Larvacidal Activity Research Articles

An Investigation on Optical, Larvacidal and Cytotoxicity Analysis of Sulfanilic Acid Single Crystal for Optical and Biomedical Applications.

Sulfanilic acid (SFA) crystal is well known as an effective material for photonic, electro-optical, harmonic generating and biomedical applications. A well-known nonlinear optical material, a high-quality SFA single crystal made utilizing the slow evaporation solution method (SEST) is the subject of this article. A 75 days development period yielded a transparent SFA single crystal measuring 5 × 5 × 2 mm3. The grown crystal used for different characterizations like Single crystal XRD used to find out the cell parameters. Fourier transforms infrared utilized to identify the band assignments. UV-Visible analysis used to detect the absorbance of the crystal and it is utilized for optical application. Photoluminescence studies utilized to recognize the excitation and emission of the grown crystal. Fluorescence used for determining the crystallinity and purity of the sample. The quantitative analysis is verified by using Elemental Dispersive Analysis by X-Rays. Scanning Electron Microscopy utilized to identify the structural and morphological characteristics. To the best of our knowledge, this paper is the first to provide the generated crystal that was used to analyze cytotoxicity and larvacidal activity. Assessment of larvicidal activity was used to ascertain the anti-malarial efficacy. We tested the items on MCF7-Human Breast cancer cell line and MCF7 Vero cells using the MTT Assay to identify the molecular basis of their cytotoxicity in vitro. Biological and optical are two areas that could benefit from the created crystal.

Larvacidal Activity of the Mulberry (Morus alba L.) Leaf Extract Against Larvae of Aedes aegypti

Dengue Haemorrhagic Fever (DHF) is one of the major public health problems in Indonesia. As the population density increases, the number of sufferers increases. Aedes aegypti mosquitoes are vectors for the disease. The absence of drugs make the best prevention effort by eradicating mosquito nests, killing larvae and adult mosquitoes. Mulberry leaves (Morus alba L.) may be used as larvacides in the presence of chemical compounds of flavonoids and saponins that inhibit feeding and disrupt the process of insect metabolism. The purpose of this research has to determine the effect of mulberry leaf extract (Morus alba L.), to determine the larvicide effect of mulberry leaf extract (Morus alba L.) and to determine the concentration of mulberry leaf extract (Morus alba L.) which is optimal in killing third instar Aedes aegypti larvae. This research used Randomized Design Group (RDG) method with treatment consisted 4 concentrations (0.25%, 0.5%, 0.75%, and 1%), negative control and positive control (ABATE) with 6 repetitions. The results of probit analysis showed that LC50 values were 1.124% and LC90 was 4.413%. From the one way ANOVA test at each concentration of 0.25%, 0.5%, 0.75%, and 1%, the F count result is 208.331, the value was greater than F table which is 2.53 and the significant value is 0.000 (sig <0.05) then mulberry leaf extract (Morus alba L.) has a affected to eliminated of Aedes aegypti larvae. Conclusion from the results of the one way ANOVA test of mulberry leaf extract (Morus alba L.) was affected to eliminated third instar Aedes aegypti larvae

A Novel Approach of Chitosan and Its Derivatives Bioactivity Against The Pinworm Tuta absoluta Meyrick (Lepidoptera: Gelechiidae) مقاربة جديدة للنشاط الحيوي للشيتوزان ومشتقاته ضد الدودة الدبوسية توتا أبسلوتا

The present study was carried out to evaluate the relative insecticidal and biological activity of chitosan and its derivativesagainst the 2nd larval instar of T. absoluta compared to the unprecedented insecticide chloroanatrilprole (Coragen) using standardized method of bioassay under laboratory conditions. The larvacidal activity for the different treatments against 2nd instar larvae of T. absoluta were predestined. Also, effect of the tested agents on growth inhibition, antifeedant and life-cycle of the tested insect were determined. The results revealed that chitosan nanoparticles (NPs) was the most effective treatment against 2nd larval instar and eggs deposited per gravid female of T. absoluta. while, chitosan hydroxyapatite nanoparticles (NPs) was the highest effective treatment on growth inhibition and antifeedant. All tested agents disrupted life cycle of the tested insect under laboratory conditions. Therefore, this study suggests the possible using of chitosan and its derivativesas safe alternatives to conventional insecticide and compatible with integrated pest management practices.

