A larval specific OBP able to bind the major female sex pheromone component in Spodoptera exigua(Hübner)

Odorant binding proteins(OBPs) in insects are postulated to solubilize and transport the hydrophobic odorants across the hydrophilic antennal lymph to the olfactory receptors(ORs) located on the dendrite membrane of the sensory neurons. OBPs in adult insects have been intensively reported, but those in larvae are rarely addressed. In our study, a full-length OBP c DNA, namely Sexi OBP13, was cloned by RT-PCR and RACE strategy from the heads of Spodoptera exigua larvae. The quantitative real-time PCR(q PCR) measurement indicated that Sexi OBP13 was highly expressed in larval head, but very low in other parts of larva and was not detected in any tissues of adult. The binding affinities of Sexi OBP13 to plant volatiles and female sex pheromone components were measured by competitive binding assays. Interestingly, Sexi OBP13 displayed a high binding affinity(Ki=3.82 μmol L–1) to Z9,E12–14:Ac, the major sex pheromone component of S. exigua, while low affinities to the tested host plant volatiles(Ki27 μmol L–1). The behavioral tests further confirmed that Z9,E12–14:Ac was indeed active to elicit the behavioral activity of the third instar larvae of S. exigua. Taken together, our results suggest that Sexi OBP13 may play a role in reception of female sex pheromone in S. exigua larvae. The ecological significance of the larvae preference to the adult female sex pheromone was discussed.     

Optimization of the sex pheromone-based method for trapping field populations of Phthorimaea operculella(Zeller) in South China

Despite the identification of the potato tuber moth Phthorimaea operculella(Zeller) sex pheromone, no effective application based on this pheromone has yet been developed and evaluated. This study investigated the effect of pheromone lures, trap densities, heights of trap deployment, and pheromone doses in Yunnan, China, for the purpose of increasing the control efficiency of P. operculella and improving the application of pheromone technology in the field. The results showed that lures made of corn oil and red PVC pipes attracted the highest number of moths(11.73±1.90 per trap per day). Sex pheromone loading of 100 μg was optimal for trapping moths, but higher doses of pheromone inhibited attraction. The density of traps did not affect capture rates; therefore, the optimum trap density was 30–40 traps ha~(–1). The optimum height of trap deployment was not above the height of the plant canopy. This study provides technical details necessary for the monitoring and control of potato tuber moth using sex pheromones.     

Comparison of Headspace Solid-Phase Microextraction with Simultaneous Steam Distillation Extraction for the Analysis of the Volatile Constituents in Chinese Apricot

Volatile constituents in fully mature fruits of apricot （Prunus armeniaca L.） cultivar Xinshiji were extracted using headspace solid-phase microextraction （HS-SPME） and simultaneous steam distillation extraction （SSDE） and then analyzed using capillary gas chromatography and gas chromatography-mass spectrometry. A total of 70 components were identified by HSSPME, including 20 esters, 19 hydrocarbons, 5 alcohols, 5 ketones, 4 acids, 4 lactones, 3 aldehydes, and 10 miscellaneous components, with the esters being the dominant constituent. On the basis of the odor unit values, it is believed that the following compounds probably contributed to the fresh apricot odor： hexyl acetate, β-ionone, butyl acetate, （E）-2-hexenal, linalool, limonene, γ-decalactone, and hexanal. A total of 49 components were also detected by SSDE, including 13 hydrocarbons, 9 alcohols, 7 aldehydes, 9 esters, 4 ketones, 4 lactones, 2 acids, and 1 miscellaneous component, of which the monoterpene alcohols were the dominant constituents. It could be judged from the odor unit values that the following compounds were the major contributors to boiled apricot aroma： β-ionone, linalool, hexyl acetate, γ-dodecalactone, γ- decalactone, （E）-2-hexenal, hexanal, γ-octalactone, phenylacetaldehyde, butyl acetate, limonene, α-terpineol, and δ-decalactone. The results show that HS-SPME is a simple, rapid, and solvent-free method, which is an alternative to the classical SSDE.     

