REPELLENT AND OVIPOSITION DETERRENT ACTIVITIES OFTHE ESSENTIAL OIL FROM MIKANIA MICRANTHA AND ITS COMPOUNDS ON PLUTELLA XYLOSTELLA

Repellent and oviposition deterrent activities of the essential oil from Mikania micrantha and five volatile compounds including limonene, a-terpinene, linalool, B-caryophylene and verbenone on the diamondback moth (DBM), Plutella xylostella, was investigated in door and in net-house. The results showed that the essential oil of the M. micrantha had significant repellant effect (at flow 100-180 mL/min) and oviposition deterrent activity at dose 1020 uL/seedling for the DBM. In five volatile compounds, a-terpinene, limonene and linalool had significant effect on repellent and oviposition deterrent of the DBM moths, but verbenone and B-caryophylene, no significantly effect was observed in repellent and oviposition deterrent.     

柠檬形克勒克酵母对温州蜜柑“国庆一号”采后贮藏的防腐效果

Citrus unshiu “Guoqing No.1” was used as material for elucidating the effect of Kloeckera apiculata suspension post-harvest treatment on preventing fruit decay during storage period. The result showed that K. apiculata preparation of 2×106CFU/mL (CFU, cloning forming unit) significantly reduced the development of decay caused by green mold, blue mold and stem rot, showing the same effect of carbendazim treatment after storage period of 100 days, and the disease incidence was controlled under 1%. The antagonist population was between 3.5×105CFU/mL and 1.7×107CFU/mL in citrus fruit, and increased 1.7×107CFU/mL after 40 days storage, and then stabilized for the remaining storage period. After storage at 5℃ for 100 days, K. apiculata strain 34-9 did not alter any quality parameters of fruit. During storage, the change of relative electrical conductivity (REC) showed a coordinate tendency with malondlaldehyde (MDA) content, which kept continuously growing from the beginning to the end of the storage. In the storage period of 25 days, the REC value and MDA content of the treatments were all significantly lower than those of water treatment, but had no obvious difference from those of carbendazim treatment. K. apiculata strain 34-9 had no effect on the enzyme activity of super oxide dismutase (SOD), but significantly improved peroxidase (POD) activity after 100 day storage.     

Potential resistance of tricin in rice against brown planthopper Nilaparvata lugens (Stål)

The aerial parts of resistant rice plant (IR36) was immersed in 85% ethanol at room temperature, and ethanol-soluble extracts were prepared. Different solvents including petroleum ether, ethyl acetate, absolute ethanol, and water were then used to separate the ethanol-soluble extracts and different solvent fractions were obtained. These fractions were tested for their effects on the mortality rate of the brown planthopper nymphae (BPH). The results indicated that EtOAc fractions had significant effects on the mortality of brown planthopper nymphae after the third day of treatment. EtOAc fractions of resistant rice plants (IR36) were separated using column chromatography over silica gel and 5,7,4′ -trihydroxy-3′,5′-dimethoxyflavone (tricin) was isolated. After the BPH were allowed to feed on diets containing tricin for 15 days, it was found that the weight of honeydew of the nymphae showed a decrease as tricin concentrations in the diets increased. The mortality rate of the nymphae increased with increasing tricin concentration. The corrected mortality rate was 58.21% for the 3rd instar nymphae and 31.75% for the 4th instar nymphae, respectively, at 500 μg/ml concentration. In addition, tricin (500 μg/ml) significantly inhibited oviposition behavior and feeding of the brown planthopper females in choice tests when spread on susceptible rice plant (TN1).     

Isolation and characterization of insecticidal activity of （Z）- asarone from Acorus calamus L.

