Insecticidal activity and physiopathological effects of Cotula cinerea crude extract against Culex pipiens

@#The development of new alternatives strategies to synthetic insecticides aimed at reducing pest populations by developing pesticides based on plant extracts without negative effects in non target organisms and environment. The present study was undertaken in order to assess the insecticidal activity of the crude methanolic extract of the Algerian Asteraceae Cotula cinerea, against the larval and the pupal stage of Culex pipiens (Diptera: Culicidae). It is also to determine the chemical composition of the used extract, and to understand the mechanism of toxic action of the tested extract. Based on the preliminary tests, five concentrations of the crude methanolic extract of C. cinerea (0.62, 1.25, 2.50, 3.75, and 5 mg/mL) were tested for their insecticidal activity according to the protocol recommended by the World Health Organization. The chemical profile of the extract was also obtained by high performance liquid chromatography (HPLC). Histopathological effects and inhibition of acetylcholinesterase activity in treated mosquitoes with LC90 were examined to elucidate the mechanism of the toxic effect of the tested extract (48 h post treatment). Eight compounds have been identified by HPLC. That includes four flavonoids (rutin, quercetin, myrcetin and cathechin), three phenolic acids (benzoic acid, vanillic acid, p-coumaric acid) and one alkaloid (berberine). C. cinerea methanolic extract showed good larvicidal and pupicidal activities with LC50 and LC90 values of 1.10 and 4.37 mg/mL respectively against pupae, 24h post treatment and 1.26, 2.35 mg/mL respectively against the fourth instar larvae. Data of enzymatic assay performed on LC50 and LC90 pupae and larvae revealed prominent neurotoxic effects. C. cinerea extract reduced the activity of acetylcholinesterase (AChE) enzyme in a concentration dependent manner. Obtained inhibition percentages, 48 h after treatment, were 35.11 ± 7.44 and 51.83 ± 4.04% for pupal stage and 30.98 ± 2.97 % and 48.77 ± 4.72% for the fourth instar larvae for LC50 and LC90 values respectively. Treated larvae and pupae showed also histopathological damages in the pupal cuticle and larval midgut. The results of this study showed that C. cinerea crude methanolic extract could be considered as an eco-friendly alternative for mosquito control.

Biocontrol potential of Beauveria bassiana and Metarhizium anisopliae isolates from Turkey against Hyphantria cunea (Drury) (Lepidoptera: arctiidae) Larvae under laboratory and field conditions

Hyphantria cunea is one of the most important pest insects causing significant damage in many plant species. The present study aimed to evaluate the insecticidal activity of Turkey isolates of Beauveria bassiana and Metarhizium anisopliae against H. cunea larvae under laboratory and field conditions. B. bassiana isolates YK16, YK23 and YK26, and M. anisopliae isolates YK41 and YK45 were sprayed onto the larvae of H. cunea at the respective doses of 1x105 and 1x106 conidia mL-1 and monitored for seven days. Fungal isolates, bio-insecticide Bacillus thuringiensis and chemical insecticide diflubenzuron were used in field studies. Trials were carried out in five replications. All B. bassiana isolates caused 100% mortality on first instar larvae in laboratory trials. Mortality ratios ranged from 100 to 96% on second instar larvae. M. anisopliae isolates YK45 and YK41 caused 88 and 84%, and 81.33 and 77.11% mortalities for the first and second instar larvae, respectively. The mortality rates fluctuated between 91.78-72.89% for B. bassiana on third instar larvae in laboratory conditions. However, M. anisopliae isolates YK45 and YK41 caused 77.11 and 60.22% mortality on third instar larvae, respectively. In the field trials, B. bassiana YK23 displayed promising insecticidal activity with 80.60% mortality on second instar larvae of H. cunea. Other isolates as well caused mortalities ranging from 60.77 to 49.55%. The results revealed that some isolates of B. bassiana and M. anisopliae have potential to control H. cunea larvae. However, additional detailed studies need to be carried out to increase their effectiveness in field conditions.

