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1.
Permethrin resistance status of a laboratory strain, a permethrin-selected strain and three field strains of Aedes aegypti collected in Kuala Lumpur, Malaysia were evaluated using three standard laboratory bioassays: WHO larval bioassay, WHO adult mosquito bioassay, and mixed function oxidase (MFO) enzyme microassay. The LC50 values of field strains from the WHO larval bioassay did not differ significantly. The highest LC50 value was from the Taman Melati field strain (0.39 mg/L). The resistance ratio for the permethrin-selected strain and the field strains ranged from 1.86 fold to 5.57 fold. Pre-exposure to piperonyl butoxide (PBO) in the WHO adult bioassay and MFOs enzyme microassay reduced the LT50 values and reduced the mean optical density of elevated oxidase activity (0.28–0.42) at 630 nm. The LC50 or LT50 values and the level of oxidases were significantly correlated (r = 0.825; p< 0.05). This study confirmed the presence of permethrin resistance in these mosquito populations.  相似文献   

2.
To develop a less technique-dependent bioassay technique that can be conveniently used by practitioners or farmers in the field for the monitoring of acaricide resistance of the two-spotted spider mite, Tetranychus urticae Koch, a residual contact vial (RCV) method was established using a 5-ml glass vial coated with acaricides. The RCV bioassay procedures were optimized by using abamectin and tebufenpyrad, two widely used acaricides. The diagnostic concentrations causing 100% mortality within 8 h post-treatment in a susceptible strain of T. urticae was set at 30 and 60 ppm for abamectin and tebufenpyrad, respectively. The vial-coated pesticides were stable at least one year when stored at ? 20 °C as determined by HPLC. There was no significant difference in the bioassay results in repeated RCV bioassay by three different experimenters, indicating its high reproducibility and reliability. RCV-based resistance monitoring of 15 field populations of mites revealed that abamectin resistance begins to spread but tebufenpyrad resistance is already prevalent in Korea. The RCV diagnostic kit, when used by practitioners or farmers on site, should provide crucial information for the selection of most suitable acaricides for different field populations of T. urticae.  相似文献   

3.
Acute toxicity tests were carried out to determine the effect of three larvicides, spinosad, pirimiphos methyl, and chlorpyrifos, on Culex quinquefasciatus Say, Anopheles gambiae s.s. Giles (Diptera: Culicidae), and guppies, Poecilia reticulata Peters (Pisces: Poeciliidae). Thereafter, larvae of Cx. quinquefasciatus were introduced to P. reticulata in containers of different volumes with low concentrations of each larvicide at established predator to prey densities of 1–35; 5–70 and 10–350 (fish to larvae) respectively. The experiment was replicated six times, and the larval consumption was counted after 24 h. Spinosad and pirimiphos methyl were significantly toxic to Cx. quinquefasciatus, the less susceptible mosquito species. Guppy consumption of Culex larvae was highest at a predator to prey density 5–70. Feeding activity of guppies increased in the spinosad treatment at 49 μg L−1 compared to control and the synthetic larvicides. The synthetic larvicides generally reduced consumption of larvae except for the lowest concentration of pirimiphos methyl which increased it at the highest predator to prey density in a 3 L container. The highest percentage of Culex larvae was consumed by fish in the presence of spinosad at 49 μg L−1 and a predator to prey density of 5–70 in 0.5 L plastic containers. Thus, predator to prey density, container size, type and concentration of larvicide are all important factors to be considered in integrated management of mosquito larvae.  相似文献   

4.
Series of benzimidazole and benzothiazole linked phosphoramidates and phosphoramidothioates (5aj) and benzimidazole linked phenylphosphoramidates and phenylphosphoramidothioates (10ae) 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.  相似文献   