The insecticidal activity of Acorus calamus L. rhizome-derived material against adults of Sitophilus zeamais Motschulsky was examined by using repellency method and contact toxicity. The biologically active constituent of the A. calamus rhizome was separated and identified. The results showed that the ethanol extract of A. calamus had strong repellency and contact effect to S. zeamais and the active constituent of the A. calamus was characterized as （Z）-asarone by spectroscopic analysis. Responses from the tests varied with exposure times and doses. In the repellency test, ethanol extract of A. calamus had 93.92% repellency at 629.08 μg/cm^2 but only 71.38% at 157.27 μg/cm^2 12 h after treatment. As a contrast, （Z）-asarone showed 84.50% repellency at 314.54μg/cm^2 and 77.02% at 78.63 μg/cm^2 12 h after treatment. In the filter paper diffusion test, ethanol extract of A. calamus caused 95.56% and 17.78% mortality to S. zeamais at 314.54 μg/cm^2 and 78.63 μg/ cm^2 4 days after treatment, while （Z）-asarone brought about 100.00% and 15.56% mortality at 40.89 μg/cm^2 and 15.73 μg/cm^2 respectively. These results indicate that the insecticidal activity of the A. calamus extract may be due to （Z）-asarone.     

Herbicidal Activity of Toxin from Fusarium avenaceum GD-2 against Wild Oats (Avena fatua L.)

The herbicidal activity potential of toxin from Fusarium avenaceum GD-2 was evaluated against wild oats (Avena fatua L.) in this study. The toxin was assayed in vitro to evaluate its inhibition against seed germination of A. fatua. The toxin of F. avenaceum GD-2 was shown to have an inhibitory effect of around 77.54% at 5 mg/mL against germination of A. fatua seeds. The inhibitory effect shown by the toxins against radicle had higher activity than plumule under the same concentration. The toxin of F. avenaceum GD-2 significantly diminished the plant length the part on the ground with various treatments when treated with the toxin under greenhouse conditions. However, there were no significantly different reductions in plant length and the weed fresh weight with different treatments. In detached leaf injection bioassay, the toxic metabolite was characterized after the culture filtrates crude extraction with petroleum ether, chloroform, ethyl acetate and n-butanol. The residues left after solvent evaporation were evaluated separately for their toxicity against the target weed. Residue (5 mg/mL) obtained from n butanol fraction showed the highest toxic activity when compared with others. Moreover, a host range experiments on the sensitivity of 10 plant species revealed that barnyard grasses and goosefeet were more sensitive to the toxin of the culture filtrate. Three herbicidal active compounds were isolated and purified from cultural filtrate with the same UV absorption peak. The recent results showed potential for the development of the toxins produced by F. avenaceum GD-2 as a bio herbicidal source to control and eliminate A. fatua weed.     

Nitrogen released from different plant residues of the Loess Plateau and their additions on contents of microbial biomass carbon, nitrogen in soil

An incubation method was used to investigate the nitrogen release characteristics from the residue of ten plant species which commonly grow in the northern part of the Loess Plateau. The effect of the residue on soil microbial biomass carbon (SMBC) and soil microbial biomass nitrogen (SMBN) was also determined. There were significant differences in the total N content and the C/N ratios among the different types of plant residue. The total N content of the residues ranged from 6.61 to 32.78 g kg^?1. The C/N ratio of the residue ranged from 14 to 65. There was an immediate increase in soil N after alfalfa, erect milkvetch, and korshinsk peashrub residue was added to the soil. In contrast, soil N decreased after elm, sea buckthorn, and wild peach residue was added to the soil. The soil N content remained relatively low for 14–34 days and then increased. This indicated that N immobilization occurred during the early portion of the incubation period when elm, sea buckthorn and wild peach residue was added to the soil. Soil N levels were low during the entire incubation period when simon poplar, locust, Stipa bungeana, and old world bluestem residue were added to the soil. The addition of plant residue significantly increased SMBC and SMBN in all treatments. The SMBC and SMBN values were greatest in treatments containing plant residue with high total N content and low C/N ratios. The C/N ratios of korshinsk peashrub, sea buckthorn, and wild peach residues were similar, but the amount of N released from these residues and the effects of the residue on SMBC and SMBN in soil were significantly different. This indicates that not only the C/N ratio but also the chemical composition of the plant residue affected decomposition. It is important to consider C and N release characteristics from plant residue in order to adjust the C and N balance of soil when revegetating degraded ecosystems.     

