Green synthesis,characterization,acaricidal,larvacidal,and repellent activities of copper nanoparticles of Astragalus sinicus against Hyalomma anatolicum

Objective:To green synthesize and characterize copper nanoparticles(Cu NPs)using Astragalus sinicus,as well as evaluate the acaricidal,larvacidal,and repellent activities of Cu NPs against Hyalomma anatolicum(H.anatolicum),one of the most prevalent ticks infesting cattle in Saudi Arabia.Methods:Cu NPs were green synthesized by adding the Astragalus sinicus extract to a copper sulfate solution.The acaricidal,larvicidal,and repellent activities of Cu NPs against H.anatolicum were assessed via the adult immersion test,the larval packet test,and the vertical movement behavior of tick larvae,respectively.The effects of Cu NPs on acetylcholinesterase as well as oxidative enzyme activities were examined.Results:The green synthesized Cu NPs displayed a spherical form with a size range of 15-75 nm.After exposure of adult H.anatolicum to different concentrations of Cu NPs,the viability rate of adult H.anatolicum and the mean number,weight,and hatchability of eggs were noticeably reduced,in comparison to the control group(P<0.001).In addition,the viability rate of larvae considerably declined(P<0.001)with the LC_(50)and LC_(90)values of 11.30 and 20.34μg/m L,respectively.The maximum repellent activity of Cu NPs was observed at 50,100,and 200μg/m L with complete repellent activity after 60,120,and 180 min of exposure,respectively.Cu NPs,mainly at 1/2 LC_(50)and LC_(50)concentrations,markedly suppressed the acetylcholinesterase activity of the larval stage of H.anatolicum(P<0.001).Moreover,Cu NPs,mainly at LC_(50)dose,significantly elevated malondialdehyde level while declining glutathione-S-transferase level in H.anatolicum larvae(P<0.001).Conclusions:Cu NPs show potent acaricidal,larvicidal,and repellent activities against adults and larvae of H.anatolicum.However,further studies must be performed to clarify the precise mechanisms and the efficacy of Cu NPs in practical use.

Acaricidal activity of Cymbopogon citratus and Azadirachta indica against house dust mites

Objective:To examine the acaricidal effects of the essential oil of Cymbopogon citratits leaf extract(lemongrass)and ethanolic Azadirachta indica leaf extract(neem)against house dust mites Dermatophagoides farinae(D.farinae)and Dermalophagoides pteronyssinus(D.pteronyssinus).Methods:Twenty-five adults mites were placed onto treated filter paper that is soaked with plant extract and been tested at different concentrations(50.00%,25.00%,12.50%,6.25%and 3.13%)and exposure times(24hrs,48hrs,72hrs and 96 hrs).All treatments were replicated 7 times,and the experiment repeated once.The topical and contact activities of the two herbs were investigated.Results:Mortalities from lemongrass extract were higher than neem for both topical and contact activities.At 50%concentration,both 24 hrs topical and contact exposures to lemongrass resulted in more than 91%mortalities for both species of inites.At the same concentration and exposure time,neem resulted in topical mortalities of 40.3%and 15.7%against D.pteronyssinus and D.farinae respectively;contact mortalities were 8.0%and 8.9%against the 2 mites,respectively.There was no difference in topical mortalities of D.pteronyssinus from exposure to concentrations oflemongrass and neem up to 12.50%;lemongrass was more effective than neem at the higher concentrations.Conclusions:Generally,topical mortalities of D.farinae due to lemongrass are higher than that due to neem.Contact mortalities of lemongrass are always higher that neem against both species of mites.

Acaricidal activity of Derris floribunda essential oil and its main constituent

Objective: To evaluate the acaricidal activity of the essential oil obtained from roots of Derris floribunda(D. floribunda)(Miq.) Benth, and its main constituent nerolidol against the Mexican mite Tetranychus mexicanus(T. mexicanus)(Mc Gregor).Methods: The essential oil from the roots of D. floribunda collected in the Amazon region(Brazil) was obtained by hydrodistillation. Its chemical composition was determined by GC–MS analysis. The acaricidal activities of this essential oil and nerolidol,were evaluated by recording the number of dead females(mortality) and eggs(fertility).Results: The essential oil showed sesquiterpenes as major volatile components. Nerolidol, the main component, represented 68.5% of the total composition of the essential oil. D. floribunda essential oil and nerolidol showed acaricidal activity, with LC_(50) of9.61 mg/m L air and 9.2 mg/m L air, respectively, over a 72 h period. In addition, both the essential oil and nerolidol significantly reduced the fecundity of T. mexicanus.Conclusions: Due to the economic importance of T. mexicanus and the lack of new pesticides, our data are very promising in the search for efficient and safer acaricidal products. Furthermore, this is the first report about the chemical composition and bioactivity of the essential oil of the Amazon plant species D. floribunda.

