Artificial modification of the chemical composition of orange oil (Citrus sinensis L.) and its effect on larvicidal activity

The use of synthetic pesticide carries along several disadvantages talking about the preservation of the natural homeostasis of the planet, causing the searching of biopesticide, which one presents advantages as well as biodegradability in minimum possible time, the low toxicity in comparison to synthetic pesticides and their variety of structure, which allows slowing down the appearance of resistance. The aim of this work was to evaluate the effect on the larvicidal action when artificially varying the chemical composition of orange oil (Citrus sinensis L.). As results, we found that the analysis of gas chromatography coupled to mass spectrometry showed the presence of terpenoid and sesquiterpenoid compounds in the different samples. The use of electric pulses on samples modified their chemical composition, so that the percentage of limonene went from 72% in the sample that was not subjected to electric treatment to lower percentages, even in sample three the percentage of limonene was <50%. Only three compounds (limonene, linalool and caryophyllene) were found to be common in all samples. Subsequently, the larvicidal action on Drosophila melanogaster larvae was evaluated. Six concentrations of each oil sample were tested (0, 100, 500, 1000, 5000 and 10000 ppm). We found that there was no linear relationship between concentration and lethality. Additionally, in the sample without electrical treatment most of the concentrations tested had lethality higher than 50%, while in sample 7 the results of the lethality were lower than 30%, so that biological tests showed that in samples where the concentration of limonene was lower, the lethality in the larvae decreased.     

Comparative larvicidal activity of essential oils from three medicinal plants against Aedes aegypti L

This work aimed at comparing larvicidal activity of essential oils extracted from the dried leaves of Alpinia speciosa, Cymbopogon citratus, and Rosmarinus officinalis against Ae. aegypti larvae. The larvae were observed for 4 h and at 24 h according to a completely randomized design with three replications and the following concentrations [μl/ml]: 0.25, 0.5, 1.0, 1.5, 2.0, 2.5, and controls were distilled water, and commercial standard citral, camphor, eucalyptol, α‐pinene, and β‐myrcene. The essential oil of C. citratus had the lowest LC₅₀ (0.28) and LC₉₀ (0.56) values, followed by that of A. speciosa (0.94 and 1.2, resp.) and of R. officinalis (1.18 and 1.67, resp.), and only the commercial standards citral and α‐pinene were larvicidal.     

Piperonyl butoxide synergizes the larvicidal activity of Origanum vulgare essential oil and its major constituents against the larvae of Aedes albopictus and Culex pipiens quinquefasciatus

Mosquitoes bite human beings and transmit many diseases, such as malaria, dengue fever, and Zika virus. Vector control of mosquitoes is an effective strategy for reducing the spread of disease. However, extensive use of insecticides (e.g. pyrethroids and organophosphorus) has caused resistance in mosquitoes, which weakens the effectiveness of mosquito control. Phytochemicals have been considered an alternative approach to mosquito control. Essential oil (EO) was obtained from the leaves and flowers of Origanum vulgare, and its synergistic activity with piperonyl butoxide (PBO) was tested against Aedes albopictus and Culex pipiens quinquefasciatus larvae. Thirty-seven compounds were identified, among which carvacrol and thymol were two major constituents (30.73 % and 18.81 %, respectively). O. vulgare EO had a significant toxic effect against fourth-stage larvae of Cx. p. quinquefasciatus and Ae. albopictus, with LC₅₀ values of 17.51 and 75.90 mg/L. Carvacrol and thymol also each appeared to be more effective against Cx. p. quinquefasciatus (LC₅₀ = 19.30 and 11.56 mg/L, respectively) than Ae. albopictus (LC₅₀ = 26.62 and 26.66 mg/L, respectively). PBO interacted synergistically with O. vulgare EO, carvacrol and thymol with 2.60–6.26 times as much of the active compound needed without PBO as against Cx. p. quinquefasciatus and Ae. albopictus larvae. Overall, our results contribute to the development of new natural mosquito insecticides.     

