two mosquito species of Aedes aegypti, Culex quinquefasciatus. In the present work, the results showed that the hexane extract had the highest larvicidal activity, while methanol showed the highest pupicidal activity besides larvicidal activity. Hence, the methanol extract holds promise to be used as mosquitocidal agent against the above two vectors.

Modulation of the Morphological Architecture of Mn2O3 Nanoparticles to MnCoO Nanoflakes by Loading Co3+ Via a Co-Precipitation Approach for Mosquitocidal Development.

The spread of many infectious diseases by vectors is a globally severe issue. Climate change and the increase of vector resistance are the primary sources of rising mosquito populations. Therefore, advanced approaches are needed to prevent the dispersal of life-threatening diseases. Herein, Mn2O3 NPs and MnCoO nanocomposites were presented as mosquitocidal agents. The synthesized samples were prepared by a co-precipitation route and characterized using different techniques indicating the change of host Mn2O3 structure to 2D MnCoO nanoflakes with Co3+ integration. The thermal decomposition of the nanoparticles was examined by TGA analysis, showing high stability. The energy gap (Eg) of Mn2O3 was estimated within the visible spectrum of the value 2.95 eV, which reduced to 2.80 eV with doping support. The impact of Mn2O3 and MnCoO on immature stages was investigated by semithin photomicrographs exhibiting significant changes in the midgut, fat tissue and muscles of the third larval instar. Moreover, the external deformations in pupae were examined using scanning electron microscopy (SEM).

Bioactive Molecules Derived from Plants in Managing Dengue Vector Aedes aegypti (Linn.).

Mosquitoes are the potential vectors of several viral diseases such as filariasis, malaria, dengue, yellow fever, Zika fever and encephalitis in humans as well as other species. Dengue, the most common mosquito-borne disease in humans caused by the dengue virus is transmitted by the vector Ae. aegypti. Fever, chills, nausea and neurological disorders are the frequent symptoms of Zika and dengue. Thanks to various anthropogenic activities such as deforestation, industrialized farming and poor drainage facilities there has been a significant rise in mosquitoes and vector-borne diseases. Control measures such as the destruction of mosquito breeding places, a reduction in global warming, as well as the use of natural and chemical repellents, mainly DEET, picaridin, temephos and IR-3535 have proven to be effective in many instances. Although potent, these chemicals cause swelling, rashes, and eye irritation in adults and children, and are also toxic to the skin and nervous system. Due to their shorter protection period and harmful nature towards non-target organisms, the use of chemical repellents is greatly reduced, and more research and development is taking place in the field of plant-derived repellents, which are found to be selective, biodegradable and harmless to non-target species. Many tribal and rural communities across the world have been using plant-based extracts since ancient times for various traditional and medical purposes, and to ward off mosquitoes and various other insects. In this regard, new species of plants are being identified through ethnobotanical surveys and tested for their repellency against Ae. aegypti. This review aims to provide insight into many such plant extracts, essential oils and their metabolites, which have been tested for their mosquitocidal activity against different life cycle forms of Ae. Aegypti, as well as for their efficacy in controlling mosquitoes.

Larvicidal and pupicidal activity of phyto-synthesized zinc oxide nanoparticles against dengue vector aedes aegypti.

This study aimed to assess the phyto-synthesizing potential of Tarenna asiatica methanol leaf extract as well as its larvicidal and pupicidal potential against Aedes aegypti larvae. According to the findings of this study, the methanol leaf extract of T. asiatica has the potential to synthesize zinc oxide nanoparticles from zinc acetate dehydrate. Standard analytical techniques such as UV-visible spectrophotometer, Fourier-transform infrared spectroscopy, X-ray Diffraction analysis, Scanning Electron Microscope, and Energy Dispersive X-Ray were used to characterize the phyto-synthesized nanoparticles. The zinc oxide nanoparticles synthesized ranged in size from 22.35 to 31.27 nm and was spherical in shape. These nanoparticles demonstrated excellent larvicidal activity against Aedes aegypti larvae in the second, third, and fourth in stars, as well as significant pupicidal activity. These findings suggest that the methanol leaf extract of T. asiatica synthesized zinc oxide nanoparticles, which could be used to develop mosquito repellents.