Toxicity of essential oils from orange (Citrus sinesis L. Obbeck) and lemongrass (Cymbopogon nardus L. Rendle) on Aedes aegypti a vector of Dengue Hemorrhagic Fever (DHF)

Aedes aegypti mosquito is one of common vectors for the pathogens of different diseases like dengue hemmorrhagic fever. The most common approach to vector-borne disease is by chemical control, mostly through the use of insecticides. As compared to synthetic pesticides, essential oils (EOs) are ecologically safe, have no mammalian toxicity or the chances of development of resistance are reasonable and highly popular with the organic growers. This research has studied the larvacidal activity of essential oil from orange (Citrus sinesis L. Obbeck) and lemongrass (Cymbopogon nardus L. Rendle). Orange and lemongrass cleaned and cut into small pieces, dried and then blended to obtain crude drug samples. Samples distilled with the Stahl distillation method for 4 hours. Furthermore, terpenoids phytochemical test and test against larvae of Aedes aegypti larvicides to obtain the LC50 value. The yield of essential oil of orange (Citrus sinensis L Obbeck) obtained is 6.84%, while the essential oils of lemongrass (Cymbopogon nardus L. Rendle) was 0.96%. In the phytochemical test essential oils either of orange peel and lemongrass showed terpenoids. From the GCMS data, an essential oil from orange and lemongrass contain citronellal and limonene. Citronellal compound acts as an insecticide ingredient that works as an antifeedant and repellent. An essential oil from orange and lemongrass are toxic, with LC50 values obtained from lemongrass 35.133 ppm is smaller than the orange is 790.935 ppm. The essential oil of lemongrass more toxic than the essential oil of orange. Both of essential oils can be used as a green pesticide candidates.

Syzygium Polyanthum Wight Leaf Extract Evaluation On Aedes Spp Instar III-IV Larvae

Aedes spp mosquitos are the vectors that most cause diseases. The rise of insecticide resistance is related to the increasing of vectorial capacity. Plant can be used as an alternative source for controlling these vectors, one of which is Syzygyium polyanthum (Wight). The present study was conducted to investigate the larvasidal properties of S. polyanthum leaf on Aedes spp instar III-IV. Ethanolic extract of S. polyanthum (EESP) was prepared by maceration using ethanol 70%. Larvae were divided into 7 groups (n=25, respectively). Group I to V consisted of different concentrations of EESP (100 (CI);150 (CII);200 (CIII);250 (CIV);300ppm (CV)); VI: Water (W) and VII : Temephos 1% (T). Larvacidal activity was evaluated by calculating the dead larva at 180. 360, 1440 and 2880 minutes to obtain Lethal Concentration 50% (LC50) and Lethal Time 50% (LT50) using Statistical Product and Service Solution (SPSS). The result showed that no larva found dead in W-treated group. Otherwise, the mortality of larva was increased with increasing of EESP concentration (CI to CV). LC50 and LT50 showed 213 ppm and 2410 minutes, respectively. We conclude that EESP has larvicidal activity on Aedes spp instar III-IV.
 Keywords: Aedes spp, extract, larvicidal, Syzygium polyanthum

Sand Granules Ekstrak Biji Alpukat (Persea Americana Seed Extract) sebagai Larvasida Alami Pemberantas Demam Berdarah Dengue