Phytochemical composition of almond oil from Melia azedarach L. and its larvicidal, ovicidal, repellent and enzyme activities in Culex pipiens L

@#Melia azedarach L. (Meliaceae) is a botanical species with focal point of global research for its biological properties. The Melia azedarach tree is distinguished by its rapid growth, its adaptation to different temperate zones, as well as its insecticidal properties. All this made us think of exploiting it in biological control against different stages of mosquitoes. To this end, we aim, through the present work, to evaluate the effectiveness of Melia azedarach extracts against Culex pipiens mosquito. More specifically, our study focuses on determining the chemical composition of Melia almond oil, as well as the larvicidal, ovicidal and repellent activities on Culex pipiens L. mosquito as well as the activities of acetylcholinesterase (AChE) and glutathione-S-transferase (GST). Almond oil was extracted by a Soxhlet and subjected to gas chromatography–mass spectrometry (GC/MS). The yield was found to be 35.17%. The chemical composition revealed the presence of various phytoconstituents. A total of 7 compounds were identified, the main ones being 9,11-Octadecadienoic acid, methyl ester, (E,E)- (79.32%), 9-octadecenoic acid (Z)-, methyl ester (13.24%), hexadecanoic acid and methyl ester (3.69%). The larvicidal bioassays were performed according to the protocol recommended by the World Health Organization with concentrations varying from 20 to 80 mg/L depending on the exposure time (24, 48 and 72 hours). The almond oil exhibited remarkable larvicidal activity against fourth instar larvae and the lethal concentrations were determined (LC25= 23.70 mg/L, LC50=35.49 mg/L, LC90=79.61 mg/L). The results also showed that the oil caused an ovicidal activity with a significant effect on egg hatch. The recorded hatching percentages were respectively 88.79% and 72.40% for the LC25 and LC50, and this compared to the control series. Moreover, this oil exhibited significant repellency against adult mosquitoes. Furthermore, the enzymatic measurements performed on LC50 and LC90 treated larvae revealed a neurotoxic activity and a stimulation of the detoxification system as evidenced, respectively, by an inhibition of AChE and induction in GST activity. Overall, our data proved that Melia azedarach almond oil could be considered as a potent biorational alternative to synthetic insecticides for mosquito control.

Synergistic effects of binary mixtures of linalool with pyrethroids against fall armyworm / Efeitos sinérgicos de misturas binárias de linalol com piretroides contra lagarta-do-cartucho

The present work aimed to determine the toxicity of linalool and evaluate the lethal and toxic effects of linalool associated with pyrethroids in binary mixtures to fall armyworm (Spodoptera frugiperda). The insects used in the experiment were obtained from stock breeding initiated from larvae collected from conventional corn plants, grown in an experimental area, in the city of Uberlândia, Minas Gerais. Also, it was obtained essential oil from a variety of Ocimum basilicum, with a high content of linalool (80%), found naturally, as a measure of comparison of different linalool (97.5%) assays. Dose-response bioassays with 3rd instar larvae were performed to determine lethal dose for 50% mortality (LD50) of linalool. Toxicity tests were also performed with O. basilicum essential oil and with pyrethroid insecticides: deltamethrin and its commercial product (Decis 25 EC, Bayer®). After this, combinations between different doses of these products were made and applied on 3rd instar larvae of Spodoptera frugiperda (Smith). Linalool presented high toxicity to S. frugiperda (LD50 = 0.177 µL a.i. µL-1). It was observed neurotoxic effects after the linalool application since the insects presented an aspect of confusion, followed by extreme agitation and finally death. All binary mixtures caused mortality higher than the products applied alone (deltamethrin and linalool) used at 100% LD50, except to 75% LD50 deltamethrin added to 25% LD50 linalool, whose mortality did not differ the products alone, in 24 hours. It was obtained over 90% larval mortality when linalool was combined with 25% LD50 of deltamethrin, in 24 and 48 hours after application, and over 80% of mortality when linalool was combined with 25% LD50 of Decis, only in 48 hours after application. We conclude that linalool is a potential insecticidal and can be associated with pyrethroids to control of S. frugiperda. Further studies are required in order to evaluate the synergistic combinations against field populations of S. frugiperda.