Acaricidal Activity of Boenninghausenia sessilicarpa Against Panonychus citri

Acaricidal activity of Boenninghausenia sessilicarpa against Panonychus cirri was tested in the laboratory. Four solvents were used to prepare crude extracts, petroleum ether, chloroform, ethyl acetate, and ethanol, among which ethanol was the most effective one. The results suggested that ethanol extracts of B. sessilicarpa had eminent acaricidal and ovicidal activities. Concentrated extracts were prepared using petroleum ether, chloroform, ethyl acetate, or distilled water as solvent. Mite mortality rates in the concentrated extracts by petroleum ether, chloroform, or distilled water were significantly lower than those by ethyl acetate. The LC50 values of eggs and female mites were 0.7639 and 1.1033 mg mL^-1, respectively. After liquid chromatography and thin layer chromatography, the concentrated extracts were separated into 14 groups of fractions and further tests for their acaricidal and ovicidal activities were conducted. Fraction 2 was found to possess higher acaricidal and ovicidal activities. The mortality of eggs and adult mites were 85.83 and 63.07%, respectively. Moreover, fraction 2 showed moderate oviposition inhibition effect （0.8795） against P. citri when the used dose was higher than 2.5 mg mL^-1

Synthesis,Structure and Acaricidal Activity of Tricyclohexyltin Benzoate

Tricyclohexyltin 4-amino-3-methyl-benzoate （1） and tricyclohexyltin 3,4-dime- thoxybenzoate （2） were synthesized and their crystal structures were determined by X-ray diffraction. Compound 1 belongs to the monoclinic system, space group P21/c with a = 14.0554（15）, b = 11.6947（13）, c = 16.2720（17）A, Z = 4, V= 2565.7（5） A3, Dc = 1.341 g.cm-3,μ（MoKa） = 1.016 mm-1, F（000） = 1080, R = 0.0833 and wR = 0.2964. Compound 2 is of monoclinic system, space group C2/c with a = 17.8712（6）, b = 8.4433（3）, c = 35.5783（13） A, Z = 8, V= 5366.8（3） A3, Dc = 1.360 g.cm-3,/1（MoKa） = 0.980 mm-1, F（000） = 2288, R = 0.0549, wR = 0.1279. In compounds 1 and 2, the central Sn atom is coordinated in a tetradentate manner to assume a distorted tetrahedral configuration. Preliminary biological tests showed that these two compounds have strong acaricidal activity.

The thiazoylmethoxy modification on pyrazole oximes: Synthesis and insecticidal biological evaluation beyond acaricidal activity

A series of new pyrazole oximes bearing substituted thiazole ring were designed and prepared. The structures of the title compounds were identified by spectral analyses, The results of primary bioassay indicated that some targeted compounds exhibited promising insecticidal activity besides acaricidal activity, particularly; compounds 8c and 8d were more potent against Tetranychus cinnabarinus and Plutella xylostella than other analogues.

Synthesis and acaricidal activity of strobilurin-pyrimidine derivatives

Pyriminostrobin, a new acaricide, was discovered in our previous studies. Because introducing fluorine into organic compounds can increase bioactivity, pyriminostrobin was modified as a series of strobilurin-pyrimidine derivatives for biological screening. The compounds were characterized by 1H NMR, MS and elemental analysis. Preliminary bioassays demonstrated that compounds 7e and 7i exhibited significant control against Tetranychus cinnabarinus （Boisd.） at 0.625 mg L^-1, and their acaricidal potencies were higher than pyriminostrobin in a greenhouse. The relationship between structure and acaricidal activity was also studied.

Synthesis of New 13-O-Acylavermectin Bl Aglycones

Six new 13-O-acylavermectin Bl aglycones(3-8) were synthesized from avermectin B1 aglycone and their bioactivities were evaluated against Spodoptera exigua, Spodoptera eridania, Tetranychus urticae and Aphis fabae.

Bioactivity and Kinetic Study of <i>Jatropha curcas</i>Essential Oil Extraction Using Supercritical CO₂

This study reports the extraction of Jatropha curcas leaves using supercritical CO2. Experiments were performed varying the pressure (13 and 20 MPa) and the temperature (50°C and 60°C). The model of Sovová for supercritical fluid extraction was fitted to the experimental kinetic extraction curves. Two cell sizes were used and scale up equations compared. GC analysis showed phytol, carvacrol, and hexahydrofarnesyl acetone as major compounds in all the experiments. A maximum yield of 0.95% dry-weight basis was obtained. It was observed a maximum yield (0.95% dry-weight basis) extract obtained at 20 MPa and 50°C. The results indicated that the mass yield increased with the increase of pressure. The bioassays showed that the extract of J. curcas possessed toxicity against Hyalomma lusitanicum.

