Guanglu Shi

Acaricidal Activities of Wikstroemia chamaedaphne Extracts against Tetranychus urticae and Tetranychus cinnabarinus (Acari: Tetranychidae)

Various extracts of Wikstroemia chamaedaphne were evaluated their acaricidal activities against Tetranychus cinnabarinus (Boisduval) and Tetranychus urticae Koch (Acari: Tetranychidae) in laboratory. According to our study, the Wikstroemia chamaedaphne extracts had significant acaricidal activities against T. cinnabarinus and T. urticae. In this study, the mean LC50 value for T. cinnabarinus and T. urticae were 0.79 mg/mL for methanol extracts of W. chamaedaphne, which were liquid partitioned from the crude methanol extracts using the water bath immersion method. Conventional column chromatography was used to further purify active components from methanol partition extracts. The obtained 7th chromatographic fraction caused a mortality rate of 94.21 % for T. cinnabarinus, 91.52 % for T. urticae, and the 10th chromatographic fraction caused a mortality rate of 85.92 % for T. cinnabarinus, 88.21 % for T. urticae.

Effects of Kochia scoparia Extracts to Activities of Several Enzymes of Tetranychus viennensis

The extract of the K. scoparia had the acardial activity against the T. viennensis. Here the female adult mites were treated by the KFCE-2 extract of K. scoparia, the effective ingredient of the extract of K. scoparia. The toxicosis symptoms of T. viennensis in response to the the KFCE-2 extract of K. scoparia were observed. After treatment, the mites went through four phases: the motionless phase (0-4h), the excited phase (4-8h), the convulsion phase (8-16h) and the death phase (16-24h). The treated mites showed the typical toxicosis symptoms, for example overexcitation, body inclination, kinetic ataxy and limb twitching. Then the protein content, the protease activity, the glutathione-S-transferase (GSTs) activity, the acetylcholine esterase (AchE) activity and the monoamine oxidase activity of the mites treated with the KFCE-2 extract of Kochia Scoparia were assayed. The results showed that the protein content and the activity of protease in T. viennensis treated with the extracts of K. Scoparia were increased and the activity of protease had the negative relationship with the protein content. The activity of GSTs was induced by the KFCE-2 extract of K. Scoparia. The activities of the AchE and the monoamine oxidase of the treated mites were inhibited. The inhibiting effects of AchE and monoamine oxidase indicated that the nervus centralis system was the main target of the extract of K. scoparia. The long time inhibition of the acetylcholinesterase activity by the KFCE-2 extract of K. scoparia blocked the nerve conduction of the treated mites and caused the treated mites to die. Keywords-Kochia Scoparia; Tetranychus viennensis; activity of enzyme

Effects of Chloroform Extracts from Kochia scoparia on Protect Enzyme activity of Tetranychus viennensis

There were few reports mentioned changes of protective enzyme activities of Tetranychus viennensis after exposed to pesticides by now. Our previous study had showed that the chloroform extracts of Kochia scoparia had effective acaricidal activity against T. viennensis. Here, the toxicosis symptoms of T. viennensis were detaiedly studied after exposed to the chloroform extracts of K. scoparia KFCE-2. We found that T. viennensis exposed to extract KFCE-2 showed typical toxicosis symptoms including over-excitation, uncoordinatedly moving, turning in circles, limb twitching and egg production decreasing in the contact action bioassay. Afterwards, we measured the potential changes of three protective enzymes [peroxidase (POD), superoxide dismutase (SOD) and catalase (CAT)] of T. viennensis in response to extract KFCE-2. Treatment with extract KFCE-2 enhanced SOD activities during the 24 hr after treatment, while the POD and CAT activity were also enhanced except two periods: the 7th - 11th hr (7th - 14th hr for CAT activity) and the 20th -24th hr after treatment. During these two periods, POD and CAT activity were inhibited. The change of the protective enzyme activities may affect the removal of the toxic oxygen free radical species, which may be one of acaricidal mechanisms of K. scoparia extract KFCE-2 against T. viennensis.