Evaluation of larvicidal efficacy of Ricinus communis (Castor) and synthesized green silver nanoparticles against Aedes aegypti L.

Aedes mosquitoes are the most important group of vectors that transmit pathogens, including arboviruses, and cause human diseases such as dengue fever, yellow fever, Zika virus, and Chikungunya. Biosynthesis and the use of green silver nanoparticles (AgNPs) is a vital step to identify reliable and eco-friendly controls for these vectors. In this study, Aedes (Ae.) aegypti larvae (2nd and 3rd instar) were exposed to leaf extracts of Ricinus communis (Castor) and AgNPs synthesized from the extract to evaluate their larvicidal potential. Synthesized AgNPs were characterized by UV–Vis spectroscopy, Fourier transform infrared spectroscopy (FTIR), and energy-dispersive X-ray spectroscopy (XRD). Ae. aegypti larvae were treated with different concentrations (50–250 ppm) of the leaf extract and synthesized AgNPs. There were five replicates per treatment, in addition to a positive (temephos) and negative control (dechlorinated water). Mortality was recorded after 12, 24, 36, and 48 h and the data were subjected to Probit analysis. The nanoparticles were more toxic (LC₅₀ = 46.22 ppm and LC₉₀ = 85.30 ppm) than the plant extract (106.24 and 175.73 ppm, respectively). The leaf extracts of Ricinus communis were subjected to HPLC analysis to identify their chemical constituents. This study suggests that plant extracts and synthesized nanoparticles are excellent alternatives to hazardous chemical pesticides used to control vector mosquitoes. This is a potentially useful technique that can reduce aquatic toxicity from insecticide use.     

Larvicidal activity and Histopathological changes of Cinnamomum burmannii,Syzygium aromaticum extracts and their combination on Culex pipiens

In order to develop an eco-friendly botanical larvicide alternative to the synthetic larvicides, extracts were prepared from the Cinnamomum burmannii (C.B.) and Syzygium aromaticum (S.A.) with hexane using a sonicator. The extracts were evaluated for larvicidal activity individually and in combination against the Culex pipiens larvae. The LC₅₀ value of C.B. and the S.A. hexane extracts tested individually were 184.2 and 363.7 µg/mL against Cx. pipiens respectively. All the combinations of the extract of C.B. and S.A. showed synergistic factors higher than one. Among the different ratios of extracts, the SA25%: CB75% extract was found to be more toxic than the other combinations (LC₅₀:125.7 µg/mL). Midgut cells treated with S.A. 25%: C.B. 75% extract showed severe morphological alterations such as degradation of microvilli; degeneration of epithelial cells, and peritrophic membrane; loss of nuclei, irregular and damage of microvilli. The extract has a promising larvicidal potential against Cx. pipiens, However, the extract was toxic against HUVEC cells, as evident from MTT and cell morphology. Further investigation is required to assess the toxicity of the extract on aquatic animals.     

Mosquito larvicidal activity of pyrrolidine-2,4-dione derivatives: An investigation against Culex quinquefasciatus and molecular docking studies

The pyrrolidine-2,4-dione derivatives were used to conduct a larvicidal test on Culex quinquefasciatus larvae of the second instar. Mannich base condensation method was used to synthesis the pyrrolidine-2,4-dione derivatives by grindstone method. The reaction conditions were mild, resulting in high yields. An analysis of the synthesized compounds was carried out using FTIR, ¹H NMR, ¹³C NMR, mass spectrometry, and elemental analysis. Synthesized compounds (1a-h) were evaluated for larvicidal activities. Compound 1e (LD₅₀: 26.06 µg/mL), and 1f (LD₅₀: 26.89 µg/mL), and were notably more active against Culex quinquefasciatus than permethrin (LD₅₀: 26.14 µg/mL). The docking studies also demonstrated that 1e, and 1f are potent larvicides with higher binding energy (?12.6 kcal/mol) than the control in the mosquito odorant binding protein (PDB ID: 3OGN). The larvicidal properties of lead molecules have made them important for use as insecticides.     