Synthesis analogues of milbemycin and their bioactivity evaluation

Eight new 13-O-aminocarbonylivermectin aglycones and 4＇-O-aminocarbonylivermectin monosaccharide were synthesized from ivermectin agiycone and ivermectin monosaccharide by the selective protection of C5-OH group.Their bioactivities were evaluated against spider mites（Tetranychus cinnabarimts）,aphid（Aphis fabae） and oriental armyworm（Mytliimma sepatara）. Their structures were confirmed by ^1H NMR.MS.

Synthesis of Trihydrocarbyltin Chloride Containing Silicon and Crystal Structure of (p-Cl-C_6H_4Me_2SiCH_2)_3SnCl

A series of trihydrocarbyltin chlorides containing silicon was synthesized. The acaricidal activity was determined and the structure activity relationship was tried to be found out with the hydrophobic parameter.

Action modes of Aloe vera L. extracts against <i>Tetranychus cinnabarinus</i>Boisduval (Acarina: Tetranychidae)

Objective: This paper mainly determined the action modes of extract of Aloe vera L. against Tetranychus cinnabarinus Boisduval. Methods: The different action modes, contact action, repellent, fumigant, and oviposition inhibition property of the acetone extract of Aloe vera L. leaf against the carmine spider mite Tetranychus cinnabaribus (Boisduval) (Acarina: Tetranychidae) were investigated at 26°C ± 1°C, 75% - 80% relative humidity, and 14:10 light: day cycle in the laboratory. Results: Based on the established toxicity regression line of the Aloe vera L. acetone extract against female adult mites, the median lethal concentrations (LC50) were 0.836 and 0.167 mg/mL for 48 and 72 h, respectively. With processing time increased, the contact acaricidal activity increased and the repellent activity gradually decreased. The main modes of action of the extract against female adult mites were contact and repellent, and preferable effects were observed on adult mites. These results indicate that A. vera L. extract contains acaricidal and repellent bioactive components that may be useful in future control of the phytophagous mites.

Resistance Selection of Tetranychus cinnabarinus to Three Acaricides and Its Management Strategy

The effects of retarding resistance evolution of mixing and sequencing acaricides were studied based on the resistance selection of three acaricides to Tetranychus cinnabarinus in the laboratory. Tetrany-chus cinnabarinus was continuously selected with fenpropathrin, abamectin and pyridaban for 28, 30 and 31 generations, respectively, and resistance factor increased to 65.6, 7.2 and 1.2 time, accordingly. Results of cross-resistance determination suggested that there were no cross-resistance existed among the three acaricides. Analysis of resistance selection and estimation of realized heritability (h2) of resistance to three single and two mixed acaricides showed that a mixture of fenpropathrin+abamectin would slow resistance development compared with a sequence of fenpropathrin followed by abamectin while the mixture of pyridaben+abamectin and the sequence of pyridaben followed by abamectin would effectively retard resistance evolution.

Spirodiclofen Derivatives as Highly Potential Acaricides: Synthesis, Structure and Bioactivity

A series of new compounds as highly potential acaricides was synthesized based on the structure of spiro-diclofen. Their structures were identified by 1H NMR spectroscopy and element analysis. The bioassay indicated that most of the compounds exhibited excellent acaricidal activities, what’s more, the bioactivities of some new compounds were better than that of the commercial spirodiclofen at a concentration of 20 μg/mL. The relationship between structure and biological activity was also discussed.

Spectrophotometric Determination of Kelthane in Environmental Samples

Sensitive spectrophotometric method for determination of kelthane in sub parts per million level is described, which is based on Fujiwara reaction. Kelthane on alkaline hydrolysis gives chloroform, which can be reacted with pyridine to produce red colour. The colour is discharged by addition of glacial acetic acid. Then Benzidine (4,4’-Bianiline) reagent is added due to which a yellowish-red colour is formed which has an absorption maximum at 490nm. Beer’s law is obeyed in the range of 3.3 - 26.0 μg (0.13 - 1.04 ppm) of Kelthane per 25ml of final solution. The molar absorptivity and Sandell’s sensitivity were found to be 4.32 × 105 L?mol–1?cm–1 and 0.022 μg?cm–2 respectively. The method is found to be free from interferences of other organochlorine pesticides and various co-pollutants and can be successfully applied for the determination of kelthane in environmental samples.