Dengue hemorrhagic fever (DHF) threatens people in the rainy season. DHF is one of the major public health problems in Indonesia. These problems encourage an effort to eradicate Ae. aegypti larvae by using natural larvicide. One of the plants that can be used as natural larvicides is avocado seeds (Persea americana Seed) which contain saponin. This study aims to determine the larvacidal activity of avocado seed extract sandgranules with LC50 of 8.87 mg.mL-1 against Ae. aegypti larvae. This study is an experimental research with a complete random design in a unidirectional pattern. The independent variable in this study is the variation concentration of Explotab as a disintegrant agent ie 2, 3, and 4%. Sand granules of avocado seed extract are made by wet granulation method. Results of the larvacidal activity test of avocado seed extract sand granules were analyzed by calculating the percentage of larvae mortality and statistical analysis using SPSS. The results of this study is the larvacidal activity of pure avocado seed extract with LC50 8.87 mg. L-1 is greater than the avocado seed extract sand granules. The addition of Explotab did not affect the total larvae mortality, but there was a significant difference in larvae mortality at 5 hours of sand granules exposure with explotab concentration of 3% and 4% (a significance value <0.05).

Synthesis and insecticidal activity studies of novel phenylpyrazole derivatives containing arylimine or carbimidate moiety

Phenylpyrazole insecticides are successful for crop protection and public hygiene by blocking gamma-aminobutyric acid (GABA)-gated chloride channels and glutamate-gated chloride (GluCl) channels. A series of novel phenylpyrazoles containing arylimine or 1-methoxyaryl groups were designed and synthesized. The addition reaction of methanol to the imines 1–11 was investigated and the cayno addition products 13–15 were obtained. The compounds 1–15 were confirmed by 1H NMR and elemental analysis. The results of bioassay indicated that some compounds exhibited comparable bioactivity to fipronil against a broad spectrum of insects such as bean aphid (Aphis craccivora), mosquito (Culex pipiens pallens), diamondback moth (Plutella xylostella) and Oriental armyworm (Mythimna separata). Especially, the foliar contact activity against bean aphid of compound 7 at 10 µg mL−1 was 68%, the larvacidal activity against mosquito of compounds 5, 13 and 15 at 0.0025 µg mL−1 was 100%, the larvacidal activity against diamondback moth of compounds 9 and 11 at 0.05 µg mL−1 was 100%, the larvacidal activity against Oriental armyworm of compound 9 at 1 µg mL−1 was 100%. The 3-cayno moiety on pyrazole ring was essential for the high insecticidal activities against bean aphid, diamondback moth and Oriental armyworm, while the 3-carbimidate moiety on pyrazole ring was crucial to the excellent high insecticidal activities against mosquito.

Adulticide Efficacy of Artemisia vulgaris L. against Aedes aegypti L.

Aedes aegypti is the vector of various arthropod-borne diseases such as dengue fever, chikungunya and currently, zika. This study aimed to evaluate Artemisia vulgarisas other adulticides for controlling Ae. aegypti. Indonesian ministry of health hasbeen reported that more than 70.000 dengue fever human cases have occurred in 2015 covering 34 provinces which mean that dengue fever has spread now into all national territories. Eradication of Aedes still largely depends on insecticides, which is the most cost-effective strategy, and often inefficient due to resistance development in exposed Aedes population This study was designed to use of Centers for Disease Control and Prevention (CDC) bioassay standard. CDC bottles were coated with the ethanolic solution of extract with a concentration of 10, 50, 100, 500, 1000, 5000, 10000, 50000, and 100000 g per bottle. F0 mosquitoes were used for all experiments. Death and surviving mosquitoes were evaluated based on CDC standard assay. The test was performed with 10-25 adult mosquitoes every bottle and each concentration was repeated in triplicates. The results showed that LC50 and LC90 were 5790 g and 52110 g respectively after 120 minutes exposure to the extract. There was no mortality in ethanol control group. A. vulgaris significantly (P < 0.05) have adulticidal activity against Ae. aegypti. However, A. vulgaris have been reported to have larvacidal activity against Ae. Aegypti. These results indicated clearly that A. Vulgaris might act as the candidate of bioinsecticides for controlling Ae. aegypti. Keywords: Aedes aegypti, Artemisia vulgaris, adulticide,bio insecticide.