冬青油与肉桂油对淡色库蚊的生物活性

为进一步明确冬青油（wintergreen oil）与肉桂油（cinnamon oil）对蚊虫的生物活性, 本研究采用浸液法、 “Y”型嗅觉仪法和密闭三角瓶熏蒸法, 分别测定了两种精油对淡色库蚊Culex pipiens pallens幼虫的毒杀作用以及对成虫的驱避和熏杀活性。结果显示： 肉桂油和冬青油对淡色库蚊幼虫均具有较强的毒杀作用, 处理24 h的LC₅₀分别为71.87 mg/L和 102.83 mg/L。在0.5 μL的供试剂量下, 冬青油与肉桂油在20 min内对淡色库蚊的驱避率均在80%以上, 显示了较好的驱蚊活性。冬青油对淡色库蚊具有明显的熏蒸击倒作用, 12 μL/L浓度下的KT₅₀为3.97 min; 而肉桂油则具有较好的熏蒸致死活性, 熏蒸5 h的LC₅₀ 为0.31 μL/L。冬青油与肉桂油按1∶1体积比混配后对淡色库蚊表现出较好的击倒和致死效果。冬青油和肉桂油既对淡色库蚊幼虫具有较强的毒杀作用, 又对淡色库蚊雌成虫表现出较好的驱避和熏杀活性, 具有开发成为植物源蚊虫防控剂的潜力。     

Larvicidal potential of gold and silver nanoparticles synthesized using Acalypha fruticosa leaf extracts against Culex pipiens (Culicidae: Diptera)

Plant secondary metabolites have been recently used for the synthesis of different nanoparticles. The present investigation aimed at evaluating the effect of gold (AuNPs) and silver (AgNPs) nanoparticles synthesized using Acalypha fruticosa leaf extracts to control the mosquito Culex pipiens. The A. fruticosa AuNPs and AgNPs spectra displayed their maximum absorption at 550 nm and 440 nm, respectively. The infrared spectra revealed different functional groups related to different chemical compounds. The larval mortality of aqueous leaf extract of A. fruticosa was 499.54 ppm (LC₅₀) and 1734.06 ppm (LC₉₀) after 24 h of treatment. This study revealed that AuNP (LC₅₀, 30.2 and LC₉₀, 104.83 ppm) and AgNP (LC₅₀, 52.86 and LC₉₀, 157.227 ppm) preparations were highly effective compared to the A. fruticosa extract alone and also more affordable, as a smaller amount was required. The present findings show the potential larvicidal effect of the synthesized AuNPs and AgNPs for the control of mosquito-mediated disease transmission.     

Larvicidal,ovicidal activities and histopathological alterations induced by Carum copticum (Apiaceae) extract against Culex pipiens (Diptera: Culicidae)

An experiment was carried out, firstly, to determine the possible toxicity of Carum copticum (Apiaceae) extract against Culex pipiens (Diptera: Culicidae), and, secondly, to study the histopathological alterations in the midgut of Cx. pipiens as a result of treatment with C. copticum extract. Larvicidal and ovicidal activities of C. copticum extract against the larvae of Cx. pipiens was determined according to World health organization (WHO). The inhibition effect of C. copticum was assessed by determining the mortality of the treated larvae and eggs. The histopathological effect of the C. copticum extracts on midgut epithelium of the larvae was examined under both light and transmission electron microscopy. The crude extract of C. copticum exerted 100% mortality for Cx. pipiens after 24 h at 200 μm/ml, and zero hatchability (100% mortality) at 150 μm/ml for Cx. pipiens. The histopathological study showed that larvae treated with C. copticum extract had cytopathological alterations of the midgut epithelium. The study provided information on various effects of C. copticum extract against Cx. pipiens.     