5.
《Journal of Asia》2014,17(3):327-331
Mosquitoes are major arthropod vectors responsible for several pathogenic diseases. In recent years, repellents of botanical origin, particularly essential oils, have been used against mosquitoes and have been found effective and safe. In this study, five different repellent cream formulations (CF1–5) were prepared using combinations of essential oils, including camphor, cinnamon, citronella, lemongrass, lime, orange, neem, basil, Vitex, Lantana, eucalyptus, and clove, and their repellency was tested using Culex quinquefasciatus Say and Aedes aegypti L. under laboratory conditions and compared to the standard synthetic repellent N,N-diethyl-meta-toluamide (DEET-12%, w/w). Among the five cream formulations, CF2 at a dose of 5 mg/cm2 showed the longest protection time of 4.18 h and 3.31 h against C. quinquefasciatus and A. aegypti, respectively, under laboratory conditions. CF3 at a dose of 5 mg/cm2 was moderately effective, with protection times of 3.42 h and 2.58 h against C. quinquefasciatus and A. aegypti, respectively, under laboratory conditions. CF2 at a dose of 5 mg/cm2 was also tested in the field against wild mosquitoes for 3 h, and 100% protection was observed for the entire study period. Thus, CF2 could be used in developing an effective natural repellent as an alternative to the existing synthetic repellents to C. quinquefasciatus and A. aegypti.  相似文献   

6.
7.
This study investigated the phytochemical, antioxidative, antimicrobial and cytotoxic effects of Leea indica leaf ethanol extract. Phytochemical values namely total phenolic and flavonoid contents, total antioxidant capacity, DPPH radical scavenging effect, FeCl3 reducing power, DMSO superoxide scavenging effect and Iron chelating effects were studied by established methods. Antibacterial, antifungal and cytotoxic effects were screened by disk diffusion technique, food poison technique and brine shrimp bioassay, respectively. Results showed the total phenolic content 24.00 ± 0.81 g GAE/100 g, total flavonoid content 194.68 ± 2.43 g quercetin/100 g and total antioxidant capacity 106.61 ± 1.84 g AA/100 g dry extract. Significant (P < 0.05) IC50 values compared to respective standards were recorded in DPPH radical scavenging (139.83 ± 1.40 μg/ml), FeCl3 reduction (16.48 ± 0.64 μg/ml), DMSO superoxide scavenging (676.08 ± 5.80 μg/ml) and Iron chelating (519.33 ± 16.96 μg/ml) methods. In antibacterial screening, the extract showed significant (P < 0.05) zone of inhibitions compared to positive controls Ampicillin and Tetracycline against Gram positive Bacillus subtilis, Bacillus cereus, Bacillus megaterium, and Staphylococcus aureus and Gram negative Salmonella typhi, Salmonella paratyphi, Pseudomonas aeroginosa, Shigella dysenteriae, Vibrio cholerae, and Escherichia coli. Significant minimum inhibitory concentrations compared to tetracycline were obtained against the above organisms. In antifungal assay, the extract inhibited the growth of Aspergillus flavus, Candida albicans and Fusarium equisetii by 38.09 ± 0.59, 22.58 ± 2.22, and 22.58 ± 2.22%, respectively. The extract showed a significant LC50 value compared to vincristine sulfate in cytotoxic assay. The results evidenced the potential antioxidative, antimicrobial and cytotoxic capacities of Leea inidica leaf extract to be processed for pharmaceutical use.  相似文献   

8.
Three field populations of Cx. pipiens (L.) mosquitoes were collected from three different localities in Riyadh city. They were tested for developing resistance against commonly used insecticides to control mosquitoes in Riyadh. Two populations from Wadi Namar (WN1 and WN2) were highly resistant to deltamethrin (187.1- and 161.4-folds respectively). The field population from AL-Wadi district (AL-W) showed low resistance to lambda-cyhalothrin (3.8-folds) and moderate resistance to beta-cyfluthrin and bifenthrin (14- and 38.4-folds respectively). No resistance to fenitrothion was observed in WN1 population. Fenitrothion concentrations required to inhibit 50% of Acetylcholinesterase (AChE) activity in both WN1 population and the laboratory susceptible strain (S-LAB) were 0.073 and 0.078 ppm respectively. Piperonyl butoxide suppressed resistance to pyrethroid insecticides (>90%) in field populations indicating that oxidases and/or esterases play an important role in the reduction of pyrethroids toxicity. These results should be considered in the current mosquitoes control programs in Riyadh.  相似文献   