Effects of the Root Extracts of Stellera Chamaejasmel L. on the Activity of Two Enzymies of Tetranychus cinnabarinus

The root of Stellera Chamaejasmel L. was extracted with three different polarity organic solvents methanol, chloroform and petroleum ether respectively, and the acaricidal activities of the root extracts against the Tetranychus cinnabarinus were tested. The results showed that the crude petroleum ether extract of the root of S. Chamaejasmel had the strongest acaricidal activity against T. cinnabarinus. The adjusted mortality of the crude petroleum ether extract was 83.87 which was higher than the chloroform extract (48.03 ) and the methanol extract (19.84 ). The crude petroleum ether extract was re-extracted with the liquid-liquid extraction method. The acaricidal activity of the petroleum ether re-extracts was higher than that of methanol. The petroleum ether re-extracts of the root of S. Chamaejasmel was separated into 15 fractions with the column chromatography on silica gel. The acarocidal activities of the 15 fractions were identified respectively. The bioassay results indicated that the adjusted mortalities of group 2 (G2), group 7 (G7), group 8 (G8), group 9 (G9) and group 11 (G 11) were 89.99 90.23 72.17 66.30 and 61.64% respectively and were higher than the other groups obviously(the adjusted mortalities were lower than 60 F = 1.599, df = 49, P < 0.05). The G7 group with the highest acaricidal activities was selected for the further research. The activity of ATPase and acetylcholinesterase (TChE) of T. cinnabarinus were assayed by the colorimetric method after the female spider mites were treated with the G7 extracts of the root of S. Chamaejasmel. The result showed that the activities of NaK-ATPase, Ca2+Mg2+ATPase and acetylcholinesterase of the treated female mites were inhibited significantly. We supposed that the nervous system of the mites T. cinnabarinus was the main target on which the petroleum ether extract of the root of S. Chamaejasmel worked. Keywords-Stellera Chamaejasmel; Tetranychus cinnabarinus; ATPase; acetylcholinesterase

Acaricidal Activity of Methyl Palmitate to T. cinnabarinus

Methyl palmitate, a kind of fatty acid methyl ester, has been found in many plants. Many biological functions of methyl palmitate have been found. Recently we isolated the methyl palmitate from the green walnuts husks and found it has acaricidal activity that had not been reported before. Here, the acaricidal activity of methyl palmitate, industrial methyl palmitate and the mixtures of methyl palmitate and Silwet L-77 were studied respectively. The results showed that the LC 50 of methyl palmitate for female mites was 1.72 mg/ml and 7.73 mg/ml for eggs. The contact toxicity of methyl palmitate on female mites is better than on eggs. Methyl palmitate also has strong repellent effect on the female mites. Then the acaricidal activity of industrial methyl palmitate was studied, and the results showed that both of the mortality and adjusted mortality of Tetranychus cinnabarinus were more than 70% when the concentration of industrial methyl palmitate was 10 mg/ml and 8 mg/ml. In order to improve the acaricidal activity of industrial methyl palmitate, Silwet L-77, a kind of silicone surfactants, was used to mix with industrial methyl palmitate to increase the permeability of industrial methyl palmitate. The female mites were treated with nine kinds of mixture of industrial methyl palmitate and Silwet L-77. The results showed that the best mixture ratio of the industrial methyl palmitate and Silwet L-77 was 8 mg/mltimes200 ppm, 5 mg/mltimes400 ppm and 8 mg/mltimes400 ppm, and all the acaricidal activity of the three mixtures were more than 90%. The mixture ratio could be used in the production of methyl palmitate acaricides.

Acaricidal Activities of Root Extracts of Tateges erecta against Tetranychus viennensis

The acaricidal activities of root extracts from the of Tateges erecta against T. viennensis were determined under illumination and non-illumination conditions. Furthermore, the effects of chloroform extract on several enzymes activities of T. viennensis were also evaluated. According to the F-test statistical analysis, the chloroform extract had acaricidal activities against T. viennensis under non-illumination condition, but petroleum ether, and methanol extracts had no significant acaricidal activities. Furthermore, the extracts of T. erecta had photo-activated insecticidal activity, and the mean lethal concentrations (LC50) of chloroform, petroleum ether, and methanol extracts were respectively 5.8mg/mL, 3.5 mg/mL and 8.4mg/mL under illumination condition. The enzymatic activity assay suggested that the protease activities in T. viennensis were obviously inhibited by the extracts, while the activity of glutathione-s-transferase was activated under non-illumination condition, but significantly inhibited under illumination condition. The activities of esterase isozymes in T. viennensis were not significantly influenced under non-illumination condition, but were significantly inhibited under illumination condition.