Larvicidal activity of some fungal extracts on Aedes caspius and Culex pipiens (Diptera: Culicidae)

A preliminary study was conducted to evaluate the effects of nine methanol fungal extracts on fourth instar larvae of Aedes caspius and Culex pipiens (Diptera: Culicidae). None of the extracts tested showed larvicidal activity except for the Paecilomyces lilacinus extract, which showed 100 % mortality against the larvae of Ae caspius after 24 h. The LC₅₀ values of the P. lilacinus extract after 24 h were 190.66 μg/mL against Ae. caspius and 254.25 μg/mL against Cx. pipiens, respectively. After 48 h, meanwhile, the LC₅₀ values were 65.70 and 164.13 μg/mL, respectively. Histological analysis of the midgut of the treated larvae of Ae. caspius and Cx. pipiens revealed changes such as cell destruction, spacing between the cells and disruption of the microvilli, resulting in an appearance of vacuolization in the midgut. This article is the first report of the use of P. lilacinus extract for the control of Ae. caspius and Cx. pipiens larvae and the data obtained may help to provide a better understanding of the mode of action of P. lilacinus as an insecticide against mosquito larvae.     

Evaluation of larvicidal activity of esters of 4-mercapto-2-butenoic acid against Aedes albopictus (Diptera: Culicidae)

Aedes albopictus (Skuse) (Diptera: Culicidae), an aggressive and annoying vector of several arbovirus including Chikungunya and Zika, is a serious health problem worldwide. Control of this mosquito is difficult because of high adaptability, egg resistance to dehydration and ability to exploit many man-made microhabitats. The most effective strategy appears the control of larval population. Based on previous data showing a larvicidal effect of plant extracts containing sulfhydryl and isothiocyanate compounds, we evaluated by bioassays the toxicity of three synthetic esters of 4-mercapto-2-butenoic acid on larvae of A. albopictus in comparison to cypermethrin. Among the compounds tested, the most effective was n-octyl 4-mercapto-2-butenoate, about 5 times more effective than ethyl 4-mercaptobut-2-enoate and about 20 times more effective than menthyl 4-mercaptobut-2-enoate. We advance the hypothesis that the larvicidal properties of n-octyl 4-mercapto-2-butenoate are due to its hydrophobic alkyl chain, longer than that of the other two compounds. This chain confers to the molecule the ability to spread on water surface and interfere with larval respiration. The larvicidal activity of n-octyl 4-mercapto-2-butenoate against A. albopictus appears interesting and may be developed after toxicological evaluation on vertebrates and humans, and environmental toxicity tests in compliance with WHO and ECDC rules.     

Repellent,larvicidal and adulticidal activities of essential oil from Dai medicinal plant Zingiber cassumunar against Aedes albopictus

Zingiber cassumunar is an important plant used in traditional medicine and as a natural mosquito repellent. However, the compounds responsible for the repellent activity of the plant are still unknown. The aim of the study is to identify the components of Z. cassumunar essential oil that show repellent activity against Aedes albopictus. We also evaluated the larvicidal and adulticidal activities of Z. cassumunar essential oil against Ae. albopictus. In-cage mosquito repellent experiments showed that Z. cassumunar essential oil possessed moderate repellent activity with a minimum effective dose (MED) of 0.16 ± 0.01 mg/cm², compared to reference standard N,N-diethyl-3-methylbenzamide (DEET, 0.03 ± 0.01 mg/cm²). Bioassay-guided fractionation identified the major active compound of Z. cassumunar essential oil as (−)-terpinen-4-ol (1) (MED: 0.19 ± 0 mg/cm²). We also found that Z. cassumunar essential oil showed moderate larvicidal activity against first instar larvae of Ae. albopictus with a LC₅₀ (50% lethal concentration) of 44.9 μg/L after 24 h. Fumigation bioassays showed that Z. cassumunar essential oil exhibits moderate adulticidal activity against Ae. albopictus with a LC₅₀ of 5.44%, while (−)-terpinen-4-ol showed significant adulticidal activity with a LC₅₀ of 2.10% after 24 h. This study verifies that the Z. cassumunar essential oil has mosquito repellent activity, and that (−)-terpinen-4-ol is mainly responsible for this activity. Furthermore, this study provides scientific support for the folk usage of Z. cassumunar essential oil as mosquito repellent and indicates that Z. cassumunar essential oil and (−)-terpinen-4-ol can be used as plant-derived repellents and insecticides for mosquito control.     