Mosquitocidal activities of Chenopodium botrys whole plant n-hexane extract against Culex quinquefasciatus / Atividades mosquitocidas do extrato de n-hexano de planta inteira de Chenopodium botrys contra Culex quinquefasciatus

This research aimed to investigate various mosquitocidal activities of Chenopodium botrys whole- plant n-hexane extract against Culex quinquefasciatus. The extract showed remarkable larvicidal, pupicidal, adulticidal, oviposition deterrent and adult emergence inhibitory activities against Cx. quinquefasciatus. During the larvicidal and pupicidal activities, the 24-hour lethal concentration (LC50) of extract against 2nd instar larvae, 4th instar larvae and pupae were 324.6, 495.6 and 950.8 ppm, respectively. During the CDC (Centers for Disease Control and Prevention) bottle bioassay for adulticidal activity, the median knockdown times (KDT50) at 1.25% concentration was 123.4 minutes. During the filter paper impregnation bioassay for adulticidal activity, the KDT50 value at 0.138 mg/cm2 concentration was 48.6 minutes. The extract was fractionated into 14 fractions through silica gel column chromatography which were then combined into six fractions on the basis of similar retention factor (Rf) value. These fractions were screened for adulticidal activity by applying CDC bottle bioassay. The fraction obtained through 60:40 to 50:50% n-hexanes-chloroform mobile phase with 0.5 Rf value showed 100% adulticidal activity at 0.2% concentration. During oviposition deterrent activity, the highest concentration (1000 ppm) showed 71.3 ± 4.4% effective repellence and 0.6 ± 0.1 oviposition activity index. During adult emergence inhibition activity, the median emergence inhibition (EI50) value was 312.3 ppm. From the outcome of the present investigation, it is concluded that the n-hexane extract of C. botrys whole- plant possesses strong larvicidal, pupicidal, adulticidal, oviposition deterrent and adult emergence inhibitory activities against Cx. quinquefasciatus.

Esta pesquisa teve como objetivo investigar várias atividades mosquitocidas do extrato n-hexano de planta inteira de Chenopodium botrys contra Culex quinquefasciatus. O extrato mostrou atividades larvicida, pupicida, adulticida, dissuasora de oviposição e inibidora da emergência de adultos contra a Cx. quinquefasciatus. Durante as atividades larvicida e pupicida, a concentração letal de 24 horas (CL50) do extrato contra larvas de 2º estádio, larvas de 4º estádio e pupa foi de 324,6, 495,6 e 950,8 ppm, respectivamente. Durante o bioensaio com frasco do CDC (Centros para Controle e Prevenção de Doenças) para adulticida, o tempo médio de desativação (KDT50) na concentração de 1,25% foi de 123,4 minutos. Durante o bioensaio de impregnação com papel de filtro para a atividade adulticida do extrato, o valor KDT50 na concentração de 0,138 mg / cm2 foi de 48,6 minutos. O extrato foi fracionado em 14 frações através de cromatografia em coluna de gel de sílica que foram então combinadas em seis frações com base em um valor de fator de retenção (Rf) semelhante. Essas frações foram selecionadas quanto à atividade adulticida por meio da aplicação do bioensaio com garrafa do CDC. A fração obtida através da fase móvel de n-hexanos-clorofórmio 60:40% a 50:50% com valor de 0,5 Rf apresentou atividade adulticida de 100% na concentração de 0,2%. Durante a atividade de dissuasão da oviposição, a maior concentração de extrato (1000 ppm) apresentou repelência efetiva de 71,3 ± 4,4% e índice de atividade de oviposição de 0,6 ± 0,1. Durante a atividade de inibição da emergência de adultos, o valor médio de inibição da emergência (EI50) foi de 312,3 ppm. A partir do resultado da presente investigação, conclui-se que o extrato de n-hexano da planta inteira de C. botrys possui fortes atividades larvicida, pupicida, adulticida, dissuasora da oviposição e inibidora da emergência de adultos contra a Cx. quinquefasciatus.

Mosquitocidal activities of Chenopodium botrys whole plant n-hexane extract against Culex quinquefasciatus

Abstract This research aimed to investigate various mosquitocidal activities of Chenopodium botrys whole- plant n-hexane extract against Culex quinquefasciatus. The extract showed remarkable larvicidal, pupicidal, adulticidal, oviposition deterrent and adult emergence inhibitory activities against Cx. quinquefasciatus. During the larvicidal and pupicidal activities, the 24-hour lethal concentration (LC50) of extract against 2nd instar larvae, 4th instar larvae and pupae were 324.6, 495.6 and 950.8 ppm, respectively. During the CDC (Centers for Disease Control and Prevention) bottle bioassay for adulticidal activity, the median knockdown times (KDT50) at 1.25% concentration was 123.4 minutes. During the filter paper impregnation bioassay for adulticidal activity, the KDT50 value at 0.138 mg/cm2 concentration was 48.6 minutes. The extract was fractionated into 14 fractions through silica gel column chromatography which were then combined into six fractions on the basis of similar retention factor (Rf) value. These fractions were screened for adulticidal activity by applying CDC bottle bioassay. The fraction obtained through 60:40 to 50:50% n-hexanes-chloroform mobile phase with 0.5 Rf value showed 100% adulticidal activity at 0.2% concentration. During oviposition deterrent activity, the highest concentration (1000 ppm) showed 71.3 ± 4.4% effective repellence and 0.6 ± 0.1 oviposition activity index. During adult emergence inhibition activity, the median emergence inhibition (EI50) value was 312.3 ppm. From the outcome of the present investigation, it is concluded that the n-hexane extract of C. botrys whole- plant possesses strong larvicidal, pupicidal, adulticidal, oviposition deterrent and adult emergence inhibitory activities against Cx. quinquefasciatus.

