Contact Toxicity and Antifeedant Activity of Aconitum flavum Extract against Cabbage Worm

[ Objective] The paper was to study the contact toxicity and antifeedant activity of Aconitum flavum against cabbage worm. [ Method ] In- sect dipping method was adopted to determine the contact toxicity of the extracts of A. fiavum extracted from five polar solvents including ethanol, petroleum ether, ether, ethyl acetate, n-butanol and water; leaf dish method was adopted to determine the antifeedant activities of five solvent ex- tracts including ethanol, petroleum ether, ether, ethyl acetate, n-butanol and water against cabbage worm, [ Result] Extracts of A. flavum had high contact toxicity against cabbage worm. When the concentration was 100.00 mg/ml, the corrected mortality at 48 h roached 97.24%, and the insec- ticidal activities of five solvent extracts against cabbage worm in sequence were water 〉 n-butanol 〉 ethyl acetate 〉 ether 〉 petroleum ether, the cor- rected mortality of water extract at 48 h was 95.87% ; the antifeedant activities of five solvent extracts in sequence were water 〉 n-butanol 〉 ethyl ac- etate 〉 ether 〉 petroleum ether. [ Conclusion] Extracts of A. flavum had strong contact toxicity and antifeedant activity against cabbage worm, and the active ingredients with contact toxicity and antifeedant activity might be a kind of polar compound.

Toxicity Effects of Water Extract of Euphorbia fischeriana Steud.against Silkworm(Bombyx mori)

[Objective] Taking silkworm （Bombyx mori） as the test material, the research aimed to study the toxicity effects of Euphorbiafischeriana Steud. against the insects in Lepidoptera. [ Methods ] Water extract was prepared with fresh perennial E. fischer/ana Steud. , which was applied in silkworm with different methods including daubing the extract on silkworm back, soaking silkworm in the extract and feeding silkworm with the mulberry leaves daubed by the extract. [ Re- suits] Those silkworms whose backs were daubed with the water extract had no obvious poisoning symptom. The silkworms soaked for 1 and 3 min could be survived for about 7 d; the silkworms soaked for 5 min could be survived for about 2 d; and the silkworms soaked for 15 rain could be survived for 10 h at most. Those silk- worms fed with mulberry leaves daubed by water extract completely died after 2 d. [ Conduslons ] The water extract of E. fischer/ana Steud. had significant contact toxicity and stomach poisoning against silkworm.

Toxicity of copper oxide nanoparticles on agriculturally important soil rhizobacteria Bacillus megaterium

Copper oxide nanoparticles are an integral part of modern agrochemical industries,such as pesticides and nano fertilizers.It has been extensively reviewed and reported that the interaction of nanoparticles with plant growth-promoting rhizobacteria(PGPRs)may be toxic due to their accumulation in the soil and may remain in contact for a long time which causes a negative impact on the soil microbial community.The study presented here,investigates the impact of the copper oxide nanoparticles on the isolated PGPR species Bacillius megaterium AGNTL MM7 in invitro conditions.We observed that the formation of Reactive Oxygen Species(ROS)at¼of Minimum Inhibitory Concentrations(MIC)of CuO nanoparticles resulted in a decrease in the Indole Acetic Acid(IAA)production(83.02μg/ml)as the marker of the nanoparticles mediated stress on the Bacillus megaterium AGNTL MM7.The minimum inhibitory concentration(MIC)assay was observed at 4 mg/ml.The solubility of CuO nanoparticles was 0.014%and the Nanotracking analyzer estimated the mean average size 188 nm in a liquid medium such as water.Transmission Electron Microscopic(TEM)studies observed that the concentration of 1 mg/ml nanoparticles showed a strong affinity with cell envelope and caused a significant negative impact on the microorganism,resulting in 58%inhibition in IAA production was observed in comparison to the control i.e.,197.8μg/ml.The flow cytometric analysis also significantly validated the toxicity at the same concentration.

Microwave-assisted Extraction and Biological Activity Determination of Insecticidal Components of Seleng Wormwood(Artemisia selengensis Turcz.)

[Objective] The aim was to study the biological activity of insecticidal components of Seleng Wormwood on cabbage butterfly （Pieris rapae）.[Method] With the assisted condition of microwave heating,ethanol,ethyl ether,water and methylbenzene were selected as solvents to extract Seleng Wormwood,and the antifeedant,stomach toxicity,contact toxicity and fumigation activities of various solvent extracts against cabbage butterfly were determined.[Result] Various solvent extracts all showed certain antifeedant,stomach toxicity,contact toxicity and fumigation activity against the larvae of cabbage butterfly,and the biological activity of ethanol extract was the strongest.[Conclusion]The results could provide reference for development and utilization of botanical pesticides of Seleng Wormwood.