Changes of Aroma Components in Hongdeng Sweet Cherry During Fruit Development

To study the changes of aroma components in sweet cherry during fruit development, the aroma components in sweet cherry fruit from the green stage, the color stage, the commercial stage, and the ripe stage were collected using head-space solid phase microextraction （HS-SPME）, and were analyzed using a gas chromatograph-mass spectrophotometer （GC- MS）. A total of 37 compounds were identified from the sample extracts. Aldehydes, alcohols, and esters were the major constituents. The aroma components behaved differently during the fruit developmental period. C6 aldehydes and aromatic aldehydes were the main aldehydes in the sweet cherry fruit. The contents of C6 aldehydes increased quickly to 84.16% in the color stage, then decreased as ripening proceeded, and then, the contents decreased to 59.20 and 55.58% at the commercial stage and the ripe stage, respectively. The aromatic aldehydes （benzaldehyde） increased as ripening proceeded, and the maximum was found at the ripe stage. Alcohols of sweet cherry fruit included C6 alcohols and aromatic alcohols. The content of （E）-2-hexen-l-ol increased as ripening proceeded. The maximum was found at the commercial stage; alcohol was only found at the ripe stage. Ester components included ethyl acetate, butanoic acid ethyl ester, hexanoic acid ethyl ester, which increased as the fruit ripened. Hexanal, （E）-2-hexenal, benzaldehyde, （E）-2-hexen-l-ol, ethyl acetate, and hexanoic acid ethyl ester were the characteristic aroma components of sweet cherry fruit. These aroma components started to form drastically at the color stage, and the main aroma was formed at the commercial stage, which then turned bad at the ripe stage because of the presence of alcohol. So the optimal harvest time of sweet cherry was at the commercial stage.     

Compatibility Screening of Plant Extracts Synergistic with Osthole

Plant pests have been a major problem in agricultural production. To establish sustainable methods for plant pest control, 20 of plant material extracts were selected which were synergistic with Osthole to improve the performance of the osthole existing in products. The preliminary screening results indicated that Zanthoxylum bungeanum Maxim.(Z. bungeanum Maxim) compounds exerted the highest synergism. A single dose(2 000 mg · L~(-1)) of Z. bungeanum Maxim. crude extracts was used against Plutella xyllostella(P. xyllostella), Lipaphis erysimi(L. erysimi), and Sitophilus zeamais(S. zeamais). For a further examination form Z. bungeanum Maxim., in which crude extracts were mixed with osthole at different ratios. The volume ratio of 7 : 3(Z. bungeanum Maxim. extract: osthole) exhibited a more pronounced synergistic effect, and all the values of the co-toxicity coefficients were above 120. Eight distinct compounds were derived from the ethanol crude extract from Z. bungeanum Maxim.Then, the toxicity of these components to pests, such as P. xyllostella, L. erysimi, S. zeamais, Rhizopertha dominica(R. dominica),and Tribolium castaneum Herbst(T. castaneum Herbst), was determined. The results indicated that Compound 4 and Compound 7 exerted lethal effects on pest investigation. Compound 4 had the most substantial insecticidal action, at a concentration of64 ug · mL~(-1), and a death ratio of 78.3% was achieved for P. xyllostella.     

Effect of Toxins Isolated from Exserohilum monoceras （Drechsler） Leonard and Suggs on Echinochloa crus-galli （L.） Beauv.

Exserohilum monoceras （Drechsler） Leonard and Suggs is a potential biocontrol agent for the control of Echinochloa species. This fungus causes leaf blight in Echinochloa species, but does not damage rice. Phytotoxicity of the fungal fermented broth was evaluated through the bioassay and the active ingredients were preliminarily isolated by using silica gel column chromatography （CC） in this study. The most active fraction 5-Ⅲ was obtained and analyzed by gas chromatography-mass spectrometry （GC-MS）. The results show that 5-Ⅲ consisted of many compounds, in which 36 compounds accounted for 94.24% of total peak area. Di-n-butyl phthalate （DBP） displayed the highest activity accounted for 9.24% of the total peak area, suggesting that DBP may be one of the main active compounds produced by E. monoceras.     