Resumo Esta pesquisa teve como objetivo investigar várias atividades mosquitocidas do extrato n-hexano de planta inteira de Chenopodium botrys contra Culex quinquefasciatus. O extrato mostrou atividades larvicida, pupicida, adulticida, dissuasora de oviposição e inibidora da emergência de adultos contra a Cx. quinquefasciatus. Durante as atividades larvicida e pupicida, a concentração letal de 24 horas (CL50) do extrato contra larvas de 2º estádio, larvas de 4º estádio e pupa foi de 324,6, 495,6 e 950,8 ppm, respectivamente. Durante o bioensaio com frasco do CDC (Centros para Controle e Prevenção de Doenças) para adulticida, o tempo médio de desativação (KDT50) na concentração de 1,25% foi de 123,4 minutos. Durante o bioensaio de impregnação com papel de filtro para a atividade adulticida do extrato, o valor KDT50 na concentração de 0,138 mg / cm2 foi de 48,6 minutos. O extrato foi fracionado em 14 frações através de cromatografia em coluna de gel de sílica que foram então combinadas em seis frações com base em um valor de fator de retenção (Rf) semelhante. Essas frações foram selecionadas quanto à atividade adulticida por meio da aplicação do bioensaio com garrafa do CDC. A fração obtida através da fase móvel de n-hexanos-clorofórmio 60:40% a 50:50% com valor de 0,5 Rf apresentou atividade adulticida de 100% na concentração de 0,2%. Durante a atividade de dissuasão da oviposição, a maior concentração de extrato (1000 ppm) apresentou repelência efetiva de 71,3 ± 4,4% e índice de atividade de oviposição de 0,6 ± 0,1. Durante a atividade de inibição da emergência de adultos, o valor médio de inibição da emergência (EI50) foi de 312,3 ppm. A partir do resultado da presente investigação, conclui-se que o extrato de n-hexano da planta inteira de C. botrys possui fortes atividades larvicida, pupicida, adulticida, dissuasora da oviposição e inibidora da emergência de adultos contra a Cx. quinquefasciatus.

Mosquitocidal activities of Chenopodium botrys whole plant n-hexane extract against Culex quinquefasciatus / Atividades mosquitocidas do extrato de n-hexano de planta inteira de Chenopodium botrys contra Culex quinquefasciatus

Abstract This research aimed to investigate various mosquitocidal activities of Chenopodium botrys whole- plant n-hexane extract against Culex quinquefasciatus. The extract showed remarkable larvicidal, pupicidal, adulticidal, oviposition deterrent and adult emergence inhibitory activities against Cx. quinquefasciatus. During the larvicidal and pupicidal activities, the 24-hour lethal concentration (LC50) of extract against 2nd instar larvae, 4th instar larvae and pupae were 324.6, 495.6 and 950.8 ppm, respectively. During the CDC (Centers for Disease Control and Prevention) bottle bioassay for adulticidal activity, the median knockdown times (KDT50) at 1.25% concentration was 123.4 minutes. During the filter paper impregnation bioassay for adulticidal activity, the KDT50 value at 0.138 mg/cm2 concentration was 48.6 minutes. The extract was fractionated into 14 fractions through silica gel column chromatography which were then combined into six fractions on the basis of similar retention factor (Rf) value. These fractions were screened for adulticidal activity by applying CDC bottle bioassay. The fraction obtained through 60:40 to 50:50% n-hexanes-chloroform mobile phase with 0.5 Rf value showed 100% adulticidal activity at 0.2% concentration. During oviposition deterrent activity, the highest concentration (1000 ppm) showed 71.3 ± 4.4% effective repellence and 0.6 ± 0.1 oviposition activity index. During adult emergence inhibition activity, the median emergence inhibition (EI50) value was 312.3 ppm. From the outcome of the present investigation, it is concluded that the n-hexane extract of C. botrys whole- plant possesses strong larvicidal, pupicidal, adulticidal, oviposition deterrent and adult emergence inhibitory activities against Cx. quinquefasciatus.