9.
Isolations from oak symptomatic of Acute Oak Decline, alder and walnut log tissue, and buprestid beetles in 2009–2012 yielded 32 Gram-negative bacterial strains showing highest gyrB sequence similarity to Rahnella aquatilis and Ewingella americana. Multilocus sequence analysis (using partial gyrB, rpoB, infB and atpD gene sequences) delineated the strains into six MLSA groups. Two MLSA groups contained reference strains of Rahnella genomospecies 2 and 3, three groups clustered within the Rahnella clade with no known type or reference strains and the last group contained the type strain of E. americana. DNA–DNA relatedness assays using both the microplate and fluorometric methods, confirmed that each of the five Rahnella MLSA groups formed separate taxa. Rahnella genomospecies 2 and 3 were previously not formally described due to a lack of distinguishing phenotypic characteristics. In the present study, all five Rahnella MLSA groups were phenotypically differentiated from each other and from R. aquatilis. Therefore we propose to classify the strains from symptomatic oak, alder and walnut and buprestid beetles as: Rahnella victoriana sp. nov. (type strain FRB 225T = LMG 27717T = DSM 27397T), Rahnella variigena sp. nov. (previously Rahnella genomosp. 2, type strain CIP 105588T = LMG 27711T), Rahnella inusitata sp. nov. (previously Rahnella genomosp. 3, type strain DSM 30078T = LMG 2640T), Rahnella bruchi sp. nov. (type strain FRB 226T = LMG 27718T = DSM 27398T) and Rahnella woolbedingensis sp. nov. (type strain FRB 227T = LMG 27719T = DSM 27399T).  相似文献   

10.
《Journal of Asia》2023,26(1):102025
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.  相似文献   

11.
Polyphosphate (polyP), synthesized by polyP kinase (PPK) using the terminal phosphate of ATP as substrate, performs important functions in every living cell. The present work reports on the relationship between polyP metabolism and bioinsecticide production in Bacillus thuringiensis subsp. israelensis (Bti). The ppk gene of Bti was cloned into vector pHT315 and the effect of its overexpression on endotoxin production was determined. Endotoxin production by the recombinant strain was found to be consistently higher than that by the wild type strain and the strain that carried the empty plasmid. The toxicity of the recombinant mutant strain (LC50 5.8 ± 0.6 ng ml?1) against late 2nd instar Culex quinquefasciatus was about 7.7 times higher than that of Bti (LC50 44.9 ± 7 ng ml?1). To our knowledge this is the first reported study which relates polyP metabolism with bioinsecticide biosynthesis.  相似文献   

12.
《Process Biochemistry》2014,49(1):19-24
Enterodiol (END) possesses the estrogenic and antiestrogenic activities, which could prevent the development of breast cancer and prostate cancer, as well as menopausal syndrome.Previous studies in our laboratory set up a bio-transformation method for largely yielding secoisolariciresinol (SECO) from the substrate of defatted flaxseeds by strain Bacteroides uniformis ZL-I. In this research, another two single colonies, designated as strain ZL-II and strain ZL-III, were isolated, which were closely related to Eubacterium limosum species (ZL-II), and Eggerthella lenta species (ZL-III) on the basis of 16S rRNA gene sequence data. Under the combining actions of strains ZL-(I + II + III), END could be produced from defatted flaxseed directly, ZL-II was proved to possess the activities of demethylation, while ZL-III had the activities of dehydroxylation. Secoisolariciresinol diglucoside (SDG) existed in the form of oligomeric with 3-hydroxy-3-methyl glutaric acid in flaxseed could be efficiently transformed into END under the co-culture of strains ZL-(I + II + III), with the conversion rate of more than 90%. The method for mass-producing END from defatted flaxseed reported here is meaningful not only for the medicinal values of END but also for the resource utilization of flaxseed materials.  相似文献   

13.
The distribution of resistant individuals is determined by the amount of movement between populations. The differential rate of dispersal of a susceptible and a pesticide-resistant strain could influence the resistance dynamics under field conditions. The dispersal rate and dispersal efficiency of the susceptible and propargite-resistant strains of Tetranychus urticae were measured in separate-release and mixed-release experiments. The diffusion coefficient (D) of both strains did not differ significantly (P > 0.344) and an estimate of the asymptotic rate of advance (2  rD) (for one generation) was estimated at 0.1047 and 0.0930 cm per degree day for the susceptible and propargite-resistant strains, respectively. The dispersal efficiency of the two strains differed significantly (P < 0.005) as more susceptible mites than propargite-resistant mites crossed into specified zones more quickly after 290 and 366 degree days. Significantly (P < 0.05) higher number of susceptible adults, immatures and eggs were found in the outer most zone of an arena as compared to that of the propargite-resistant mites. The bioassay of the two strains showed a similar pattern of the spread of the adult females across the specified zones in the mixed-release experiment. The relatively lower dispersive tendency of the propargite-resistant T. urticae and the smaller proportion of adult females exhibiting that behaviour increase the chances of developing resistant ‘hotspots’ in field specially after an acaricide application.  相似文献   