GGE biplot analysis of yield stability and test location representativeness in proso millet(Panicum miliaceum L.) genotypes

The experiments were conducted for three consecutive years across 14 locations using 9 non-waxy proso millet genotypes and 16 locations using 7 waxy proso millet genotypes in China. The objectives of this study were to analyze yield stability and adaptability of proso millets and to evaluate the discrimination and representativeness of locations by analysis of variance(ANOVA) and genotype and genotype by environment interaction(GGE) biplot methods. Grain yields of proso millet genotypes were significantly influenced by environment(E), genotype(G) and their interaction(G×E)(P0.1%). G×E interaction effect was six times higher than G effect in non-waxy group and seven times in waxy group. N04-339 in non-waxy and Neimi 6(NM6) in waxy showed higher grain yields and stability compared with other genotypes. Also, Neimi 9(NM9, a non-waxy cultivar) and 90322-2-33(a waxy cultivar) showed higher adaptability in 7 and in 11 locations, respectively. For non-waxy, Dalat, Inner Mongolia(E2) and Wuzhai, Shanxi(E5) were the best sites among all the locations for maximizing the variance among candidate cultivars, and Yanchi, Ningxia(E10) had the best representativeness. Wuzhai, Shanxi(e9) and Yanchi, Ningxia(e14) were the best representative locations, and Baicheng, Jilin(e2) was better discriminating location than others for waxy genotypes. Based on our results, E10 and e14 have enhanced efficiency and accuracy for non-waxy genotypes and waxy genotypes selection, respectively in national regional test of proso millet varieties.     

Isolation,identification, derivatization and phytotoxic activity of secondary metabolites produced by Cladosporium oxysporum DH14, a locust-associated fungus

Three main phytotoxic compounds including lunatoic acid A(1),5Z-7-oxozeaenol(2)and zeaenol(3)were isolated from the fermentation broth of Cladosporium oxysporum DH14,a fungus residing in the locust(Oxya chinensis)gut.Two additional derivative compounds,compound 1a and 1b,were synthesized by methylation and chlorination of compound 1,respectively.The structures of such compounds were identified on the basis of spectroscopic analysis and by comparison of the corresponding data to those previously reported in the literature.Compounds 1-3 exhibited significantly phytotoxic activities against the radicle growth of Amaranthus retroflexus L.with the 50%inhibitory concentrations(IC_(50)values)of 4.51,4.80 and 8.16μg mL~(-1),respectively,which is comparable to that positive control 2,4-dichlorophenoxyacetic acid(IC_(50)=1.95μg mL~(-1)).Furthermore,the compound 1 showed selective phytotoxic activity with the inhibition rate of less than 22%against the crops of Brassica rapa L.,Sorghum durra,Brassica campestris L,Capsicum annucm and Raphanus sativus L.under the concentration of 100μg mL~(-1).Both derivatives of compound 1 had moderate phytotoxic activity against the radicle growth of A.retroflexus L.The findings of our present study suggest that these compounds provide new promising candidates for the potential management strategies of weeds.     