Resumo Esta pesquisa teve como objetivo investigar várias atividades mosquitocidas do extrato n-hexano de planta inteira de Chenopodium botrys contra Culex quinquefasciatus. O extrato mostrou atividades larvicida, pupicida, adulticida, dissuasora de oviposição e inibidora da emergência de adultos contra a Cx. quinquefasciatus. Durante as atividades larvicida e pupicida, a concentração letal de 24 horas (CL50) do extrato contra larvas de 2º estádio, larvas de 4º estádio e pupa foi de 324,6, 495,6 e 950,8 ppm, respectivamente. Durante o bioensaio com frasco do CDC (Centros para Controle e Prevenção de Doenças) para adulticida, o tempo médio de desativação (KDT50) na concentração de 1,25% foi de 123,4 minutos. Durante o bioensaio de impregnação com papel de filtro para a atividade adulticida do extrato, o valor KDT50 na concentração de 0,138 mg / cm2 foi de 48,6 minutos. O extrato foi fracionado em 14 frações através de cromatografia em coluna de gel de sílica que foram então combinadas em seis frações com base em um valor de fator de retenção (Rf) semelhante. Essas frações foram selecionadas quanto à atividade adulticida por meio da aplicação do bioensaio com garrafa do CDC. A fração obtida através da fase móvel de n-hexanos-clorofórmio 60:40% a 50:50% com valor de 0,5 Rf apresentou atividade adulticida de 100% na concentração de 0,2%. Durante a atividade de dissuasão da oviposição, a maior concentração de extrato (1000 ppm) apresentou repelência efetiva de 71,3 ± 4,4% e índice de atividade de oviposição de 0,6 ± 0,1. Durante a atividade de inibição da emergência de adultos, o valor médio de inibição da emergência (EI50) foi de 312,3 ppm. A partir do resultado da presente investigação, conclui-se que o extrato de n-hexano da planta inteira de C. botrys possui fortes atividades larvicida, pupicida, adulticida, dissuasora da oviposição e inibidora da emergência de adultos contra a Cx. quinquefasciatus.

Sustainable development through the bio-fabrication of ecofriendly ZnO nanoparticles and its approaches to toxicology and environmental protection.

Mosquito control is becoming more difficult as a result of the rise in resistance to toxic chemical insecticides. The insecticides of bio-fabrication sources may serve as a convenient alternative to environmentally acceptable methods in the future. The larvicidal and pupicidal activities of bio-fabricated zinc oxide nanoparticles (ZnO NPs) on the different instar larvae and pupae of Anopheles subpictus Grassi (Malaria vector) and Culex quinquefasciatus Say (lymphatic filariasis) were investigated in this study. The results recorded from XRD, FTIR, SEM-EDX, and TEM analyses confirmed the bio-fabrication of ZnO NPs. Such nanoparticles were nearly spherical and agglomerated with a size of 34.21 nm. GC-MS analysis of methanol extract revealed the compound, stigmasterol (C29H48O) as major one. Mosquito larvae and pupae of targeted mosquito were tested against varied concentrations of the bio-fabricated ZnO NPs and methanol extract of Vitex negundo for 24 h. The maximum activity was recorded from ZnO NPs against the larvae and pupae of A. subpictus LC50 which were 1.70 (I), 1.66 (II), 1.93 (III), 2.48 (IV), and 3.63 mg/L (pupa) and C. quinquefasciatus LC50 were 1.95 (I), 2.63 (II), 2.90 (III), 4.32 (IV), and 4.61 mg/L (pupa) respectively. ZnO NPs exhibited strong DPPH radical and FRAP scavengers compared to the aqueous extract of V. negundo. Also, V. negundo leaf methanol extract (VNLME) and ZnO NPs were evaluated for their cytotoxicity on HeLa cells, which exhibited the IC50 values of 72.35 and 43.70µg/mL, respectively. The methylene blue (MB) dye, which is harmful to both aquatic and terrestrial life, was degraded using the biosynthesized ZnO nanoparticles. At 664 nm, 81.2% of the MB dye had degraded after 120 min of exposure to sunlight. Overall, our results revealed that ZnO NPs are the perfect biological agent and economical for the control of malaria, filariasis vectors, antioxidant, HeLa cells, and MB blue dye degradation under sunlight irradiation.

Combinations of plant essential oils and their major compositions inducing mortality and morphological abnormality of Aedes aegypti and Aedes albopictus.