Nitrogen released from different plant residues of the Loess Plateau and their additions on contents of microbial biomass carbon, nitrogen in soil

An incubation method was used to investigate the nitrogen release characteristics from the residue of ten plant species which commonly grow in the northern part of the Loess Plateau. The effect of the residue on soil microbial biomass carbon (SMBC) and soil microbial biomass nitrogen (SMBN) was also determined. There were significant differences in the total N content and the C/N ratios among the different types of plant residue. The total N content of the residues ranged from 6.61 to 32.78 g kg^?1. The C/N ratio of the residue ranged from 14 to 65. There was an immediate increase in soil N after alfalfa, erect milkvetch, and korshinsk peashrub residue was added to the soil. In contrast, soil N decreased after elm, sea buckthorn, and wild peach residue was added to the soil. The soil N content remained relatively low for 14–34 days and then increased. This indicated that N immobilization occurred during the early portion of the incubation period when elm, sea buckthorn and wild peach residue was added to the soil. Soil N levels were low during the entire incubation period when simon poplar, locust, Stipa bungeana, and old world bluestem residue were added to the soil. The addition of plant residue significantly increased SMBC and SMBN in all treatments. The SMBC and SMBN values were greatest in treatments containing plant residue with high total N content and low C/N ratios. The C/N ratios of korshinsk peashrub, sea buckthorn, and wild peach residues were similar, but the amount of N released from these residues and the effects of the residue on SMBC and SMBN in soil were significantly different. This indicates that not only the C/N ratio but also the chemical composition of the plant residue affected decomposition. It is important to consider C and N release characteristics from plant residue in order to adjust the C and N balance of soil when revegetating degraded ecosystems.     

Interactive influence of rainfall manipulation and livestock grazing on species diversity of the herbaceous layer community in a humid savannah in Kenya

Changes in rainfall regime and grazing pressure affect vegetation composition and diversity with ecological implications for savannahs. The savannah in East Africa has experienced increased livestock grazing and rainfall variability but the impacts associated with those changes on the herbaceous layer have rarely been documented. We investigated the effect of livestock grazing, rainfall manipulation and their interaction on the composition and diversity of the herbaceous community in the savannah for two years in Lambwe, Kenya. Rainfall manipulation plots were set up for vegetation sampling;these plots received either 50% more or 50% less rainfall than control plots. Simpson’s diversity and Bergere Parker indices were used to determine diversity changes and dominance respectively. The frequency of species was used to compute their abundance and their life forms as determined from the literature. Grazing significantly increased species diversity through suppression of dominant species. Rainfall manipulation had no significant impact on plant diversity in fenced plots, but rainfall reduction significantly reduced diversity in grazed plots. In contrast, rainfall manipulation had no impact on dominance in either fenced or grazed plots. The interaction of grazing and rainfall manipulation is complex and will require additional survey campaigns to create a complete picture of the implications for savannah structure and composition.     

Human activities and nitrogen in waters

Shenzhen was a famous typical rapid-urbanization city in China, and this study compares plant species diversity in urban parks from the start of urbanization through 2011. Results show that the plant species biodiversity increased rapidly: the rate changed from 140% to 980% and the average increasing rate was 406.90%, but only 12.59% of plants spread into the park naturally. Shrubs had the highest rate; with change increasing from 20.70% to 43.54%, they replaced trees to become the dominant type. The biodiversity of native plants also increased, but their proportion relative to all species had declined. The homogenization of plant species in the parks increased; more than half of the plant species (62.24%) are located in 5–7 parks at once now, compared with 65.52% of species located in only 2–3 parks at the start of the study. The increase of species was faster than the increase of families; many new species planted belong to a few specific families. The ratio of species to families declined from 0.40 to 0.32. Results indicate that the rapid increase of plant species diversity as well as their homogenization happened in the initial stage of urbanization, and so rapid urbanization might be the major factor in the changes in plant species diversity in municipal parks. Rapid urbanization was an important cause of change in plant species diversity.     

植物乙醇提取物对三化螟控制作用研究

研究了30种植物乙醇提取物对三化螟Scirpophaga incertulas(Walker)的产卵驱避效果,并用产卵驱避率及干扰作用控制指数(IIPC)对这些效果进行评价.结果表明,处理后48 h,10种植物乙醇提取物对三化螟产卵有显著的驱避作用,其中海芋Alocasia macrorrhiza产卵驱避率最高,达到82.79%,蜜柚Citrus grandis、三叶鬼针草Bidenspilosa、马蔸铃Aristolo chiachampionii、白蝴蝶Syngonium podophyllum 4种植物的产卵驱避率为75%以上,llPC低于0.13.非选择性的试验结果同样表明海芋和屿蔸铃的乙醇提取物对三化螟具有明显的产卵驱避作用.测定结果还表明,海芋乙醇提取物处理后三化螟初孵幼虫的钻人时间是对照的2.60倍,马蔸铃是对照的1.07倍;海芋乙醇提取物处理后三化螟的钻蛀率为40%,马蔸铃乙醇提取物则为58%,两者都明显低于对照钻蛀率98.33%.此外,海芋乙醇提取物对二化螟幼虫存活率的影响不明显,但是马蔸铃乙醇提取物对幼虫存活率的影响与对照相比差异显著.     