Evaluation of Larvacidal Activity of Olea europaea Extract against Anopheles Mosquito in In vitro, Fogera Woreda, North Western Ethiopia

Mosquitoes are the major public health threat as they are the vectors of malaria. Since mosquitoes developed resistances towards chemical insecticides, researchers are searching for alternative control measures. Secondary metabolites and bioactive chemicals present in plants serve as a defense mechanism against insects’ larvae. Therefore, the aim of this study was to evaluate larvacidal activities of Olea europaea (O. europaea) extracts In vitro against 3rd-4th instars larvae of Anopheles arabiensis. The fresh leaves of the plant were collected from Fogera Woreda and brought to Bahir Dar University to be extracted by petroleum ether, chloroform, acetone and ethanol. The extract was filtrated using Buchner funnel with Whatman filter paper; undergone rotary evaporator and stored at -4 C until larvicidal bioassay test. Furthermore, the phytochemical screening was carried out and appropriate solution was prepared. Larvae of A. arabiensis were collected from Woreta town and bioassay was performed on 20 larvae at room temperature. The percentage mortality at 24, 48 and 72 hours was computed. The result showed that petroleum ether, chloroform, acetone and ethanol extracts of O. europaea has resulted in significant mortality of larvae (P=0.00). All solvent extracts showed increased mortality rate with time and concentrations. Based on the current result, we recommend that further studies are needed to characterize active ingredients of screened phytochemicals and evaluate their toxicity, and to study their impacts on human health and non-target organisms in mosquito habitats.

Dengue Hemorrhagic Fever: Past, Present, and Future

Abstract: Dengue viral infection is a global disease with a spectrum of clinical manifestations mild fever to severe disease both dengue hemorrhagic fever (DHF) and dengue shock syndrome (DSS). DHF is severe form of dengue fever (DF), which can be life-threatening. Climate changes is not the only factor that affects dengue transmission, but also globalization changes includes travel and trade. The pathogenesis of dengue infection is complex. The mechanism involved antibody-dependent enhancement, NS1 and its antibodies, T cells, and DENV genomics. There are several novel methods to detect the presence of dengue virus in the body of infected patients. These include ELISA-specific IgM and IgG detection, detection of monoclonal antibodies and mosquito cell strains, and PCR reverse transcriptase detection. Several trials found novel methods to predict the severity of dengue hemorrhagic fever earlier. These include platelet count, Aspartate aminotransferase / platelet count index (APRI) Index, serum chymase level, serum cytokine/chemokine profile, Tropomyosin-alpha 1 (TPM 1), Reticulocyte Production Index (RPI), and Immature Platelet Fraction (IPF). Several pharmacological therapies are known to have potential antidengue effect. Some of these are corticosteroids, antimalarial drugs, doxycycline and tetracycline, anticholesterol drugs, IVIG, celgosivir, balapiravir, pentoxifylline and calcium supplementation. Some natural products are known to have activity against Aedes aegypti through antiviral mechanisms, larvacidal activity, mosquitocidal, and mosquito repellants. It can be developed as the latest therapy of dengue hemorrhagic fever on the future. The objective of this paper is to provide new insight about the development of dengue hemorrhagic fever related to the history of its distribution, pathogenesis, and the latest developments related to detection methods, severity prediction methods, and the management of dengue hemorrhagic fever on the future. Keywords: globalization changes, novel detection methods, severity prediction methods, latest development in DHF therapy

Phenolic composition, antioxidant, antibacterial, larvacidal against Culex pipiens, and cytotoxic activities of Hyacinthella lineata steudel extracts

ABSTRACTThis study reports the phenolic composition, antioxidant, antibacterial, larvacidal, and cytotoxic activity of methanol and acetone extracts of Hyacinthella lineata leaves and bulbs. The phenolic composition of H. lineata was determined by HPLC. The most abundant component was gallic acid (421.9µg/g). The β-carotene/DPPH/ABTS/FRAP decoloration method was used to estimate the total antioxidant activity. The total antioxidant activity was the highest for bulb-methanol fraction (65.41 ± 0.05%). The total phenolic content for leaves-methanol extract of the plant was determined as 6.56 ± 4.027mg/mL gallic acid equivalents. Analysis of the antibacterial activity showed that the methanolic-bulb extract are efficient against gram positive and gram negative bacteria. The cytotoxic effect on Artemia salina was assessed by Brine shrimp assay. Brine shrimp lethality assay showed that LC50 values of HBM were obtained as 4.105 ± 2.42μg/ml. The bulb extract of H. lineata showed the highest larvicidal activity against Cx pipiens with value LC50 (64.3275μg/ml). This study suggested that H. lineata may be used as a potential source of antioxidant, and for their biological activity, cytotoxic and antimicrobial properties.