O objetivo deste trabalho foi determinar a toxicidade do linalol e avaliar os efeitos tóxicos e letais do linalol associado a piretroides em misturas binárias para lagarta do cartucho do milho (Spodoptera frugiperda). Os insetos utilizados no experimento foram obtidos de criação estoque iniciada a partir de larvas coletadas em plantas de milho convencional, cultivado em área experimental, no município de Uberlândia, Minas Gerais. Também foi obtido óleo essencial de uma variedade de Ocimum basilicum, com alto teor de linalol (80%), encontrado naturalmente, como medida de comparação para ensaios com linalol (97.5%). Os bioensaios do tipo dose-resposta com larvas de 3º instar foram realizados para determinar a dose letal do linalol para 50% de mortalidade da população (DL50). Também foram realizados testes de toxicidade com óleo essencial de Ocimum basilicum e com inseticidas piretroides: deltametrina e seu produto comercial (Decis 25 EC, Bayer®). Em seguida, foram realizadas combinações entre diferentes doses desses produtos e aplicadas em larvas de 3º instar de Spodoptera frugiperda (Smith). De acordo com os resultados, observou-se que o linalol apresentou alta toxicidade para S. frugiperda (DL50 = 0,177 µL a. i. µL-1). Foram observados efeitos neurotóxicos após a aplicação do linalol, uma vez que os insetos apresentaram um aspecto de confusão, seguido de extrema agitação e, por fim, morte. Todas as combinações binárias causaram mortalidade maior que os produtos aplicados isoladamente (deltametrina e linalol) utilizando-se 100% da DL50, exceto para 75% DL50 de deltametrina somada a 25% DL50 de linalol, cuja mortalidade não diferiu dos produtos isolados, em 24 horas após a aplicação. Foi obtida mais de 90% de mortalidade de larvas quando se combinou linalol com 25% da DL50 de deltametrina, em 24 e 48 horas após a aplicação, e mais de 80% de mortalidade quando se combinou linalol com 25% da DL50 do produto comercial, somente 48 horas após a aplicação. Concluímos que o linalol é um potencial inseticida e pode ser associado a piretroides no controle de S. frugiperda. Mais estudos são necessários em vista de avaliar as combinações sinérgicas contra populações de campo de S. frugiperda.

Genetic engineering of crops for insect resistance: An overview

Phytophagous insect incidence is a serious threat for reduction of crop productivity globally. There is anestimation of one fourth of crop is being destroyed by insects annually. Indeed, the development of insectresistant crops is a great milestone in agriculture to increase crop yield and reduce pesticide dependency.Genetic engineering facilitates development of insect resistant crops by expressing bacterial d-endotoxins andvegetative insecticidal proteins and other plant genes like lectins, protease inhibitors, etc. In addition, RNAinterference and genome editing through CRISPR Cas9 also provides new solutions for the development ofinsect-resistant crops. The resultant genetically modified crops showed resistance against lepidopteran, dipteran, homopteran and coleopteran insects. The insect-resistant crops have made a significant economic impactworldwide in terms of higher yield and low pesticide usage. In this review, we focus on different strategies fordeveloping transgenics against insect pest control by expressing different insecticidal proteins in crops

Research progress on chemical constituents of diterpenoids of Euphorbiae Ebracteolatae Radix and its pharmacological activities / 中草药

Euphorbiae Ebracteolatae Radix is the dry root of plant Euphorbia fischeriana or E. ebracteolata of Euphorbiaceae, which is a widely utilized natural medicine with broad development prospect. It has been discovered that Euphorbiae Ebracteolatae Radix contains several biologically active constituents, among which diterpenoids are the most important. The diterpenoids of Euphorbiae Ebracteolatae Radix contain eight types including abietane-type, tigliane-type, pimarane-type, rosane-type, cembrane-type, ent-kaurane-type, ingenane-type and atisane-type. Diterpenoids of Euphorbiae Ebracteolatae Radix have significant anti-tumor, anti-inflammatory, anti-viral and other pharmacological activities. In this paper, the chemical constituents of diterpenoids and pharmacological activities of Euphorbiae Ebracteolatae Radix in recent years were reviewed in order to provide references for better developing the resources of Euphorbiae Ebracteolatae Radix and its clinical application.