Bioassay-guided fractionation of a dried commercial source,Alpinia galanga (L.) Willd rhizomes extract,against Culex pipiens (Diptera: Culicidae)

The increasing risk of insecticide resistance in mosquito populations has led to the search for new larvicidal agents. Evaluation of bioassay-guided fractionation of the rhizome extract of Alpinia galanga (L.) Willd against Aedes aegypti was assessed. Bioactive fractions were isolated from the rhizome extract of A. galanga using a Soxhlet extractor and chromatography techniques, and subsequently tested against the fourth instar of Culex pipiens. The lethal concentration (LC) was calculated via log-probit analysis. The active fraction was evaluated by gas chromatography-mass spectroscopy (GC–MS) and infrared (IR) analysis. The highest larvicidal potential obtained from bioassays using the Soxhlet apparatus was observed in dichloromethane (DCM) and ethyl acetate (EtoAc) extracts, with LC₅₀ values of 124.49 and 176.30 ppm, respectively, after 24 h of exposure. Subsequently, the DCM extract was subjected to column and thin-layer chromatography. Results of the DCM extraction and the active TLC fraction (F133) of the Rf value 0.5 revealed that LC₅₀ and LC₉₀ values decreased over time. The F133 fraction of A. galanga exhibited zero hatchability (100% mortality) at LC₅₀ (63.416 ppm) and LC₂₅ (31.70 ppm) against Cx. pipiens eggs. GC–MS analysis of the active thin-layer chromatography TLC fraction (F133) revealed the presence of phenol 2 4-bis (1 1-dimethylethyl), which was identified as the major compound. Alpinia galanga extract is a promising candidate for the control of mosquito populations. Further study is required to determine the effect of the extracts on non-target organisms.     

Chicory (Cichorium intybus) and wormwood (Artemisia absinthium) extracts exhibit strong larvicidal activity against mosquito vectors of malaria,dengue fever,and filariasis

Vector-borne diseases transmitted by mosquitoes cause globally important diseases such as malaria, dengue fever, and filariasis. The incidence of these diseases can be reduced through mosquito control programs but these control programs currently rely on synthetic insecticides that can impact the environment, and has selected widespread mosquito resistance. Environment friendly and biodegradable natural insecticides discovered in plants offer an alternative approach to mosquito control. Here, we investigated extracts from root or aerial parts of Chicory (Cichorium intybus) and wormwood (Artemisia absinthium) against the early 4th instar larvae of Anopheles stephensi (malaria vector), Aedes aegypti (dengue fever vector), and Culex quinquefasciatus (filariasis vector). The root and aerial parts extracts of A. absinthium and C. intybus at 200, 100, 50, 25 and 12.5?ppm caused significant mortality of the tested mosquito species. Root extracts exhibited higher larvicidal activity that aerial part extracts. The highest larvicidal activity was recorded in methanol extract of roots of C. intybus with LC50?=?66.16, 18.88 and LC¬90?=?197.56, 107.16?ppm for An. stephensi; LC50?=?78.51, 40.15 and LC90?=?277.31, 231.28?ppm for Ae. aegypti and LC50?=?103.99, 64.56 and LC¬90?=?314.04, 247.54?ppm for Cx. quinquefasciatus. These results reveal potent mosquito larvicidal activity against vectors of malaria, dengue fever, and filariasis is present in extracts of chicory and wormwood.     