The Acaricidal Mechanism of Stellera chamaejasme Extracts against Tetranychus vienneusis

Previous reports showed that the root extracts of Stellera Chamaejasme L had acaricidal activity against Tetranychus vienneusis Zacher. However, the acaricidal mechanism of the root extracts from Stellera Chamaejasme L against Tetranychus vienneusisis not clear. Here, the effects of the root extracts from Stellera Chamaejasme L. on the activities of three enzymes of mites: protease, glutathiona s-transferase (GSTs) and esterase isozyme, were detailedly studied. Our results showed that the activities of protease, GSTs and esterase isozyme in treated mites were induced by the root extracts from S. chamaejasme in the systemic toxicity bioassay compare with those of the control. The effects of the root extracts from S. chamaejasme on the activities of some important metabolism enzymes of T. vienneusis may help to elucidate the acaricidal mechanism of the root extracts from Stellera Chamaejasme L against Tetranychus vienneusis.

Antifeedant Activities of the Methanol Extracts of Stellera chamejasme against Plutella xylostella

Few studies reported the antifeedant activity of Stellera chamejasme extracts against larvae of Plutella xylostella. Here, laboratory choice and no-choice test feeding studies were conducted to assess the antifeedant activity of methanol extracts of S. chamejasme against larvae of P. xylostella. S. chamejasme Extracts caused severe feeding deterrence by 2nd or 3rd instars larvae of P. xylostella in a concentration-dependent manner, which were observed both in laboratory choice and no choice test feeding studies. Within 24 h, 93.8% feeding deterrence were achieved in 2nd or 3rd instars larvae of P. xylostella using Stellera chamejasme extracts in choice test, while 86.5 % got in no-choice test. In choice test, the AFC50 values (24 h) by 2nd or 3rd instars larvae were 41.6 mg/L for the extracts of S. chamejasme, while 569.3 mg/L got in no-choice test. S. chamejasme may be a potential source of antifeedants that can be used for P. xylostella control.

A New Report on Acaricidal Activities of Wikstroemia chamedaphne Extracts against Tetranychus viennensis (Acari: Tetranychidae)

Few studies mentioned acaricidal activity of Wikstroemia chamedaphne against Tetranychus viennensis. Here, we reported that W. chamedaphne had strongly acaricidal activity against T. viennensis. A method for purification of miticidal components from W. chamedaphne was developed as follows: Step 1, methanol immersion at room temperature; Step 2, liquid-liquid partition using petroleum ether; Step 3, conventional column chromatography and thin layer chromatography. The efficiency of various extraction techniques was also compared using extraction rate and mortality rate as its index of evaluation. Two fractions, named WCME-7 and WCME-11, were got from W. chamedaphne. WCME-7 had a LC50 value of 0.14 mg/mL for female adults T. viennensis, and 0.09 mg/mL for WCME-11. Furthermore, the effects of various extracts of W. chamedaphne on female adults, eggs and nymphae in every stage of mites were further studied. Nymphae were most sensitive to W. chamedaphne extracts, female adults were in the second place, and eggs were the least. Briefly, W. chamedaphne is a potential source of botanic acaricide against T. viennensis.

Acaricidal Mechanism of Stellera chamaejasme Extracts Against Tetranychus cinnabarinus at Subcellular Level

The extracts of S. chamaejasme were reported to have strongly acaricidal activity against T. cinnabarinus, but the mode of its action against mites is unclear. In this study, the effects on T. cinnabarinus caused at subcellular level by S. chamaejasme extracts were evaluated by transmission electron microscopy. Exposure to S. chamaejasme extracts, bilayer membrane detached and nuclear condensed. The crista of mitochondria, the stacking of Golgi cisternae, and endoplasmic reticulum became disintegrated partly. The arrangements of the muscle cells also became irregular and loose. The above-mentioned subcelluar structure change of T. cinnabarinus may be signs of dysfunction of the nervous system, digestive system, and so on. The changes of the activity of the priority target enzyme of the insecticides-Glutathione peroxidase