Bioactivity of Schinus molle L. and Schinus terebinthifolia Raddi. Essential Oils on Anticarsia gemmatalis (Hübner 1818)

Abstract Anticarsia gemmatalis is one of the main pests of the soybean crop, being controlled mainly with agrochemicals. The environmental and health risks, as well as the development of resistance by the pests, has led to the search for alternative control measures, aiming to use more eco-friendly procedures. The objective of this research was to evaluate the chemical composition and the bioactivity of Schinus molle and Schinus terebinthifolia essential oils (EOs) on A. gemmatalis. The major compound in both EOs was α-pinene (60.04 wt.% for S. molle and 38.49 wt.% for S. terebinthifolia). Bioassays were carried out with third instar larvae, with five replicates and each replicate with ten larvae, totaling 50 larvae per treatment. The oils were incorporated in the artificial diet (0.1, 0.5, 1.0, 1.5, and 2.0% v/v). The controls were: water, Tween-80® 0.5% v/v, and novaluron 0.075% v/v. According to the Probit method, the S. terebinthifolia EO presented a LC50 of 1.74% v/v (1.58-1.97% v/v); it was not possible to determine the LC50 for the S. molle EO. The mortality percentage after 24 and 48 h was 52% and 30% at 2.0% v/v for S. terebinthifolia and S. molle oil, respectively. After 72 h, the mortality rate for S. molle EO have not changed; for S. terebinthifolia EO it increased to 70%; the larvae treated with the chemical control (synthetic insecticide) had a mortality of 100%.

Phytofabrication of silver nanoparticles using Annona reticulata and assessment of insecticidal and bactericidal activities

Aim: Silver nanoparticle synthesis using plant products is now popular due to its environment friendly, easy availability, simple procedure and fascinating properties. In this study, an attempt was made on leaf extract of Annona reticulata L silver nanoparticles to synthesize and to assess its bactericidal and insecticidal properties. Methodology: Using plant material for silver nanoparticle synthesis is one of the bottom up approaches of silver nanoparticle synthesis. In the present study leaf extract of Annona reticulata was used for nanoparticle synthesis. The synthesized nanoparticles were characterized by X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR) and Energy Dispersive X-Ray Analysis (EDAX). The bactericidal property was evaluated against E. coli, P. aeruginosa, S. aureus, B. subtilis and P. vulgaris where as insecticidal property was tested against mosquito larvae and Sitophilus oryzae. Results: The XRD spectrum confirmed the formation of silver nanoparticles. SEM observation showed that nanoparticles were 17.33 nm in size and spherical in shape. The EDAX result revealed the presence of silver in the suspension. Silver nanoparticles exhibited higher repellency against Sitophilus oryzae and feeding deterrence. The nanoparticles possessed a strong larvicidal activity when they were used against fourth instar larvae of mosquitoes. The silver nanoparticles showed bactericidal activity against Pseudomonas aeruginosa, Proteus vulgaris, Bacillus subtilis, Staphylococcus aureus and Escherichia coli. Interpretation: The present study strongly suggests that Annona reticulata leaf extract can be used to fabricate silver nanoparticles with potent insecticidal and bactericidal properties.

Insecticidal activities and mechanism of extracts from neem leaves against Oxya chinensis / Atividade e mecanismos inseticidas de extratos de folhas "neem" contra Oxya chinesis

In this study, neem leaves were successively extracted with petroleum ether, 95% ethanol and water and the insecticidal activities of these extracts against Oxya chinensis larvae were measured. The results showed that 95% ethanol extract gave the highest extraction yield and insecticidal activity, and it was further extracted with five different solvents. The petroleum ether extract from the 95% ethanol extract possessed the highest insecticidal activity with median lethal concentration values ranging from 14.93 to 55.66mg/mL. The gas chromatography-mass spectrometer analysis showed that the petroleum ether extract mainly composed of alkanes, olefin, esters and amide. The pathological examination revealed that the prominent lesions, including reduced regenerative cells in midgut and swelled and degenerated cylindrical cells, were observed in the 5th instar Oxya chinensis after treatment. The ultrastructural features showed that the cylindrical cells, microvilli and mitochondria were seriously damaged. These results suggested that the petroleum ether extract from neem leaves had potent insecticidal activity and could be a candidate insecticide.(AU)

