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Larvicidal Activity (larvicidal + activity)
Selected AbstractsSynthesis and insecticidal evaluation of novel N-oxalyl derivatives of diacylhydrazines containing methylcarbamate moietiesHETEROATOM CHEMISTRY, Issue 6 2005Chunhui Mao A series of new N -oxalyl derivatives of diacylhydrazines containing methylcarbamate moieties were synthesized by the reaction of N -oxalyl chloride of N -methylcarbmates with N - tert -butyl- N,N,-diacylhydrazines in the presence of sodium hydride. The reaction of oxalyl chloride with N - tert -butyl- N, N,-diacylhydrazines to yield 1,3,4-oxadiazole and 4- tert -butyl-2-substituted-phenyl-4H -1,3,4-oxadiazine-5,6-dione was found, and the reaction was studied in some detail. The title compounds were evaluated for molting hormone mimicking activity. The results of bioassay showed that the title compounds exhibit moderate larvicidal activities, and toxicity assays indicated that these compounds can induce a premature, abnormal, and lethal larval molt. © 2005 Wiley Periodicals, Inc. Heteroatom Chem 16:472,475, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.20135 [source] Structure,Activity Relationship Studies on Derivatives of Eudesmanolides from Inula helenium as Toxicants against Aedes aegypti Larvae and AdultsCHEMISTRY & BIODIVERSITY, Issue 7 2010Charles Abstract An Aedes aegypti larval toxicity bioassay was performed on compounds representing many classes of natural compounds including polyacetylenes, phytosterols, flavonoids, sesquiterpenoids, and triterpenoids. Among these compounds, two eudesmanolides, alantolactone, and isoalantolactone showed larvicidal activities against Ae. aegypti and, therefore, were chosen for further structure,activity relationship study. In this study, structural modifications were performed on both alantolactone and isoalantolactone in an effort to understand the functional groups necessary for maintaining and/or increasing its activity, and to possibly lead to more effective insect-control agents. All parent compounds and synthetic modification reaction products were evaluated for their toxic activities against Ae. aegypti larvae and adults. Structure modifications included epoxidations, reductions, catalytic hydrogenations, and Michael additions to the ,,, -unsaturated lactones. None of the synthetic isomers synthesized and screened against Ae. aegypti larvae were more active than isoalantolactone itself which had an LC50 value of 10.0,,g/ml. This was not the case for analogs of alantolactone for which many of the analogs had larvicidal activities ranging from 12.4 to 69.9,,g/ml. In general, activity trends observed from Ae. aegypti larval screening were not consistent with observations from adulticidal screening. The propylamine Michael addition analog of alantolactone was the most active adulticide synthesized with an LC50 value of 1.07,,g/mosquito. In addition, the crystal structures of both alantolactone and isoalantolactone were determined using CuK, radiation, which allowed their absolute configurations to be determined based on resonant scattering of the light atoms. [source] EVALUATION OF EXTRACTS FROM BAMBOO FOR BIOLOGICAL ACTIVITY AGAINST CULEX PIPIENS PALLENSINSECT SCIENCE, Issue 4 2004Hai-qun Cao Abstract The extracts from 7 species of bamboo were tested for larvicidal activity against Culex pipiens pallens. At the tested concentration, the extracts of selected bamboo had different degree of toxic effects on the fourth instar larvae of Culex pipiens pallens. Among them, the extracts of Pleioblastus juxianensis, Brachystachyum albostriatum, Phyllostachys platyglossa and Pleioblastus amarus were found to be effective with LC50values at 24 h of 30.65 mg/L, 53.94 mg/L, 41.21 mg/L and 54.49 mg/L respectively, against Culex pipiens pallens larvae. The extract of Pleioblastus juxianensis by Soxhlet method showed stronger activity than the extract obtained by interval-shaking, the LC50 of which were 30.65 mg/L and 48.34 mg/L, respectively. The diethyl ether extract of Pleioblastus juxianensis exhibited better larvicidal activity than the methanol extract and the petroleum ether extract. The results would help to provide the basis for the study of environment acceptable pesticide for mosquito control, and also help to comprehensively utilize the source of bamboo. [source] Chitinolytic activities in Bacillus thuringiensis and their synergistic effects on larvicidal activityJOURNAL OF APPLIED MICROBIOLOGY, Issue 3 2002M. Liu Aims: To investigate the distribution of chitinase in Bacillus thuringiensis strains, and the enhancing effects of the chitinase-producing B. thuringiensis strains on insecticidal toxicity of active B. thuringiensis strain against Spodoptera exigua larvae. Methods and Results: The chitinolytic activities of B.thuringiensis strains representing the 70 serotypes were investigated by the whitish opaque halo and the colorimetric method. Thirty-eight strains produced different levels of chitinase