Insect growth regulating and antifeedant effects of neem extracts and azadirachtin on two aphid species of ornamental plants

Leaf disc choice test bioassay demonstrated that formulated neem seed extracts were highly deterrent and growth regulatory to rose aphid,Microsiphum rosae (L.) and Chrysanthemum aphid,Macrosiphoniella sanbornii (Gillete). Effective concentrations to produce 50% feeding deterrence was 0.80 and 0.84% respectively for 2nd instar nymphs irrespective of bioassay duration. The disruption of aphid feeding was related to the presence of azadirachtin concentration in the extract. The toxicity on contact from the leaf surface or via topical application due to azadirachtin was significantly different and topical treatment was at least 7 times more effective for both species. Thus growth regulatory effects of azadirachtin were influenced by the host plant and the stage of treatment. Field evaluation with formulated neem extracts revealed the effect to be more of growth regulatory nature thereby showing that azadirachtin is a physiological toxin for aphid species. Neem seed extracts reduced the population of aphid on respective host plants significantly, EC₅₀ values being 0.88 and 0.96% forM. rosae andM. sanbornii respectively.     

Influence of azadirachtin on development and reproduction of Nezara viridula L. (Het., Pentatomidae)

Abstract:  The potential of azadirachtin as an insect growth regulator was evaluated in Nezara viridula L. by applying different doses to fifth instar nymphs. At doses of 200–500 ng per insect almost all the individuals died during moulting to adults and the survivors showed a great number of nymphal characteristics, and also died very soon after. At lower doses, from 2 to 50 ng per insect, approximately 50% of the adults seemed normal. No effect was observed during the last nymphal instar, even at the highest dose applied. The fertility and fecundity of adults, males and females, developing from nymphs treated with different low doses of azadirachtin were also studied. When azadirachtin was applied at 20 ng per insect on fifth instar nymphs, females developing from these nymphs showed a conspicuous reduction of fecundity. This same effect was evident when untreated females mated with males obtained from treated nymphs. Finally, azadirachtin applied at 1  μ g/cm² to the oviposition surface showed a remarkable oviposition repellency.     

双去甲氧基姜黄素对朱砂叶螨的生物活性及作用方式

在室温26℃±1℃、湿度60%～80%、光照14 h条件下,测定了天然植物活性成分双去甲氧基姜黄素对重要植食性害螨朱砂叶螨各螨态的触杀和熏蒸活性,对幼螨、若螨、成螨的驱避活性,以及对雌成螨的产卵抑制活性.采用玻片浸渍法测得双去甲氧基姜黄素对朱砂叶螨雌成螨48 h的LCso为0.433 mg·mL-1.在0.883 mg·mL-1(LC70)的浓度下,双去甲氧基姜黄素对朱砂叶螨不同螨态触杀活性的大小依次为幼螨＞若螨＞成螨＞卵,其中对幼螨24h和48 h的校正死亡率分别为60.0%和83.3%;对朱砂叶螨各螨态的熏蒸作用不明显,024h和48 h的校正死亡率均小于3%;对幼螨、若螨以及成螨均表现出较强的驱避作用,其中对幼螨的效果最好,不同处理时间的驱避率均在85%以上,其次是若螨,对成螨的驱避性相对较差,72 h的驱避率仅为47.8%.同时对雌成螨有明显的产卵抑制作用,处理后120 h产卵抑制率达到89.3%.表明双去甲氧基姜黄素对朱砂叶螨的主要作用方式为触杀、驱避和产卵抑制作用.     