Nesse estudo, folhas "neem" foram extraídas com sucesso com éter de petróleo, 95% de etanol e água, e as atividades inseticidas desses extratos foram medidas contra larvas de Oxya chinesis. Os resultados mostram que extrato com 95% de etanol deram o maior resultado de extração e atividade inseticida e foi então extraído utilizando mais cinco diferentes solventes. O éter de petróleo do extrato de 95% etanol apresentou maior atividade inseticida com concentração letal média variando de 14.93 a 55.66mg/mL. A análise por cromatografia de massa mostrou que o extrato de éter de petróleo está composto principalmente de alcanos, alcenos, ésteres e amidas. A avaliação patológica revelou que as lesões proeminentes, inclusive células regenerativas reduzidas no intestino e células cilíndricas edemaciadas e degeneradas foram observadas no quinto estágio de desenvolvimento da Oxya chinesis após tratamento. As características ultraestruturais mostraram que as células cilíndricas, microvilos e mitocôndrias apresentavam lesões graves. Esses resultados sugerem que o extrato de éter de petróleo de folhas de "neem" tem atividade inseticida potente e pode ser um candidato a inseticida.(AU)

Bio-efficacy of Long Lasting Insecticidal Mosquito Nets (LLINs) on Malaria Vector Anopheles Mosquitoes in Malaria-Endemic Areas of Myanmar

Sixty used Long Lasting Insecticidal Nets (LLINs) from six malaria endemicareas of States and Regions of Myanmar were assessed for their bio-efficacy againstAnopheles mosquitoes. Total ten nets were collected from the randomly selectedhousehold of each area. Insecticide susceptibility and bio-efficacy test were doneaccording to WHO testing method. Results revealed that a total of 4470 mosquitoes of 12Anopheles species including main vector and secondary vectors were collected in highdensity in Beelin, Taungoo, Pyin Oo Lwin, Kamamaung and Hpa-an. All collectedmosquitoes were found susceptible to insecticides as recommended by the WHO. Bioefficacy of PermaNet 2.0, DAWA TANA, Yorkool, BASF, Net protect and Yahe LLINs netswere 12(100%), 11/12(91.67%), 4(100%), 8(100%), 5(100%) and 19(100%)respectively. The DAWA TANA net had 20% sensitivity after repetitive washing. Thesensitivity of LLINs nets was higher for all selected areas of States and Regions inMyanmar. The study suggested that there is need to distribute a large number of effectiveLLINs nets in malaria endemic areas as well as the replacement of expired, less effectiveand very old LLINs nets with a new one is also necessary. LLINs nets are very effectiveAnopheles mosquitoes control tools and it can reduce the human-vector contact effectively.Moreover, research on bio-efficacy evaluations of the LLINs nets is required regularly tomaintain and control the transmission of malaria through Anopheles mosquitoes.

A new disubstituted succinate from the roots of Tagetes erecta / 药学学报

Nine compounds were isolated from 95% ethanol extract of the roots of Tagates erecta by silica gel column chromatography and Sephadex LH-20 chromatography. Their structures were identified by spectroscopic data as 5-hydroxymethylfurfuryl methyl succinate (1), 5,7,3'-trihydroxyl-3,6,4'-trimethoxylflavone (2), syringic acid (3), 5,7,4'-trihydroxyl-3,6-trimethoxylflavone (4), patuletin-4'-methoxyl-7-O-β-D-glucopyranoside (5), patulitrin (6), 5,3'-dihydroxyl-3,6,4'-trimethoxylflavone-7-O-β-D-glucopyranoside (7), (2,2'-biththiophen)-5-ol (8), and 3-hydroxyl-4-methoxyl benzoic acid (9). Among them, compound 1 is a new disubstituted succinate and compound 8 was isolated from a natural resource for the first time. Compounds 2, 4, 5 and 9 were isolated from this genus for the first time. By measuring the biological activity and virulence of different compounds against soybean cyst nematode, it has found that compounds 1-8 exhibited a toxic effect on soybean cyst nematode, and ED50 values indicate that compounds 3 and 7 are the most potent, with ED50 values of 0.008 μg·mL-1.