at pH 7·0, and so did 17 strains at pH 10·0. The strain T04A001 exhibited the highest production, reaching a specific activity of 355 U ml,1 in liquid medium. SDS-PAGE and Western blotting showed that the chitinase produced by some B. thuringiensis strains had a molecular weight of about 61 kDa. The bioassay results indicated that the chitinase-producing B. thuringiensis strains could enhance the insecticidal activity of B. thuringiensis strain DL5789 against S. exigua larvae, with an enhancing ratio of 2·35-fold. Conclusion: This study demonstrated that chitinase was widely produced in B. thuringiensis strains and some of the strains could enhance the toxicity of active B. thuringiensis strain. Significance and Impact of the Study: This is the first investigation devoted exclusively to analyse the distribution of chitinase in B. thuringiensis. It infers that the chitinase produced by B. thuringiensis might play a role in the activity of the biopesticide. [source] Larvicidal and oviposition-altering activity of monoterpenoids, trans -anithole and rosemary oil to the yellow fever mosquito Aedes aegypti (Diptera: Culicidae),PEST MANAGEMENT SCIENCE (FORMERLY: PESTICIDE SCIENCE), Issue 3 2009Ranil Waliwitiya Abstract BACKGROUND:Aedes aegypti L. is the major vector of dengue fever and dengue hemorrhagic fever. In an effort to find effective tools for control programs to reduce mosquito populations, the authors assessed the acute toxicities of 14 monoterpenoids, trans -anithole and the essential oil of rosemary against different larval stages of Ae. aegypti. The potential for piperonyl butoxide (PBO) to act as a synergist for these compounds to increase larvicidal activity was also examined, and the oviposition response of gravid Ae. aegypti females to substrates containing these compounds was evaluated in behavioral bioassays. RESULTS: Pulegone, thymol, eugenol, trans -anithole, rosemary oil and citronellal showed high larvicidal activity against all larval stages of Ae. aegypti (LC50 values 10.3,40.8 mg L,1). The addition of PBO significantly increased the larvicidal activity of all test compounds (3,250-fold). Eugenol, citronellal, thymol, pulegone, rosemary oil and cymene showed oviposition deterrent and/or repellent activities, while the presence of borneol, camphor and ,-pinene increased the number of eggs laid in test containers. CONCLUSIONS: This study quantified the lethal and sublethal effects of several phytochemical compounds against all larval stages of Aedes aegypti, providing information that ultimately may have potential in mosquito control programs through acute toxicity and/or the ability to alter reproductive behaviors. Copyright © 2008 Society of Chemical Industry [source] Investigation of the larvicidal activity of Pothomorphe peltata and isolation of the active constituentPHYTOTHERAPY RESEARCH, Issue S1 2002Dr E. Mongelli Abstract The insecticidal activity of the leaves of Pothomorphe peltata (Piperaceae) was evaluated on Aedes aegypti larvae. The active methanol extract was subjected to a bioactivity-directed fractionation, monitored by the larvicidal assay, and led to the isolation of a catechol derivative, 4-nerolidylcatechol. This compound was quite potent against Aedes aegypti larvae (LC50,=,9.1,µg/mL). Copyright © 2002 John Wiley & Sons, Ltd. [source] Larvicidal Effects of Fungal Meroterpenoids in the Control of Aedes aegypti L., the Main Vector of Dengue and Yellow FeverCHEMISTRY & BIODIVERSITY, Issue 2 2008Regina Geris Abstract The mosquito Aedes aegypti is an increasing problem of public health, being the vector responsible for dengue and Yellow Fever in tropical and subtropical regions. The aim of this work was to determine the potential larvicidal activity of a series of meroterpenoids, compounds 1,7, previously obtained fungal secondary metabolites from Penicillium sp., against the third-instar larvae of A. aegypti. The lethal concentrations (LC50 and LC90) of 1,7 were evaluated 24,h after exposure. Dehydroaustin (4) was the most active meroterpenoid in the series, with an LC50 value of 2.9,ppm, making it an attractive natural insecticide. [source] Synthesis and Bio-activities of Pyrazolyl or Pyridinyl Substituted Tonghaosu AnalogsCHINESE JOURNAL OF CHEMISTRY, Issue 6 2007Biao-Lin Yin Abstract 11 pyrazolyl or pyridinyl substituted tonghaosu analogs were synthesized. Structures of all the new compounds were confirmed by 1H NMR, IR, MS, HREIMS or elemental analysis. Their antifeedant activity against larvae of large white butterfly (Pieris brassicae L.), larvicidal activity toward mosquito (Culex quinquefasciatus Say) and growth control activity toward larvae of Spodoptera litura Fab were examined. Some of them exhibited antifeeding activities comparable to or stronger than tonghaosu Z-1. Based on the activity data, the preliminary structure-activity relationship was also discussed, which might be instructive for finding out lead compounds with better bioactivities in the future. [source] | |||||||||||||