Extensive uses of synthetic insecticides to control mosquito's populations have induced the insects to develop resistance against them, rendering them ineffective today. Moreover, they cause serious impacts on human health and the ecosystem. Therefore, safe and effective natural alternatives are needed. This study evaluated the larvicidal and pupicidal activities of essential oils (EOs) from Illicium verum and Zanthoxylum limonella and the major constituents against Aedes aegypti and Aedes albopictus mosquitoes as well as recorded their morphological aberrations at death. The GC-MS analysis showed that trans-anethole was the major constituent of I. verum EO, and limonene was the major constituent of Z. limonella EO. Both were more effective against the larvae and pupae of Ae. aegypti than those of Ae. albopictus. A 2.5% I. verum EO + 2.5% trans-anethole combination showed the highest larvicidal and pupicidal effects against Ae. aegypti and Ae. albopictus with an LT50 ranging from 0.2-6.9 h. Between the two tested constituents, trans-anethole exhibited stronger larvicidal and pupicidal activities (LC50 ranging 2.4-3.4%) against the two tested mosquito species than d-limonene (LC50 ranging 2.5-3.7%). Most importantly, 5% trans-anethole, 5% d-limonene, and 2.5% I. verum EO + 2.5% trans-anethole were more effective (LT50 ranging 0.1-0.3 h) than 1% (w/w) temephos (LT50 ranging 2.9-3.1 h). Morphological aberrations at death observed were such as color pigment and thorax shape abnormalities. To conclude, trans-anethole, d-limonene, and a combination of I. verum EO + trans-anethole, are natural compounds that not only are as effective as temephos at the time of this study, but should be also be much safer to human health.

Bio-efficacy of Soil Actinomycetes and an Isolated Molecule 1,2-Benzenedicarboxylic Acid from Nonomuraea sp. Against Culex quinquefasciatus Say and Aedes aegypti L. Mosquitoes (Diptera: Culicidae).

Vector-borne diseases such as filariasis and dengue that contribute significantly to disease burden, death, poverty, and social frailty are still a major public healthcare problem worldwide. Currently, synthetic chemicals have been used in mosquito control programs. However, repeated use of chemical insecticides causes environmental pollution and harmful effects on non-target organisms. Therefore, alternative ecofriendly sources from biological source are urgently needed to manage mosquitoes. In this respect, the present study was aimed to evaluate mosquito larvicidal and pupicidal activities of 22 crude extracts of soil actinomycetes on Culex quinquefasciatus and Aedes aegypti and to identify the active molecule. Briefly, the crude ethyl acetate extract and fractions were tested at 62.5, 125, 250, and 500 ppm and 2.5, 5.0, 7.5, and 10.0 ppm concentrations on larval and pupal stages of Cx. quinquefasciatus and Ae. aegypti. The larval and pupal mortality was assessed after 24 h of treatment. Among the 22 isolates screened, Nonomuraea sp. VAS-16 exhibited significant larvicidal and pupicidal activities against the tested mosquito species. Among the 18 fractions screened, fraction-6 showed strong larvicidal and pupicidal activities with the LC50 and LC90 values of 9.1, 18.7, 9.82, and 22.85 ppm against the larvae and LC50 and LC90 values of 10.5, 23.1, 12.3, and 24.13 ppm against the pupae of Cx. quinquefasciatus and Ae. aegypti, respectively. Fascinatingly, the isolated compound 1,2-benzenedicarboxylic acid from fraction-6 at 0.5, 1.0, 1.5, and 2.0 ppm concentration recorded lower LC50 and LC90 values of 4.27, 14.90, 4.67, and 11.90 ppm against the larvae and LC50 and LC90 values of 4.58, 12.06, 5.36, and 13.07 ppm against the pupae of Cx. quinquefasciatus and Ae. aegypti, respectively. On the other hand, the compound recorded less ovicidal activity of 11.0% and 10.3% at 2 ppm against the eggs of Cx. quinquefasciatus and Ae. aegypti, respectively. The present study clearly shows that the crude extract and the compound from Nonomuraea sp. VAS-16 can be used as an effective biopesticide in integrated mosquito management program.

Molecular characterization, gas chromatography mass spectrometry analysis, phytochemical screening and insecticidal activities of ethanol extract of Lentinus squarrosulus against Aedes aegypti (Linnaeus).