Research progress on chemical constituents and biological activities of Aphanamixis grandifolia / 中草药

Aphanamixis grandifolia, a perennial herb of genus Aphanamixis (Meliaceae), has the effect of relaxing sinew and activating collaterals, dredging arthralgia, expelling wind-evil and removing wetness, etc. Previous phytochemical investigations on this plant resulted in the isolation of various terpenoid derivatives, including limonoids, tirucallane-type, dammarane-type, and cycloartane-type triterpenoids, as well as diterpenoids and sesquiterpenoids. Moreover, bioactivities of those compounds were evaluated, which displayed extensive biological properties, such as antibacterial, insecticidal, antineoplastic, anti-inflammatory, antimalarial, and antibacterial activities, etc. In this paper, the systematic classification, chemical constituents, and biological activities of A. grandifolia were summarized. It may provide the reference for the further studies of this plant.

Insecticidal Efficacy and Chemical Composition of Hexane Oil Extracts from the Leaves of Euphorbia milii and Cassia occidentalis

Insecticidal efficacy of oils from the leaves of Cassia occidentalisand Euphorbia milii on selected insect pests was studied. The oils were extracted via Soxhletapparatus with hexane, and test insects exposed to the oils at 3 dose levels (0.2mg, 0.4mg and 0.6mg) for 24 hours. The results showed contact insecticidal activity of E. miliioil at LD50s and LD90s (mg/kg) as 0.583 and 1.108 for Periplaneta americana, 0.681 and 1.215 for Tettigonia viridissima0.488 and 0.893 for Anopheles gambaie,C. occidentalisoil gave LD50s and LD90s (mg/kg) of 0.889 and 1.689 for P. americana, 1.013 and 1.973 for T. virdissima, and 0.722 and 1.847 for Anopheles gambaie. The corresponding values for the conventional insecticide; SWAN were 0.417 and 1.017 for P. americana, 0.607 and 1.111 for T. viridissimaand 0.40 and 0.743 for A. gambaie,respectively. The GC-MS analysis of plant oils revealed for E.milii,the presenceof hexadecanoic acid, 2 hydroxy-1-(hydroxymethyl) ethyl ester; 6, 9,12,15-docosatetraenic acid methyl ester. For C. occidentalis,the presence of:phthalic acid isobutyl octyl ester; hexadecanoic acid methyl ester; 9,12-octadecadienoic acid methyl ester; 9-octadecenoic acid (z)-methyl ester; methyl stearate; phthalic acid,2-ethylhexyl isohexyl ester; decane; oleic acid; 4,7,-methano-1h-indene,3a,4,7,7a-tetrahydro and n-hexadecanoic acid were revealed. Overall, data from this study provides strong evidence that these oils possess bioactive metabolites with commendable degrees of insecticidal efficacy.

Insecticidal Potentials and Chemical Composition of Essential Oils from the Leaves of Phyllanthus amarus and Stachytarpheta cayennensis in Nigeria

This research evaluated the insecticidal efficacy of essential oils from the leaves of Phyllanthus amarusand Stachytarpheta cayennensison Periplaneta americana (American cockroach), Schistocerca americana(American grasshopper) and Anopheles gambiae (African malaria mosquito). A gas chromatography-Mass spectrometry (GC-MS) analysis of essential oils was also carried out to determine the active components of the oil likely responsible for the observed Insecticidal properties. Insects were exposed to 0.5g of essential oils as well as the positive control (Raid) for 24 hours and mortality observed and recorded every 4 hours. Both essential oils caused 100% mortality in test insects at different time intervals. P.amarusand S.cayennensiscaused 60% and 73% mortality in A.gambiaeat 8hours, 60% and 90% mortality in P.americanaat 12 hours and 40% and 90% mortality in Schistocerca americanaat 16hours. In all cases, S. americanarecorded the least mortality among the test insects as compared to the other insects. S.cayennensisoil proved to be more potent than P.amarusoil. The result of the GC-MS analysis carried out on essential oils from both plants revealed the presence of; Decanoic acid, ethylester(Ethyl decanoate) 6.02%, Dodecanoic acid, ethylester (Ethyl dodecanoate) 11.26%, Tetradecanoic acid, ethylester (Ethyl tetradecanoate) 9.22%, Hexadecanoic acid, ethylester (Ethyl hexadecanoate) 10.16%, Phytol 28.52%, 9, 12, 15-Octadecatrienoic acid, rthylester (Ethyl linolenate) 11.34%, Stigmasta-7,25-dien 3-ol 7.95% and Decanoic acid, ethyl ester (Ethyl decanoate) 6.05%, Dodecanoic acid, ethyl ester (Ethyl dodecanoate) 10.89%, Tetradecanoic acid, ethyl ester (Ethyl tetradecanoate) 8.32%, Hexadecanoic acid ethyl ester (Ethyl palmitate) 5.01%, Phytol 8.27%, Linoleic acid, ethyl ester (Ethyl linolenate) 5.79%, 9,12,15-octadecatrienoic acid, ethyl ester (Ethyl linolenate) 5.79%, Vitamin E 8.29%, Stigmasterol 9.38% and beta-Sitosterol 16.67% for S.cayannensis and P.amarusrespectively. The result from this study indicates that essential oils from these two plants contain potent insecticidal agents that are available, affordable, and effective in the control of insect pests as against the toxic synthetic chemicals currently in use.