14.
Exogenous and endogenous stages of Eimeria perforans naturally infected rabbits in Saudi Arabia were described. The prevalence of infection was 75%. Oocysts were ovoid to elliptical and measured 16 × 10 μm. The four dizoic sporocysts were ovoid and measured 7 × 5 μm. Endogenous stages were restricted to the duodenum. Meronts, microgamonts, macrogamonts and young oocysts were recorded and described.  相似文献   

15.
The resistance levels to carbamate (CB) and organophosphate (OP) insecticides were determined by topical application in 14 field strains of Nilaparvata lugens. The resistance levels of N. lugens to CB and OP were 1.3–47.5-fold and 1.4–14.4-fold higher than a susceptible strain, respectively. A quantitative sequencing (QS) protocol was established to determine the allele frequencies of four acetylcholinesterase point mutations putatively associated with CB and OP resistance. The allele frequencies of the four mutations (G119A, F/Y330S, F331H and I332L) in field strains' ranges are ca. 0.0–51.7%, 0.0–88.9%, 5.1–56.0% and 6.7–57.3%, respectively. The F331H and I332L were tightly linked to each other, suggesting that these mutations may occur simultaneously. In correlation analysis, G119A was not well correlated with actual resistance levels (r2 = < 0.232), whereas F331H and I332L showed a better correlation with the resistance levels of benzofuranyl methylcarbamates (r2 = 0.595). This finding indicates that F331H and I332L mutation frequencies may be used as molecular markers for detecting carbamate resistance in N. lugens. A QS protocol detecting the F331H and I332L mutation frequencies could therefore be employed as a supportive tool for the rapid monitoring of CB insecticide resistance levels in N. lugens.  相似文献   

16.
d-Amino acid oxidase from Rhodosporidium toruloides (RtDAO) and Fe3O4 magnetic nanoparticles were encapsulated simultaneously within biomimetic silica, as mediated by polyallylamine. The capacity for this enzyme reached 193 mg/g of biomimetic silica when 15 mg/ml RtDAO was used during encapsulation; the average encapsulation efficiency was approximately 74%. The Tm value (the temperature at which 50% of the initial activity was retained after 1 h of incubation) was increased from 44.3 °C of the free RtDAO to 57.7 °C, clearly indicating the thermal stability was improved by encapsulation. In the presence of 50 mM hydrogen peroxide, encapsulated RtDAO had a half-life of 148 min, an approximately 2-fold increase in resistance to hydrogen peroxide as compared to 78-min half-life of the free form. The encapsulation process is simple and can be completed within minutes; besides, the resultant enzymes can be recovered easily under magnetic field. Such preparation of encapsulated d-amino acid oxidase could be exploited for many potential applications.  相似文献   

17.
Adaptation to temperature changes is vital to reduce adverse effects on individuals, and some may present phenotypic changes, which might be accompanied with physiological costs in fitness traits. The objective of this study was to determine whether the two strains of the herbivore Eccritotarsus catarinensis, a biological control agent against water hyacinth in South Africa, differ in their responses to temperature according to their geographical origin.We experimentally quantified the responses of the two strains, at three constant temperatures: 20 °C, 25 °C and 30 °C, using laboratory cultures that originated from Brazil and Peru, where climates differ. Reproductive output, egg hatching rate, sex ratio and longevity were recorded at each temperature. Fitness traits for both strains were significantly reduced at 30 °C compared with 25 °C and 20 °C in two successive generations. Nonetheless, Peruvian individuals continued their development at 30 °C, whereas Brazilian individuals that succeeded in emerging did not continue their development. In contrast, sex ratio was unaffected by temperature. The Peruvian strain of E. catarinensis presented different phenotypes depending on temperature and was more adapted to extreme high temperature than the Brazilian strain. The tropical origin of the population induces the insect to tolerate the extreme high temperature. We suggest that the Peruvian strain could be better suited for release to control water hyacinth in nature, particularly in regions where temperature is high.  相似文献   