Comparative delta-endotoxins of Bacillus thuringiensis against mosquito vectors (Aedes aegypti and Culex pipiens)

Pure crystals of seven Bacillus thuringiensis field isolates from the Lower Silesia region (Poland) were tested against larvae of Aedes aegypti L. and Culex pipiens L. (Culicidae, Diptera). The crystals of OpQ3 phylloplane isolate (belonging to the first biochemical type of B. thuringiensis subsp. japonensis, yoso, jinghongiensis) killed from 68 +/- 7% to 84 +/- 7% of the fourth instar larvae of A. aegypti. The crystals of two other strains (KpF3 and KpC1) of this group caused mortality between 3 +/- 2% and 70 +/- 7%. The LC50 ranged from 3.2 +/- 0.4 to 34.1 +/- 4.8 microg/ml. The effect of B. thulringiensis wratislaviensis H-47 crystals was the lowest with larval mortality from 0% to 17 +/- 3%. No significant (0%-37 +/- 6%) effect of B. thuringiensis crystals on the larvae of C. pipiens was observed. Our results show that the delta-endotoxins of B. thuringiensis act very specifically.     

Virulence of entomopathogenic fungi against Culex pipiens: Impact on biomolecules availability and life table parameters

Culex pipiens mosquitoes considered as vectors for many arboviruses such as the West Nile virus and encephalitis virus showing a global impact on human health. The natural management of the aquatic stages of this pest is crucial for maintaining an insecticide-free and sustained environment. The present work focused on studying the biological and biochemical effects of the entomopathogenic fungi: Metarhizium anisopliae, Beauveria bassiana, and Paecilomyces lilicanus, against 3^rd instar larvae of Culex pipiens laboratory colony. The results revealed that M. anisopliae showed maximum larval mortality (88%) with the lowest lethal time (LT₅₀) (22.6 hrs) at 10⁸ spores/ml followed by B. bassiana (73.33%) with LT₅₀ (38.35 hrs), while P. lilicanus showed minimum percent mortality (65%) with highest LT₅₀ (51.5 hrs). The median lethal concentration (LC₅₀) values were found to be 1.027 × 10⁵ spores/ml for M. anisopliae, 1.24 × 10⁶ spores/ml for B. bassiana, while it was 8.453 × 10⁶ spores/ml for P. lilicanus. A reduction in female fecundity, number of hatched eggs, pupation and adult emergence percentage were recorded. The biochemical analysis of the treated larvae revealed different quantitative decrease in total soluble proteins, lipids, and carbohydrate hydrolyzing enzymes compared to control. Histopathological effects of fungal infection upon insect cuticles, muscles, and midgut were investigated. Based on the obtained results, M. anisopliae proved its superior virulent effect as a bio-control agent against Cx. pipiens.     

Chemical composition and larvicidal activity of essential oils from Piper species

The larvicidal activity of essential oils of four species of Piper from the Amazon Forest was tested using third-instar larvae of Aedes aegypti. The oils were extracted by steam distillation and analyzed by GC and GC–MS. The main components isolated from each Piper species were as follows: viridiflorol (27.50%), aromadendrene (15.55%) and β-selinene (10.50%) from Piper gaudichaudianum; β-selinene (15.77%) and caryophyllene oxide (16.63%) from Piper humaytanum; dillapiol (54.70%) and myristicin (25.61%) from Piper permucronatum; and asaricin (27.37%) and myristicin (20.26%) from Piper hostmanianum. Amongst all essential oils tested, the most active against larvae of A. aegypti was the oil extracted from P. permucronatum, with a LC₅₀ = 36 μg/ml (LC₉₀ = 47 μg/ml), followed by the essential oil of P. hostmanianum, with a LC₅₀ = 54 μg/ml (LC₉₀ = 72 μg/ml). The oils with higher content of arylpropanoids were more active against larvae of A. aegypti.     