Evaluation of neemAzadirachta indica seed extracts and oils as oviposition deterrents to noctuid moths

Applications of three concentrations of oil-free neem seed extracts (Azadirachta indica A. Juss; Meliaceae) to cabbage plants in cages did not deter oviposition by individuals of three species of noctuid moths,Trichoplusia ni, Peridroma saucia, andSpodoptera litura. The concentrations used corresponded to 10, 50, and 100 ppm of the main active ingredient, azadirachtin. The total number of eggs laid per female, female longevity, and median day of oviposition were not affected. Sprays of the neem oil-based insecticide Margosan-O ^R , and a 1% aqueous emulsion of a refined neem seed oil similarly had no effect on any of the parameters studied. However, a 1% crude oil emulsion significantly reduced the proportion of eggs laid byS. litura on treated plants. Our results suggest that literature reports of significant neem-based oviposition deterrence toS. litura are the result of compounds that are removed by higher levels of processing and thus not likely to be found in most commercial neem seed formulations. Sprays consisting of highly processed neem seed extracts, used at concentrations that provide larval control, are unlikely to be generally effective as oviposition deterrents to noctuid pests.     

Studies on effects of Pelargonium citrosa leaf extracts on malarial vector,Anopheles stephensi Liston

Methanol extracts of Pelargonium citrosa leaf were tested for their biological, larvicidal, pupicidal, adulticidal, antiovipositional activity, repellency and biting deterrency against Anopheles stephensi. Larval mortality was dose dependent with the highest dose of 4% plant extract evoking 98% mortality. The extracts affected pupicidal and adulticidal activity and significantly decreased fecundity and longevity of A. stephensi. The larval, pupal and adult development were completely inhibited by the treatment. At 4% the extracts evoked strong repellent action. They also interfered with oviposition, egg hatchability, and exhibited a growth inhibiting effect against larvae and good repellency against adults of A. stephensi. The leaf extract treatment significantly enhanced biting deterrency. As naturally occurring insecticides, these plant derived materials could be useful as an alternative for synthetic insecticides controlling field populations of mosquitoes.     

Repellent effects of certain plant essential oil,plant extracts and inorganic salts to granary weevil,Sitophilus granarius (L.)

Repellency of six materials, two plant essential oil (clove and flax seed oils), two plant extracts (neem and harmal seed extracts) and two inorganic salts (silica dust and tri-calcium phosphate), to Sitophilus granarius L. were evaluated. Per cent repellency (PR) was determined for each material. Repellent effects of tested materials were proportional to concentration and higher concentration has stronger effect. Neem and flax seed oils had the strongest repellence effect (100%) after 2, 4 and 6?h of treatment at concentrations of 20, 10 and 5?mL/kg grains. Repellency activity of both oils was gradually decreased with the passage of time to reach its lowest level after 12?h of treatment. Their repellency tended to class IV or stronger during the whole exposure period. Neem and harmal seed extracts had maximum repellency (98.7 and 86.5%, respectively) at highest concentration (1000?ppm), while the lowest concentration (250?ppm) had minimum repellency effects (62.9 and 71.6%, respectively). Both extracts showed potent repellent activity against the pest and repellency values ranged between class IV and class V. The repellency action of silica dust and tri-calcium phosphate followed nearly the same trend as shown in case of oil and extracts. High repellent activities of silica dust and tri-calcium phosphate (87.3 and 97.4%, respectively) were observed at concentration of 5?g/kg, whereas the lowest mean of repellency (56.4 and 41.0%) was recorded at concentration of 1.29?g/kg. Thus, both salts exhibited high repellency activity against the weevil and repellency values ranged between class III and class IV.     