New Bioinsecticide Granules Toxin from Ectract of Papaya (Carica Papaya) Seed and Leaf Modified Against Aedes Aegypti Larvae

The epidemic of dengue hemorrhagic fever (DBD) in Indonesia, which occurs every year, has become a problem for the Indonesian society. Aedes aegypti mosquito is a vector of this disease. During this time the larvae of Aedes aegypti only has one exterminator is abate. In the long time exposure of single type insecticide will cause resistance. Therefore, it is necessary to find new bioinsectiside which is expected to have effects such as abate. The aims of this study are to offer technology, dosage, formulation and toxicity of new bioinsecticide granules toxin from ectract of papaya (Carica papaya) seed and leaf modified against Aedes aegypti larvae. Methodpreparation of the extract by percolation method with 70% ethanol for seeds, and with water-ethanol 70% for leaf. Bioassay with active ingredients with thin layer chromatography. Formulation for 300g Granules are: active substances papaya seed and leaf modified: 90%, seed flour 5%, filler: 5%. This was an experiment using a completely randomized design with 6 treatment groups. Each group contained 20 third instar larvae of Aedes aegypti. Concentrations of granules are 0, 30, 60, 90. 120, 150ppm, with Temephos 1% as a positive control. Data was analyzed using Probit analysis. ResultsThe result of phytochemical analysis contains secondary metabolites compounds of saponin, flavonoid and triterpenoid. Toxicity (LC50) in this study is reported 107ppm; 48hours and LC90: 150ppm, 48hours. ConclusionNew Bioinsecticide Granules Toxin from extract of Papaya (Carica papaya) Seed and leaf Modified Against Aedes aegypti larvae possess technology, dosage, formulation, and larvicidal remarkable. Further investigations are needed to elucidate active ingredient responsible for larvacidal activity should be identified and utilized in preparing a commercial product.

Synthesis and larvicidal and adult topical activity of some hydrazidehydrazone derivatives against Aedes aegypti

A series of novel hydrazide-hydrazone derivatives were synthesized and evaluated for their larvicidal and adult topical activity against Aedes aegypti. The proposed structures of all the synthesized compounds were confirmed using elemental analysis, UV, IR, 1 H-NMR, 13 C-NMR and mass spectroscopy. Compounds 4a-h were screened in larval bioassays at concentrations of 100, 50 and 25 ppm in a dose dependent manner and data for their mortality was recorded. Among the tested compounds, 1-(4-nitrophenyl)-3-(4-{2oxo-2-[2-(2-oxo-1,2-dihydro-3H-ylidene)hydrazinyl] ethyl} phenyl)urea (4b) showed noteworthy larvacidal activity against Aedes aegypti. Dose-response data of compound 4b showed LC 50 and LC 90 values of 30.5 (15.4 – 22.7) and 95.9 (73.8 – 139.4) ppm, respectively. Screening of compounds 4a-h at four doses by topical bioassay indicated a range of activity between 10000 and 1000 ppm.

Antimicrobial, phytochemical and larvicidal properties of Jatropha multifida Linn.

ObjectiveTo evaluate the phytochemical, antimicrobial and insecticidal properties of different extracts of Jatropha multifida (J. multifida) in Mauritius. MethodsQualitative and quantitative methods were used for the determination of the presence of phytochemicals in the crude solvent extracts of J. multifida. The antimicrobial sensitivity (disc diffusion method) and antibacterial activity (microdilution method) of 13 microorganisms were reported. The insecticidal properties of the crude solvent extracts were tested against the larvae of two insects, Bactrocera zonata and Bactrocera cucurbitae (Diptera: Tephritidae), which cause important economic losses to local fruits. ResultsEthyl acetate was proved to be a good solvent for extraction. J. multifida showed very interesting activity against Bacillus algicola and Staphylococcus epidermis. The plant also showed good larvacidal activity against Bactrocera zonata. ConclusionsThis paper reports the dual use of J. multifida, hence further studies can be made in term of application.