Mosquito-transmitted diseases like zika, dengue, chikungunya, and yellow fever are known to affect human health worldwide. Numerous synthetic insecticides have been used as vector control for these diseases, but there is the challenge of environmental toxicity and vector resistance. This study investigated the medicinal and insecticidal potential of Lentinus squarrosulus against Aedes aegypti. The fruiting bodies were identified morphologically as well as using internal transcribed spacer (ITS) sequences for its molecular characterization. Genomic deoxyribonucleic acid (DNA) yield was confirmed with NanoDrop Spectrophotometer ND-1000 and amplified with ITSl and ITS4 primers. The amplicons were sequenced and the National Center for Biotechnology Information (NCBI) database identified the nucleotides. Its ethanol extract was subjected to phytochemical screening and gas chromatography mass spectrometry (GC-MS) analysis and tested against the pupa and fourth instar larva of Aedes aegypti with percentage mortality monitored. The Macrofungus was identified morphologically and confirmed with molecular characterization as Lentinus squarrosulus (LS). The gene sequence was deposited in GenBank (Accession number MK629662.1). GC-MS analysis showed that its ethanol extract has 25 bioactive compounds with 9,12-Octadecadienoic acid, ethyl ester having the highest percentage of 43.32% as well as methyl-2-oxo-1-pyrrolidine acetate and 17-octadecynoic acid having the lowest percentage (0.09%). The macrofungus contained varied concentrations of phytochemicals including phenols (159 mg/g GAE), tannins (1.6 mg/g TAE), and flavonoids (31.4 mg/g QE). The ethanol extract had significant potent effects on Aedes aegypti larva and pupa which could be due to the occurrence and abundance of 9,12-octadecadienoic acid in LS. The LC50 of the extract for larvicidal and pupicidal activities were 2.95 mg/mL and 3.55 mg/mL, respectively, while its LC90 were 6.31 mg/mL and 5.75 mg/mL respectively. Lentinus squarrosulus had insecticidal effects against the Aedes aegypti larva and pupa and possessed great potential as a source of alternative medicine and eco-friendly insecticides.

Toxicity of the essential oil from Thymus serpyllum and thymol to larvae and pupae of the housefly Musca domestica L. (Diptera: Muscidae).

The essential oil (EO) of Thymus serpyllum and thymol were evaluated for their insecticidal activity against the housefly (Musca domestica) larvae and pupae. Contact toxicity and fumigation bioassays were used. Chemical composition analysis of T. serpyllum EO by gas chromatographic mass spectrometry (GC-MS) revealed that thymol (41.6%), p-cymene (21.9%), and γ-terpinene (19.2%) were the major components. For larval assays, the LC50 value of T. serpyllum EO was 0.4 µl/cm2 for contact toxicity and 20.9 µl/l for fumigation toxicity. For thymol, the contact toxicity LC50 value was 0.035 µl/cm2 and the fumigation LC50 value was 2.0 µl/l. For the pupal assay, T. serpyllum EO had a percentage inhibition rate (PIR) value of 100% for both contact toxicity (1.0 µl/cm2) and fumigation toxicity assay (25 µl/l), whereas thymol had a PIR of 100% for contact toxicity (0.1 µl/cm2) and fumigation assay (5 µl/l). This study shows that T. serpyllum EO and thymol are toxic to housefly larvae and pupae and have the potential for use in the population control of this species.

Efecto tóxico de los extractos de semillas de Annona muricata potenciados con dimetilsulfóxido sobre larvas IV y pupas de Aedes aegypti / Toxic effect of Annona muricata seed extracts potentiated with dimethyl sulfoxide on IV larvae and pupae of Aedes aegypti

Resumen El objetivo de este estudio fue demostrar que los principios activos de las semillas de Annona muricata combinados con el extracto etanólico y dimetilsulfóxido (EE-DMSO), incrementan la mortalidad de larvas IV y pupas de Aedes aegypti con relación a extractos acuosos (EA) y extractos etanólicos (EE). Las bioactividades se calcularon por comparación de los porcentajes de mortalidad a las 6, 12, 24 y 48 horas in vitro y campo simulado. Los resultados indicaron mortalidad progresiva dependiente de las concentraciones y tiempos de exposición en larvas y reacción knock-down en pupas. In vitro a 5 mg.L-1, EA y EE ejercieron 100% de mortalidad larvaria en 24 horas de exposición (CL50=46.16 y 19.28 mg.L-1 respectivamente), en contraste con EE-DMSO, que inició sobre 62% con 0.5 mg.L-1 a las 6 horas (CL50=20.33 mg.L-1). La acción pupicida de EA y EE reveló 100% de mortalidad desde 24 horas en todas las concentraciones, a diferencia de EE-DMSO que se alcanzó entre 6 y 12 horas. En campo simulado, EA y EE ejercieron 100% de mortalidad a las 24 horas en larvas (16.91 y 21.21 mg.L-1 ), mientras que en pupas (20.44 y 23.03 mg.L-1) ocurrió a las 12 horas, entretanto, la actividad pupicida de EE-DMSO fue 100% en 6 horas. Los efectos comparativos in vitro y campo simulado denotaron patrones similares de respuestas larvicida y pupicida, pero con mayor sensibilidad en pupas. Los principios activos de las semillas de A. muricata combinados con EE-DMSO potencian la respuesta mortal de larvas y pupas de A. aegypti in vitro y campo simulado.