18.
《Bioresource technology》2000,71(3):267-271
Oil of Mentha piperita L. (Peppermint oil), a widely used essential oil, was evaluated for larvicidal activity against different mosquito species: Aedes aegypti, Anopheles stephensi and Culex quinquefasciatus by exposing IIIrd instar larvae of mosquitoes in enamel trays 6 × 4 inch2 size filled to a depth of 3 inch with water. Of the three species tested Cx. quinquefasciatus was most susceptible followed by Ae. aegypti and An. stephensi. Application of oil at 3 ml/m2 of water surface area resulted in 100% mortality within 24 h for Cx. quinquefasciatus, 90% for Ae. aegypti and 85% for An. stephensi. For Ae. aegypti 100% mortality was achieved at 3 ml/m2 in 48 h or 4 ml/m2 in 24 h. For An. stephensi 100% mortality was observed at 4 ml/m2 in 72 h. The emergence at 3 ml/m2 was also inhibited to a great extent and the few adults which emerged did not ovipost even after taking a blood meal. The oil showed strong repellent action against adult mosquitoes when applied on human skin. Percent protection obtained against An. annularis, An. culicifacies, and Cx. quinquefasciatus was 100%, 92.3% and 84.5%, respectively. The repellent action of Mentha oil was comparable to that of Mylol oil consisting of dibutyl and dimethyl phthalates.  相似文献   

19.
A novel moderately thermophilic, heterotrophic anaerobe, designated strain LG1T, was isolated from the Mariner deep-sea hydrothermal vent field along the Eastern Lau Spreading Center and Valu Fa Ridge. Cells of strain LG1T were motile rods, occurring singly or in pairs, 0.6 μm in width and 1.2 μm in length. The strain LG1T grew between 40 and 70 °C (optimum 50–55 °C), at a pH between 5 and 8 (optimum pH 6.5) and with 7.5–50 g L−1 NaCl (optimum 30 g L−1). Sulfur, cystine and thiosulfate were reduced to sulfide, and cell yield was improved in the presence of cystine. Strain LG1T was an organotroph able to use a variety of organic compounds. Phylogenetic analysis based on 16S rRNA gene sequence comparisons indicated that strain LG1T was affiliated to the genus Marinitoga within the order Petrotogales. It shared 95.34–96.31% 16S rRNA gene sequence similarity with strains of other Marinitoga species, and is most closely related to Marinitoga okinawensis. Genome analysis revealed the presence of a prophage sharing high sequence homology with the viruses MPV1, MCV1 and MCV2 hosted by Marinitoga strains. Based on the data from the phylogenetic analyses and the physiological properties of the novel isolate, we propose that strain LG1T is a representative of a novel species, for which the name Marinitoga lauensis sp. nov. is proposed; the type strain is LG1T (=DSM 106824 = JCM 32613).  相似文献   

20.
The present study was undertaken to examine the attenuative effect of Piper betle leaf extract (PBE) against cadmium (Cd) induced oxidative hepatic dysfunction in the liver of rats. Pre-oral supplementation of PBE (200 mg/kg BW) treated rats showed the protective efficacy against Cd induced hepatic oxidative stress. Oral administration of Cd (5 mg/kg BW) for four weeks to rats significantly (P > 0.05) elevated the level of serum hepatic markers such as serum aspartate transaminase (AST), serum alanine transaminase (ALT), alkaline phosphatase (ALP), lactate dehydrogenase (LDH), gamma-glutamyl transpeptidase (GGT), bilirubin (TBRNs), oxidative stress markers viz., thiobarbituric acid reactive substances (TBARS), lipid hydroperoxides (LOOH), protein carbonyls (PC) and conjugated dienes (CD) and significantly (P > 0.05) reduced the enzymatic antioxidants viz., superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), glutathione S-transferase (GST), glutathione reductase (GR) and glucose-6-phosphate dehydrogenase (G6PD) and non-enzymatic antioxidants Viz., reduced glutathione (GSH), total sulfhydryls (TSH), vitamin C and vitamin E in the liver. Pre-oral supplementation of PBE (200 mg/kg BW) in Cd intoxicated rats, the altered biochemical indices and pathological changes were recovered significantly (P > 0.05) which showed ameliorative effect of PBE against Cd induced hepatic oxidative stress. From the above findings, we suggested that the pre-administration of P. betle leaf extract exhibited remarkable protective effects against cadmium-induced oxidative hepatic injury in rats.  相似文献   

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