English

The bacterial isolate Serratia entomophila AB2 having multidimensional attributes like larvacidal activity and nutrient-solubilizing capability was used to test its effect on productivity of groundnut. Two different inorganic carriers (talcum powder and vermiculite) based formulations of the bacterial isolate were also tested along with the unformulated product and 100% recommended dose of NPK (60:60:50) for comparative study. S. entomophila AB2 (unformulated) efficiently minimized lepidopteran pest infestations when compared with control (larval stage of Heliothis armigera, 27%; Spodoptera litura, 30%; Plutella xylostella, 23%). The strain also increased seed germination by 10%, increment in shoot weight was by 100% and enhancement of seed weight was by 120% in comparison to negative control in a field trial. But, both of the inorganic carrier based formulations showed better results in respect to pest control and productivity compared to the unformulated bacterium. Among the two formulations used in this study, vermiculite based formulation was found effective in terms of pest control and productivity. Consequently, a vermiculite based formulation of S. entomophila AB2 could be effectively used at the rate of 3.6 qthec-1 for quality and yield enhancement of groundnut. Key words: Serratia entomophila AB2, fermentation, pesticide, nutrient solubilizer, integrated crop management (ICM) productivity.

Efficacy of entomopathogenic nematodes (Rhabditida: Heterorhabditidae and Steinernematidae) against codling moth, Cydia pomonella (Lepidoptera: Tortricidae) in temperate regions

The biocontrol potential of South African isolates of Heterorhabditis zealandica, Steinernema citrae, S. khoisanae, S. yirgalemense, and Steinernema sp., was evaluated against codling moth, Cydia pomonella. Codling moth was susceptible to all six nematode isolates at a concentration of 50 infective juveniles/insect (78–100% mortality). Low temperatures (10 h at 17°C; 14 h at 12°C) negatively affected larvicidal activity (≤3%) for all isolates. All tested isolates were most effective at higher levels of water activity (a w=1). The average a w50-values for all isolates tested was 0.94 (0.93–0.95), except S. khoisanae 0.97 (0.97–0.98). Regarding host-seeking ability, no positive attraction to host cues could be detected amongst isolates, except for H. zealandica. Three of the isolates, H. zealandica, S. khoisanae, and the undescribed Steinernema sp., were selected for field-testing and proven to be effective (mortality >50%). Insect containment methods used during field experimentation was shown to influence larvacidal activity, as different levels of mortality were obtained using various containment methods (wooden planks vs. pear tree logs vs. mesh cages). Pear tree logs were impractical. Predictive equations were subsequently developed, enabling future trials to be conducted using either planks or cages, enabling the prediction of the expected level of control on tree logs. All tested isolates therefore showed a certain degree of biological control potential, however, none of the experiments showed clear efficacy-differences amongst isolates. The study highlighted the importance of environmental factors to ensure the successful application of these nematodes for the control of diapausing codling moth larvae in temperate regions.

Antifungal and Insecticide Activities of Twenty Three Spices Against Plant Pathogens

There has been recent interest in research concerning the possible use of natural plant extracts for pest management as alternatives to synthetic agrochemicals that are safer for human health and the environment. In this respect, 23 common spices were evaluated for antifungal activity against three Colletotrichum species using direct-bioautography assays. Turmeric, nutmeg, ginger, clove, oregano, black paper, fennel and anise showed promising antifungal activity against C. acutatum, C. fragariae, and C. gloeosporioides. Antifungal activity was indicated by the presence of clear inhibitory zones appearing against a dark background of fungal growth on the TLC plate. These clear zones represented regions where fungal mycelia or reproductive stroma were not present. Through the Deployed War-Fighter Protection (DWFP) Research Program we have expanded our role in exploration and identification of new natural compounds for insecticidal and mosquito deterrent activity. The twenty-three plant extracts were also evaluated for mosquito larvacidal, adulticidal, and repellent activity against Aedes aegypti. Pest management results will be present in the poster.