Synthesis and bioactivity of novel pyrazole oxime derivatives containing oxazole ring

A series of novel pyrazole oxime derivatives containing oxazole ring were designed and synthesized. The title compounds were structurally confirmed by 1H NMR, 13C NMR spectra and elemental analyses. Preliminary bioassay results showed that some of the title compounds displayed promising fungicidal activity besides insecticidal and acaricidal activity. Particularly, compound 8c exhibited potent fungicidal activity against cucumber Pseudoperonospora cubensis beyond good insecticidal activity against Aphis craccivora and Nilaparvata lugens.

Synthesis and insecticidal bioactivities of 2,3-dihydroimidazo[1,2-a] pyridin-5(1H)-one derivatives

A novel synthesis of 2,3-dihydroimidazo[1,2-a]pyridin-5 (1H)-one 4 and its derivatives were described.Preliminary bioassays showed that some of the target compounds exhibited excellent insecticidal activities against brown planthopper (Nilaparvata lugens), cowpea aphids (Aphis craccivora) (4,5 a, 5 c, 5 g,5 h, 5 j, 5 r, 6 b, 6 e) and carmine spider mite (Tetranychus cinnabarinus (5 f, 5 s, 6 a) at 500 mg/L. Among them,compound 4 was still active against brown planthopper and cowpea aphids at 4 mg/L. The insecticidal activities were influenced by the types and position of the substituents, which provided guidance for the structure modifications.

Chitin synthesis inhibitors： old molecules and new developments

Chitin is the most abundant natural aminopolysaccharide and serves as a structural component of extracellular matrices. It is found in fungal septa, spores, and cell walls, and in arthropod cuticles and peritrophic matrices, squid pens, mollusk shells, nematode egg shells, and some protozoan cyst walls. As prokaryotes, plants and vertebrates including humans do not produce chitin, its synthesis is considered as an attractive target site for fungicides, insecticides, and acaricides. Although no chitin synthesis inhibitor has been developed into a therapeutic drug to treat fungal infections in humans, a larger number of compounds have been successfully launched worldwide to combat arthropod pests in agriculture and forestry. This review summarizes the latest advances on the mode of action of chitin synthesis inhibitors with a special focus on those molecules that act on a postcatalytic step of chitin synthesis.

Resistance status of the carmine spider mite, Tetranychus cinnabarinus and the twospotted spider mite, Tetranychus urticae to selected acaricides on strawberries

The carmine spider mite, Tetranychus cinnabarinus （Boisduval） and the twospotted spider mite, Tetranychus urticae Koch, are serious pests of strawberries and many other horticultural crops. Control of these pests has been heavily dependent upon chemical acaricides. Objectives of this study were to determine the resistance status of these two pest species to commonly used acaricides on strawberries in a year-round inten- sive horticultural production region. LC90 of abamectin for adult carmine spider mites was 4% whereas that for adult twospotted spider mites was 24% of the top label rate. LC90s of spiromesifen, etoxazole, hexythiazox and bifenazate were 0.5%, 0.5%, 1.4% and 83% of their respective highest label rates for carmine spider mite eggs, 0.7%, 2.7%, 12.1% and 347% of their respective highest label rates for the nymphs. LC90s of spiromesifen, etoxazole, hexythiazox and bifenazate were 4.6%, 11.1%, 310% and 62% of their respec- tive highest label rates for twospotted spider mite eggs, 3%, 13%, 432,214% and 15% of their respective highest label rates for the nymphs. Our results suggest that T. cinnabarinus have developed resistance to bifenazate and that the T. urticae have developed resistance to hexythiazox. These results strongly emphasize the need to develop resistance management strategies in the region.

Toxicity, inheritance and biochemistry of clofentezine resistance in Tetranychus urticae

This study evaluates the toxicological and biochemical response of two-spotted spider mites to clofentezine selection pressure. The mortality rate of Tetranychus urticae in adult females depends on increased clofentezine concentration and clofentezine was found to be effective against females. The resistance rate of the CUM strain selected 12 times once per generation with clofentezine was increased from 1.28- to 105.27-fold. The interaction of some synergists with clofentezine was analyzed in the clofentezine-resistant CLOF 12 strain. Synergists had no effect on clofentezine toxicity. The clofentezine-resistant CLOF 12 strain showed resistance against chlorpyrifos, abamectin, propargite, fenpyroximate and amitraz. The modes of inheritance of resistance to clofentezine were found to be incompletely dominant and not sex-linked. Esterase enzyme activity was detected both by gel electrophoresis and microplate reader methods, while glutathione S-transferase （GST） and monooxygenase （P450） activity were detected only by the microplate reader method. During the selection period the esterase, the GST and the P450 enzymes activities were raised from 7.69, 7.09 and 0.003 3 to 18.40, 13.11 and 0.003 7 milli-optical density/rain/rag proteins, respectively. An increase was observed in the band intensity of esterases and esterase enzymes may play a role in clofentezine resistance in T. urticae.