Effects of molybdenum on nutrition,quality, and flavour compounds of strawberry(Fragaria×ananassa Duch. cv. Akihime) fruit

Molybdenum(Mo) is an essential trace element in plant nutrition and physiology. It affects photosynthesis and photosynthate accumulation, therefore also affecting fruit quality and nutritional content. This study assessed the effects of different sodium molybdate(Na_2MoO_4) concentrations on strawberry. Five different Mo concentrations were applied in this experiment, including 0, 67.5, 135, 168.75, 202.5 g ha~(-1), respectively. The mineral concentration, including nitrogen(N), Mo, iron(Fe), copper(Cu), and selenium(Se) was assessed in strawberry fruit, as well as chlorophyll content, nutrition quality, taste and aroma. Results showed that net photosynthetic rate(P_n) and chlorophyll content for the strawberry plants increased with an increase in Mo concentration; and the contents of N, Mo, Fe, Cu, total soluble solids(TSS), titratable acidity(TA), sweetness, some sugars, organic acids, and some volatile compounds in the fruit all increased, as well. However, the Mo concentration did not significantly affect the concentrations of Se, sucrose, lactic acid, acetic acid, and some aroma compounds. Fruit sprayed with 135 g ha~(-1) Mo exhibited the highest TSS and sweetness values, as well as the highest N and Fe concentrations among all the treatments. P_n value and chlorophyll content, fructose, glucose, sorbitol and total sugar contents in fruit supplied with 135 g ha~(-1) Mo were also higher than that in other treatments. Fruit sprayed with a Mo concentration of 67.5 g ha~(-1) exhibited significantly higher ascorbic acid(AsA) values than that of control. Ninety-seven volatile compounds were identified in fruit extracted by head-space solid-phase microextraction(HS-SPME) coupled with gas chromatography-mass spectrometry(GC-MS). Fruits sprayed with 135 g ha~(-1) Mo had the highest concentrations of six characteristic aroma compounds, including methyl butanoate, γ-decalactone, ethyl butanoate, methyl hexanoate, γ-dodecalactone, and ethyl caproate.     

Sorption of Organic Compounds in Soil Organic Matter

Soil orgain matter(SOM) is the predominant component for sorption of hydrophobic organic compouds in soil and sorption by SOM ultimately affects chemical fate and availability in soil,and the degree of remediation success of contaminated soils.This paper summarizes the latest development on sorption of organic compounds in soil(natural)orgainc matter,addresses four sorption mechanisms:surface adsorption,solid-phase partitioning,dual-mode sorption,and fixed-pore sorption model,and presents future research directions as well.     

Genetic Dissimilarity of Clonal Populations of Leymus chinensis （Trin.） Tzvel in Heterogeneous and Homogeneous Habitats in Southwestern Heilongjiang Province of China

Leymus chinensis (Trin.) Tzvel is the characteristic of the Eastern Asia, and is a perennial herbaceous rhizome species on L. chinensis steppe of the Northern China, the Eastern Mongolia, and area of Outer-Baikal of Russia. It has both vegetative and sexual reproductions, and results in complexity of the population structure. Thus, it is difficult to identify distinct clones. Author used the randomly amplified polymorphic DNA (RAPD) technique to identify the clonal structure of heterogeneous and homogeneous habitats in two populations of Leymus chinensis, analyzed 260 ramets samples using 12 primers and 60 polymorphic markers (reproducible RAPD bands). The results proved clonal diversity described using PD, D, and E was higher in the HCS habitat than that in the HPS habitat. The PD, D, and E in the HCS of Songzhan population were 0.21, 0.90, and 0.91, respectively, whereas the PD, D, and E in the HPS of Songzhan population were only 0.09, 0.68, and 0.77, respectively; the PD, D, and E in the HCS of Yongle population were 0.19, 0.92 mad 0.90, respectively, correspondingly, these measures in the HPS of Yongle population were only 0.09, 0.63, and 0.79, respectively. The results also indicated that clonal population of L. chinensis in HPS habitat had lower genetic dissimilarity index than that in the HCS habitat.     