41种植物精油对淡色库蚊的熏蒸活性

为发现具有较高杀蚊活性的精油, 推动植物精油类卫生杀虫剂的创制, 本研究采用三角瓶熏蒸法测定了17科41种植物精油对淡色库蚊Culex pipiens pallens雌成蚊的熏蒸活性, 并进一步采用密闭圆筒法验证其杀虫毒力大小。三角瓶熏蒸法测定表明, 在12 μL/L浓度下, 留兰香油（spearmint oil）、 薰衣草油（lavender oil）、 山苍子油（Litsea cubeba oil）等26种精油均有较强的熏蒸作用, KT₅₀小于15 min。该26种精油用密闭圆筒熏蒸法进一步测定表明, 在浓度为10 μL/L时, 冬青油（wintergreen oil）、 艾叶油（blumea oil）、 薄荷油（peppermint oil）、 桉叶油（Eucalyptus robusta oil）和蓝桉油（E. globulus oil）等植物精油熏蒸活性较强, 其KT₅₀分别为16.91, 21.20, 22.57, 18.43和19.48 min。结果证明冬青油、 艾叶油、 薄荷油、 桉叶油和蓝桉油等5种精油对淡色库蚊具有较强的熏蒸活性, 具备作为淡色库蚊防控剂开发的潜力, 值得进一步研究。     

Mosquito larvicidal activity of Aloe vera (Family: Liliaceae) leaf extract and Bacillus sphaericus,against Chikungunya vector,Aedes aegypti

The bio-efficacy of Aloe vera leaf extract and bacterial insecticide, Bacillus sphaericus larvicidal activity was assessed against the first to fourth instars larvae of Aedes aegypti, under the laboratory conditions. The plant material was shade dried at room temperature and powdered coarsely. A. vera and B. sphaericus show varied degrees of larvicidal activity against various instars larvae of A. aegypti. The LC₅₀ of A. vera against the first to fourth instars larvae were 162.74, 201.43, 253.30 and 300.05 ppm and the LC₉₀ 442.98, 518.86, 563.18 and 612.96 ppm, respectively. B. sphaericus against the first to fourth instars larvae the LC₅₀ values were 68.21, 79.13, 93.48, and 107.05 ppm and the LC₉₀ values 149.15, 164.67, 183.84, and 201.09 ppm, respectively. However, the combined treatment of A. vera + B. sphaericus (1:2) material shows highest larvicidal activity of the LC₅₀ values 54.80, 63.11, 74.66 and 95.10 ppm; The LC₉₀ values of 145.29, 160.14, 179.74 and 209.98 ppm, against A. aegypti in all the tested concentrations than the individuals and clearly established that there is a substantial amount of synergist act. The present investigation clearly exhibits that both A. vera and B. sphaericus materials could serve as a potential larvicidal agent. Since, A. aegypti is a container breeder vector mosquito this user and eco-friendly and low-cost vector control strategy could be a viable solution to the existing dengue disease burden. Therefore, this study provides first report on the mosquito larvicidal activity the combined effect of A. vera leaf extract and B. sphaericus against as target species of A. aegypti.     

Synthesis of some novel phosphorylated and thiophosphorylated benzimidazoles and benzothiazoles and their evaluation for larvicidal potential to Aedes albopictus and Culex quinquefasciatus

Series of benzimidazole and benzothiazole linked phosphoramidates and phosphoramidothioates (5a–j) and benzimidazole linked phenylphosphoramidates and phenylphosphoramidothioates (10a–e) were synthesized. The title compounds were preliminary screened for mosquito larvicidal properties against Aedes albopictus and Culex quinquefasciatus at different concentration from 40 to 5 mg/L. Among the screened compounds three compounds revealed potential larvicidal effects with 100% mortality in the order of 10e > 5j > 5e. Compound 10e was found to be the most toxic compound to Ae. albopictus and Cx. quinquefasciatus. The LC₅₀ of 10e against Ae. albopictus was found to be 6.42 and 5.25 mg/L at 24 and 48 h, respectively, whereas it was 7.01 and 3.88 mg/L, respectively in Cx. quinquefasciatus. Temephos was used as positive control.