Synthesis of new α-amino nitriles with insecticidal action on Aedes aegypti (Diptera: Culicidae)

Abstract Aedes aegypti is the principal vector of arboviral pathogens that may cause diseases as dengue fever, chikungunya and zika. The harmful environmental effects of commercial pesticides coalesced with the development of insecticide-resistant populations encourage the discovery and generation of new alternative products as a tool to reduce the incidence of vector-borne diseases. In this work, through the classic three component Strecker reaction of commercial benzaldehydes, cyclic secondary amines and KCN, a new series of nine α-amino nitriles, girgensohnine analogs, has been synthetized and screened for larvicide and adulticide properties against A. aegypti, one of the dominant vectors of dengue, chikungunya and zika in tropical and subtropical areas all over the world. Molecules 3 and 4 were identified as potential larvicidal agents with LC50 values of 50.55 and 69.59 ppm, respectively. Molecule 3 showed 100% of mortality after 2 h of treatment when a concentration of 30 ppm in adulticidal assays was evaluated. Additionally, in order to elucidate the mode of action of these molecules, their acetylcholinesterase (AChE) inhibitory properties were evaluated using the Ellman assay. It was found that the molecules possess a weak AChE inhibitory activity with IC50 values between 148.80 and 259.40 µM, indicating that AChE could not be a principal target for insecticide activity.

Formulation of Insecticidal Nematode

Insecticidal nematodes or entomopathogenic nematodes (EPNs) in the genera Heterorhabditis and Steinernema are lethal obligate parasites of insect pests. These nematodes carry specific pathogenic bacteria which are released into the insect hemocoel after penetration of the insect host. The economic importance of entomopathogenic nematodes (EPNs) is increasing as the nematodes are amenable for mass production, formulation, handling and application on a large scale and is currently marketed worldwide for use. The objective of the review is to discuss the principles of formulation and quality control, latest development and future perspectives of the EPNs formulation for the successful use of EPNs as bio insecticides.

Larvicidal activity of Neem oil and three plant essential oils from Senegal against Chrysodeixis chalcites (Esper, 1789)

Objective: To evaluate the insecticide, larvicidal and repellent activity of the essential oils from Callistemon viminalis, Melaleuca leucadendron, and Hyptis suaveolens against Chrysodeixis chalcites and to compare it with neem oil (Azadirachta indica). Methods: The essential oils of the leaves of these aromatiques plants were extracted by steam distillation and contacts tests were carried out. Results: Essential oils in ethanol from Callistemon viminalis showed a higher biological activity than the neem with 100% larval mortality at the concentration of 2 μg/mL for 6 h, 100% and 90% in ethanol from Melaleuca leucadendron and Hyptis suaveolens, respectively at the concentration of 4 μg/mL for 24 h. By inhalation, the essential oils from Melaleuca leucadendron and of Hyptis suaveolens were more effective with mortality rates of larvae 100% and 50% respectively at 2 μg/L air applied after 24 h. Nevertheless, the neem has shown to be a repulsive plant and anti-nutritional plant. A significant difference in the percentages of consumption between leaves treated with neem oil and the control samples was observed (Newman-Keuls test) except for Melaleuca leucadendron. Conclusions: The results of the study highlight remarkable biocide, properties of tested extracts, which provides important opportunities for the development of biopesticides.