Abstract The objective of this study was to demonstrate that active ingredients of Annona muricata seeds can be enhanced as a result of mixture of both ethanolic extract of A. muricata seeds and Dimethylsulfoxide (EE-DMSO). Percentage mortalities at 6, 12, 24 and 48 hours on fourth instar larvae and pupae of Aedes aegypti were calculated in order to compare bioactivities of aqueous (AE), ethanolic extracts (EE) and EE-DMSO under laboratory and simulated field conditions. Results showed larval mortality concentration- and time-dependent, and knock-down responses in pupae. In laboratory, AE and EE exerted 100% larval mortality at 5 mg.L-1 after 24 hours (LC50= 46.16 and 19.28 mg.L-1). Conversely, EE-DMSO showed between 62 - 100% mortality at 0.5 mg.L-1 for over 6 hours (LC50= 20.33 mg.L-1). Pupicidal effects in AE and EE revealed 100% mortality at 24 hours employing all concentrations, except in EE-DMSO which commenced when individuals were exposed between 6 and 12 hours. In simulated field, AE and EE provoked 100% larval mortality at 24 hours (16.91 y 21.21 mg.L-1) while pupal mortality at 12 hours (20.44 y 23.03 mg.L-1). Percentage mortality of pupae was 100% using EE-DMSO even before 6 hours. Comparative toxic effects of laboratory and simulated-field systems have shown to maintain a similar pattern of larval mortality and more sensitive responses in pupae. Accordingly, larval and pupal mortality responses of A. aegypti were enhanced with the use of EE-DMSO and active ingredients of A. muricata seeds under laboratory and simulated field conditions.

Utilizing larvicidal and pupicidal efficacy of Eucalyptus and neem oil against Aedes mosquito: An approach for mosquito control.

BACKGROUND AND OBJECTIVES: Plant-based products can provide safe and biodegradable mosquito control agents. The essential oils have a strong odor due to complex secondary metabolites and exhibit lower density than that of water, which renders them suitable to form a thin layer above the water surface. The present study was designed to evaluate the larvicidal, pupicidal activity of Eucalyptus and neem oils against Aedes aegypti and Aedes albopictus. MATERIALS AND METHODS: We evaluated the activity of commercially available Eucalyptus (Eucalyptus globulus) and neem (Azadirachta indica) oils against larvae and pupae of A. aegypti and A. albopictus for their larvicidal and pupicidal activity, stability in different water types, dependence on volume and surface area of the water body, and residual efficacy. RESULTS: Eucalyptus oil was found to be more effective against larvae and pupae at lower concentrations, i.e., concentration at which 50% is observed (LC50) for larvae and pupae was 93.3 and 144.5 parts per million (ppm) and concentration at which 90% is observed (LC90) was 707.9 and 741.3 ppm, respectively, while for neem oil, LC50 for larvae and pupae was 7852 and 19,054 ppm and LC90 was 10,092 and 19,952 ppm, respectively. The efficacy of Eucalyptus oil depended on surface area rather than volume of water, and the residual efficacy of Eucalyptus oil was up to 8 days. CONCLUSIONS: Eucalyptus oil was more effective against mosquito larvae at lower concentration as compared to neem oil. It can, therefore, be utilized in the community in artificial and small temporary water bodies as an eco-friendly vector control measure in the era of increasing resistance to chemical insecticides.

Enhanced mosquitocidal efficacy of colloidal dispersion of pyrethroid nanometric emulsion with benignity towards non-target species.

The rising threat of vector-borne diseases and environmental pollution has instigated the investigation of nanotechnology-based applications. The current study deals with a nanotechnological application involving the usage of nanometric pesticides such as permethrin nanoemulsion. The mean droplet diameter and zeta potential of the prepared permethrin nanoemulsion were found to be 12.4 ±â€¯1.13 nm and -20.4 ±â€¯0.56 mV, respectively. The temporal stability of permethrin nanoemulsion was found to be 4 days when checked in the external environment. The permethrin nanoemulsion exhibited LC50 values of 0.038 and 0.047 mgL-1 and 0.049 and 0.063 mgL-1 against larval and pupal stages of Culex tritaeniorhynchus and Aedes aegypti, respectively. The results obtained from the larvicidal and pupicidal assay were corroborated with the histopathological and biochemical profiles of hosts upon treatment with nanometric pesticide. Further, the biosafety studies of the nanopesticide were carried out against different non-target species like freshwater algae (Closterium), Cicer arietinum (Chickpea) and Danio rerio (Zebrafish), and the mosquitocidal concentration of nanopesticide was found to be non-toxic. The following study, therefore, describes the mosquitocidal efficacy of nanometric pesticide formulated in a greener approach, which can become a substitute for conventional pesticide application in an eco-benign manner.