Bioactivities of Extracts from Toona sinensis against Sitophilus zeamais

[ Objective ] The repellent activities and contact toxicity of extracts from Toona sinensis against Sitophilus zeamais were studied. [ Meth- od] 95% alcohol, petroleum ether and dichloromethane were selected to extract the active components from the leaves and barks of T. sinensis, respectively. And then the extracts were prepared at 0.6, 0.3, 0.15 g/ml to study the biological activity against S. zeamais in lab. [ Result J The petroleum ether extracts from the leaves of T. sinensis had significantly repellent effects on S. zeamais, but the extracts from T. sinensis with three solvents had no obvious contact toxicity against S. zeamais. [ Conclusion ] The petroleum ether extracts from S. zeamais had certain repellent activity.

Contact Activity of Root Extracts from Macleaya cordata against Tenhrio motlitorlin(L.)

[Objective] The study was to screen the active part from roots of Macleaya cordata. [Method] Dipping method was used to study the contact activity of ethanol extract and 4 kinds of extracts by petroleum, ethyl acetate, n-butanol and water from the root of M. cordata on 2nd and 6th instars larvae of T. motlitorlin（L.）. [Result] The corrected mortality rate of T. motlitorlin increased with the increase of extract concentration. When the concentration was 100 mg/ml, the contact activity of ethyl acetate extract against 2nd instar larvae of T. motlitorlin was the highest, the corrected mortality rate at 48 h reached 80.95%, and LC50 was 65.532 9 mg/ml. The overall performance of insecticidal activity was as follows： ethyl acetate layer petroleum layer = n-butanol layer total extracts （ethanol） water layer. The contact toxicity of ethanol extract and petroleum extract against 6th instar larvae of T. motlitorlin was the highest, and the corrected mortality rate at 48 h reached 71.42% and 66.67%, LC50 were 83.899 8 and 86.687 7 mg/ml, respectively. The overall performance of insecticidal activity was as follows： total extracts （ethanol） petroleum layer ethyl acetate layer n-butanol layer water layer. [Conclusion] The insecticidal active components of M. cordata root were distributed within the polarity range of petroleum and ethyl acetate, and the part could be further separated and identified.

Synthesis and Insecticidal Activity of Novel Camptothecin Derivatives Containing Analogs of Chrysanthemic Acid Moieties

Creating high-efifcient and environment-friendly pesticides is very important to produce the pollution free agriculture food and maintain the balance of the survival environmental of the human being. According to reports, camptothecin （CPT） and its derivatives are now being explored as a class of botanical insecticide in agriculture due to its novel mode of action. In order to improve the insecticidal activity of CPT, ten novel camptothecin （1） and 10-hydroxycamptothecin （2） derivatives （1a, 1b, 1c, 1d, 1e;2a, 2b, 2c, 2d, 2e） were designed and synthesized via esteriifcation with analogs of chrysanthemic acid, which have outstanding insecticidal activity. The results showed that compound 2a exhibited potent antifeeding effect and the best contact toxicity among the target compounds against the third-instar larvae of beet armyworm, Spodoptera exigua H＆#252;bner. Compound 2a was also found to be the most effective cytotoxic compound to the tested insect cell lines, IOZCAS-Spex-II, which were established from the fat bodies of S. exigua. It was proposed that the 10-hydroxyl group in the camptothecin derivatives is a key factor for the antifeeding activity of a compound. The nature of the substituents was considered the major factor in determining the insecticidal activity of these compounds.

Contact toxicities of imidacloprid on rice brown plant hopper(Nilaparvata lugens Stal)

Rice brown planthopper (BPH) (Nilaparvata lugens Stal, ) which occurs 4 generations within one year in Jiangsu Province has become a serious pest and causes loss of yield on rice every year in this region. The contact toxicities of imidacloprid and methamidophos to rice BPH were tested by means of immerse topical application method and a field trial from 1993 to 1994. A randomized complete design was laid out in 6 treatments with three replications.

Alstonia boonei De Wild oil extract in the management of mosquito(Anopheles gambiae),a vector of malaria disease

Objective:To evaluate the insecticidal potential of Alstonia boonei(A.boonei)oils and derivatives against different life stages of a malaria vector,Anopheles gambiae.Methods:The leaf,stem bark and root bark of A.boonei were collected from an open field and air dried before being blended to fine powder.Oils from this plant were extracted by cold extraction and were prepared at different concentrations.Contact toxicity of A.boonei was tested against the larvae and pupae of the insect while smoke toxicity of the plant materials in form of mosquito coil was tested against the adult insect.Results:Alstodine recorded the highest insect mortality rate and the order of susceptibility of the life stages of the insect to the plant was pupae<adult<larvae.Alstodine recorded the highest repellant activity(100%)after 4-5 h of application.However,all the treatments achieved high repellency(above 70%)after 6-7 h of application compared with the control.The formulated mosquito coil(smoke)of A.boonei oil extracts and derivatives showed high rate of protectability as they achieved above 55%protection.Moreover,alstodine(83.22%)showed the greatest smoke toxicity effect on the insect as it recorded almost the same percentage protection as the positive control(Raid synthetic insecticide)which recorded 83.56%protection.Conclusions:This present study has proven A.boonei oil extracts and derivatives as a potential botanical insecticide which could serve as a new thoroughfare of mosquito control.Moreover,the order of effectiveness of the plant can be arranged thus:alstodine>alstonine>stem bark extract>leaf extract>root bark extract.