Protection effect of the anthraquinones, cassiatorin and aurantio-obtusin from seeds of Senna tora against cowpea weevil attack

Objective: To explore the potential insecticidal, ovipositor deterrent and antifeedant effects of ethyl acetate extract of the seeds of Senna tora (Syn. Cassia tora) against cowpea weevil (Callosobruchus maculatus). Methods: The activities were evaluated using standard protocols. In these bioassays, the cowpea seeds were used directly as an insect feed. The activity of the extract and isolated compounds were tested at concentrations of 100, 200 and 300 μg/mL and compared to neem oil and cinnamaldehyde (as standard positive controls). Phytochemical analysis of the ethyl acetate extract was done through a number of chromatographic techniques and the structures of the isolated compounds were established through comprehensive spectroscopic analysis including 2D-NMR and ESI-MS studies. Results: Fractionation of the active ethyl acetate extract resulted in the isolation of one known anthraquinone, aurantio-obtusin (1) and a novel compound that was named as cassiatorin (2). Compounds 1 and 2 showed comparable insect antifeedant properties with the positive controls while their insecticidal and ovipositor deterrent effects were far superior to the standard controls. Conclusions: It is thus concluded that Senna tora extracts and the isolated compounds (1 and 2) may be employed in the postharvest management of stored cowpea seeds and as other crop protectants.

Protection effect of the anthraquinones, cassiatorin and aurantio-obtusin from seeds of Senna tora against cowpea weevil attack

Objective:To explore the potential insecticidal,ovipositor deterrent and antifeedant effects of ethyl acetate extract of the seeds of Senna tora (Syn.Cassia tora) against cowpea weevil (Callosobruchus maculaws).Methods:The activities were evaluated using standard protocols.In these bioassays,the cowpea seeds were used directly as an insect feed.The activity of the extract and isolated compounds were tested at concentrations of 100,200 and 300 μg/mL and compared to neem oil and cinnamaldehyde (as standard positive controls).Phytochemical analysis of the ethyl acetate extract was done through a number of chromatographic techniques and the structures of the isolated compounds were established through comprehensive spectroscopic analysis including 2D-NMR and ESI-MS studies.Results:Fractionation of the active ethyl acetate extract resulted in the isolation of one known anthraquinone,aurantio-obtusin (1) and a novel compound that was named as cassiatorin (2).Compounds 1 and 2 showed comparable insect antifeedant properties with the positive controls while their insecticidal and ovipositor deterrent effects were far superior to the standard controls.Contusions:It is thus concluded that Senna tora extracts and the isolated compounds (1 and 2) may be employed in the postharvest management of stored cowpea seeds and as other crop protectants.

Larvicidal activity of Neem oil and three plant essential oils from Senegal against Chrysodeixis chalcites (Esper, 1789)

Objective:To evaluate the insecticide,larvicidal and repellent activity of the essential oils from Callistemon vimindis,Melaleuca leueadendron,and Hyptis suaveolens against Chrysodeixischalcites and to compare it with neem oil (Azadirachta indica).Methods:The essential oils of the leaves of these aromatiques plants were extracted by steam distillation and contacts tests were carried out.Results:Essential oils in ethanol from Callistemon viminalis showed a higher biological activity than the neem with 100％ larval mortality at the concentration of 2 μg/mL for 6 h,100％ and 90％ in ethanol from Melaleuca leucadendron and Hyptis suaveolens,respectively at the concentration of 4 μg/mL for 24 h.By inhalation,the essential oils from Melaleuca leucadendron and of Hyptis suaveolens were more effective with mortality rates of larvae 100％ and 50％ respectively at 2 μg/L air applied after 24 h.Nevertheless,the neem has shown to be a repulsive plant and anti-nutritional plant.A significant difference in the percentages of consumption between leaves treated with neem oil and the control samples was observed (Newman-Keuls test) except for Melaleucaleucadendron.Conclusions:The results of the study highlight remarkable biocide,properties of tested extracts,which provides important opportunities for the development of biopesticides.