Insecticidal and Repellent Activity of Several Plant-Derived Essential Oils Against Aedes aegypti.

We examined the pupicidal, adulticidal, repellent, and oviposition-deterrent activities of essential oils (EOs) from Lippia alba, L. origanoides, Eucalyptus citriodora, Cymbopogon citratus, Cymbopogon flexuosus, Citrus sinensis , Cananga odorata , Swinglea glutinosa, and Tagetes lucida plants against Aedes aegypti under laboratory conditions. Pupicidal and adulticidal activities were assessed at exploratory concentrations of 250, 310, and 390 parts per million (ppm); and 30, 300, and 1,000 ppm, respectively. The greatest pupicidal activity was exhibited at 390 ppm with a 24-h exposure by L. origanoides, and 390 ppm with a 48-h exposure by Citrus sinensis . Lippia origanoides killed all adult mosquitoes at 300 ppm after 120 min of exposure. Only L. origanoides and E. citriodora EOs, applied at 1,000 ppm to human skin, produced the greatest repellency (100%) to host-seeking Ae. aegypti after 2 min of exposure; the repellency decreased between 12% and 10% after 15 min. Complete oviposition deterrence by gravid Ae. aegypti was observed for E. citriodora EOs at 200 ppm with an oviposition activity index of -1.00. These results confirm that the EOs assessed in this study have insecticidal, repellent, and oviposition-deterrent activities against the dengue vector, Ae. aegypti.

Laboratory Evaluations of the Fractions Efficacy of Annona senegalensis (Annonaceae) Leaf Extract on Immature Stage Development of Malarial and Filarial Mosquito Vectors.

BACKGROUND: Within the framework to control mosquitoes, ovicidal, larvicidal and pupicidal activity of Annona senegalensis leaf extract and its 4 fractions against Anopheles gambiae and Culex quinquefasciatus were evaluated in the laboratory conditions. METHODS: Ovicidal test was performed by submitting at least 100 eggs of mosquitoes to 125, 250, 500, 1000 and 2000 ppm concentrations, while larvicidal and pupicidal effects were assessed by submitting 25 larvae or pupae to the concentrations of 2500, 1250, 625 and 312.5 ppm of plant extract or fractions of A. senegalensis. RESULTS: The eggs of An. gambiae were most affected by N-hexane (0.00% hatchability) and chloroform (03.67% hatchability) fractions compared to Cx. quinquefasciatus where at least 25 % hatchability were recorded at 2000 ppm. For larvicidal test, N-hexane (LC50= 298.8 ppm) and chloroform (LC50= 418.3 ppm) fractions were more effective than other fractions on An. gambiae larvae while, a moderate effectiveness was also observed with N-hexane (LC50= 2087.6 ppm), chloroform (LC50= 9010.1 ppm) fractions on Cx. quinquefasciatus larvae. The highest mortality percent of the pupae were also recorded with N-hexane and chloroform fractions on An. gambiae at 2500 ppm. As for Cx. quinquefasciatus only 50 % and 36 % mortality were recorded with N-hexane and chloroform fractions respectively. CONCLUSION: The extract of A. senegalensis was toxic on immature stage of mosquito species tested. By splitting methanolic crude extract, only N-hexane and chloroform fractions were revealed to possess a mosquitocidal effects and could be considered and utilized for future immature mosquito vectors control.

Mosquitocidal properties of Bacillus species isolated from mangroves of Vellar estuary, Southeast coast of India.

Samples collected from the mangroves of Vellar estuary yielded a mosquitocidal bacterium, whose secondary metabolites exhibited mosquito larvicidal and pupicidal activity. The bacterium was isolated using standard microbiological methods and identified using classical biochemical tests. The mosquitocidal bacterium was identified as Bacillus subtilis, Bacillus thuringiensis, Bacillus sphaericus and Bacillus cereus. Mosquitocidal metabolite(s) was separated from the culture supernatant of the bacterium and its efficacy was against the larval and pupal stages of two different species of mosquitoes and determined in terms of LC50 and LC90. Mosquito larvicidal activity in terms of LC50 against Anopheleus stephensi and Aedes aegypti was 4.374 and 7.406 µl/ml and its pupicidal activity was 4.928 and 9.865 µl/ml, respectively. The present study proved that the mosquitocidal properties of the Bacillus species isolated from mangroves of Vellar estuary was evaluated as target species of mosquito vectors. This is an ideal eco-friendly approach for the vector control programs.