UJI LARVASIDA NYAMUK (Aedes aegypti) DARI ASCIDIAN (Didemnum molle)

Dengue haemorrhagie fever is one of the disease which caused by dengue virus. It spreads out by mosquito Aedes aegypti as the vector. To date, people use abate as the larvacidal. Yet it causes the negative effects, such as bad odor, rustiness of the water container and resistency either to the larvae or to the living environment if continue using it. The objective of the research was to examine the larvacidal activity of Didemnum molle extract against A. aegypti larvae. The sample was extracted with methanol to give methanolic extract which was further partitioned with ethyl acetate, hexane, and chloroform to yield three fractions of ethyl acetate, hexane, and chloroform. Methanolic extract and the three fractions were tested against the A. aegypti larvae instar III for several concentrations. Abate and tap water were used as controls. The result exhibited that Didemnum molle extracts contain or produce larvacidae substances against A. aegypti larvae. They are approved by the data of methanolic extract and the 3 fractions which are more powerful than abate, particularly hexane. However it still needs to be purified to obtain single active compound.

Design, Synthesis and Insecticidal Activity of Novel Phenylpyrazoles Containing a 2,2,2-Trichloro-1-alkoxyethyl Moiety

A series of novel phenylpyrazoles containing a 2,2,2-trichloro-1-alkoxyethyl moiety were designed and synthesized via the key intermediate 5-trichloroethylideneimino-3-cyano-1-(2,6-dichloro-4-trifluoromethylphenyl)-4-alkylsulfenylpyrazole (5). The addition reaction of the imine 5 was closely related with the nature of the alcohol. The target compounds were confirmed by (1)H NMR and elemental analysis. The results of bioassays indicated that the target compounds possessed excellent activities against a broad spectrum of insects such as bean aphid (Aphis craccivora), mosquito (Culex pipiens pallens) and diamondback moth (Plutella xylostella). Especially, the foliar contact activity against bean aphid of compound 7h at 2.5 mg kg(-1) was 89%, the larvacidal activity against mosquito of compound 6c at 2.5 microg kg(-1) was 100%, the activity against diamondback moth of compound 7a at 5 mg kg(-1) was 87%, and all of these activities were much higher than the contrast ethiprole. The results of insecticidal activities showed that the two pairs of enantiomers 7d-1 and 7d-2 gave activities without distinctive difference, and it was the similar situation for 7e-1 and 7e-2. Interestingly, the target compounds exhibited high selectivity between diamondback moth and oriental armyworm, both of which are of the order Lepidoptera. The 2,2,2-trichloro-1-alkoxyethyl moiety was essential for high insecticidal activities.

Synthesis and Insecticidal Activities of Novel N-Sulfenyl-N′-tert-butyl-N,N′-diacylhydrazines. 1. N-Alkoxysulfenate Derivatives

A series of novel N-alkoxysulfenyl-N'-tert-butyl-N, N'-diacylhydrazines were designed and synthesized as insect growth regulators by the key intermediates N-chlorosulfenyl-N'-tert-butyl-N, N'-diacylhydrazines, which were prepared for the first time. Compared to N'-tert-butyl-N, N'-diacylhydrazines, these N-alkoxysulfenyl derivatives displayed better solubility and improved hydrophobicities. The insecticidal activities of the new compounds were evaluated. The results of bioassays showed that the title compounds possessed a combination of strong stomach as well as contact poison property higher than the corresponding parent compounds. In particular, N-methoxysufenyl-N'-tert-butyl-N-4-ethylbenzoyl-N'-3,5-dimethylbenzoylhydrazide (IIIf) as a field testing candidate has higher stomach toxicities against oriental armyworm and beet armyworm than the corresponding parent compound RH-5992. Furthermore, the compound IIIf exhibits higher contact activities against oriental armyworm, Asian corn borer, tobacco cutworm, and cotton bollworm than RH-5992. The sulfenyl substituent was essential for high larvacidal activity.