矿物油乳剂作用下橘小实蝇的产卵拒避及触角电位反应

为了研究矿物油乳剂对害虫行为的干扰作用,测定和比较了4种矿物油乳剂对橘小实蝇Bactrocera dorsalis (Hendel)的产卵拒避效果及在其作用下该虫的触角电位反应（EAG）,并测试了其中拒避效果最好的Caltex Lovis夏用油的不同施用方式（浸蘸法和喷雾法）及不同施用浓度（150,250,350,450倍液）对橘小实蝇产卵拒避的影响。结果显示：分别用4种矿物油乳剂200倍液以浸蘸法处理香蕉,仅Caltex Lovis夏用油处理对橘小实蝇产卵拒避效果显著,其平均产卵孔数仅为清水对照的15.14%;其他3种矿物油乳剂则没有明显效果。这表明矿物油乳剂对昆虫行为的干扰作用与其组成成分相关。4种矿物油乳剂对橘小实蝇的产卵拒避效果与各矿物油乳剂的50倍液滴于滤纸条后0.5 h的雌成虫EAG值间无显著相关性,但与滴于滤纸条后3 h（滤纸条上水分已蒸发）的EAG值间有显著的负相关性,说明矿物油乳剂的挥发性组分对橘小实蝇的产卵拒避影响不大,因此推测矿物油乳剂在植物表面形成的油膜对植物挥发性物质的封闭作用与其产卵拒避效果可能有一定的关系。浸蘸法不同浓度处理间的产卵拒避效果无显著差异,均明显高于喷雾法处理及清水对照。在喷雾法处理中,仅150倍液有显著产卵拒避效果。这说明,矿物油乳剂需要在植物表面达到一定的沉积量,才能对橘小实蝇有较好的产卵拒避作用。与喷雾法相比,浸蘸法可能较利于矿物油在植物表面的沉积,这也佐证了矿物油乳剂所形成油膜的封闭性与其产卵拒避效果有一定的关系。     

Impact of azadirachtin on vine weevil (Coleoptera: Curculionidae) reproduction

Abstract 1 The dose–response of azadirachtin on vine weevil, Otiorhynchus sulcatus (Fabricius), reproduction is investigated by confining adults to feed on treated Taxus × media leaves, and by counting and evaluating development in the resulting eggs. 2 A dosage‐dependent reduction in oviposition is discovered for foliar surface residues of azadirachtin, with an EC₅₀ of 25–50 parts per million (p.p.m) and 99.2% inhibition of viable egg production with 100 p.p.m. 3 Switching weevils from treated to untreated foliage allows reproductive capability to be restored for weevils that cease egg laying after azadirachtin exposure of 50 p.p.m. Weevils that had already started laying eggs in untreated groups soon cease oviposition once switched to azadirachtin‐treated foliage. 4 A transovarial effect results in a decrease in the percentage of viable eggs as the azadirachtin concentration increases. 5 The amount of feeding on foliage does not appreciably decrease at these hormonally effective concentrations, and adult weevil mortality is only slightly greater in the azadirachtin‐treated groups. Therefore, the overall effect of azadirachtin on weevil populations in the field is difficult to assess, except by collecting weevils to determine whether they are able to lay viable eggs.     

Behavioral and developmental effects of neem extracts on Clavigralla scutellaris (Hemiptera: Heteroptera: Coreidae) and its egg parasitoid, Gryon fulviventre (Hymenoptera: Scelionidae)

Extracts of neem, Azadirachta indica A. Juss, negatively affected feeding and development of Clavigralla scutellaris (Westwood), a coreid pest of pigeonpea, Cajanus cajan (L.) Millspaugh. Labial dabbing, pod wall penetration, and seed damage by fifth instars were significantly reduced on beans, Phaseolus vulgaris (L.), that had been dipped in aqueous, methanolic, or hexane extracts of neem seed kernel. When fourth instars were dipped directly into aqueous extract, developmental abnormalities of the wings occurred at all levels tested and fecundity dropped to zero at concentrations above 0.3125%. The LC50 value was 3.14% (220 ppm azadirachtin) at 8 d. The scelionid wasp Gryon fulviventre (Crawford) is an important natural enemy of Clavigralla spp.; egg mortality from this parasitoid ranged from 37 to 85% during the fall cropping season. Feeding by newly emerged wasps was dramatically reduced when honey was mixed with aqueous neem suspension, but 6-d survivorship of adults did not differ significantly from that of the control. Wasp oviposition behavior was altered slightly when coreid eggs were treated with neem: the period of antennation was significantly extended, but time for drilling, oviposition, and marking was unaffected. Neem-dipped eggs were accepted for oviposition and progeny emerged successfully from these treated eggs. Exposure of already parasitized eggs to neem did not interfere with progeny emergence, longevity, or sex ratio. Thus, neem extract and egg parasitoids seem to be compatible and promising control strategies for C. scutellaris. Our results suggest that use of neem against pod-sucking bugs will not interfere with natural control provided by G. fulviventre.