Secondary metabolites of rice sheath blight pathogen Rhizoctonia solani Kühn and their biological activities

Eight compounds were isolated from the fermentation cultures of r ice sheath blight pathogen Rhizoctonia solani Kühn. They were identified as er gosterol(1), 6β-hydroxysitostenone(2), sitostenone(3), m-h ydroxyphenylacetic acid(4), methyl m-h ydroxyphenylacetate(5), m-hydroxymethylphenyl pentanoate(6),(Z)-3-methylpent-2-en-1,5-dioic acid(7) and 3-methoxyfuran-2-carboxylic acid(8) by means of physicochemical and spectroscopic analysis. A mong them, 2, 3, 5–8 were isolated from R. solani for the first time. All the compounds were evaluated for their biological activities. 4–6 and 8 showed their inhibitory activities on the radical and germ elongation of rice seeds. 1, 4 and 7 showed moderate antibacterial activity to some bacteria. 4, 7 and 8 exhibited weak inhibitory activities on spore germination of Magnaporthe oryzae. 8 showed moderate antioxidant activity with the 1,1-diphenyl-2-picryhydrazyl(DPPH) and β-carotene-linoleic acid assays. This is the first time to reveal compounds 5, 6 and 8 from rice sheath blight pathogen R. solani to have in vitro phytotoxic activity.     

The Optimum Sowing Time for Plastic-film Corn and the Application of Two Related Theories

［1］Wu R X, Cui Z M, Pei T X, et al. Exploration of the optimum sowing time for dry-farming plastic-film corn in semi-arid area.North China Agriculture, 1999,14( Special Issue for Dry-farming Agriculture) :96. (in Chinese) ［2］Yu S L. Crop Planting(northern edition). Vol. 1. Beijing: Agriculture Press, 1984:172- 176,228. (in Chinese) ［3］Hu K N. Handbook for Agriculture Technicians. Shanghai:Shanghai Science and Technology Press, 1994:2. (in Chinese) ［4］Wang Y L. Complete Collection of Plastic-film Planting Techniques. Beijing: Agriculture Press, 1991: 388,395,389,397 -398. (in Chinese) ［5］Bai D C. Science and technology provide wings for Hetao agriculture. Modern Agriculture, 1998, (1): 1. ( in Chinese) ［6］Wang W Z. Let‘s summarize our experience and lessons to improve plastic-film corn planting in dry land. Modern Agriculture, 1997, (5) :24. (in Chinese) ［7］Wang W Z, Ding S H, Shi X W, et al. Plastic-film Corm and Interplanting. Chifeng: Inner Mongolian Science and Technology Press, 1993:28. (in Chinese) ［8］Gao G J, Li Z X. Plastic-film Planting Techniques for Hybrid Corn. Beijing: Agriculture Press, 1988: 21 - 22. ( in Chinese) ［9］Ma Z Y, Zhang B Q. Plastic-film corn planting techniques.Hebei Agricultural Science and Technology, 1990, ( 1 ): 14. ( in Chinese) ［10］Tong B Y. Plastic-film corn planting techniques. Newsletter of the Agricultural Science and Technology, 1994, (8): 6. (in Chinese) ［11］Wang E Q, Guo J B. Technique rules of plastic-film com planting in dry land. Modern Agriculture, 1995:( Supplementary Issue)16. (in Chinese) ［12］Wang Z X, Gao X X, Ye J C, et al. Ask and Answer on Key Techniques of Corn Planting. Beijing: China Agriculture Press,1998:116. (in Chinese)     

Inhibition of Na＋,K＋-ATPase in Housefly （Musca domestica L.） by Terpinen- 4-ol and Its Ester Derivatives

To reveal the insecticidal mechanism of terpinen-4-ol, the activity of Na＋,K＋-ATPase in insects tested were determined in vivo and in vitro. The results showed that terpinen-4-ol and its ester derivatives had strong contact activity to housefly and the contact toxicities of its derivatives except Z3 were all superior or equivalent to terpinen-4-ol. All the 7 compounds had strong inhibition towards activity of Na＋,K＋-ATPase. With poisoning symptom exacerbating, the inhibition rates were gradually increased. In vitro, the IC50 of terpinen-4-ol, Z1, Z2, Z4, Z5, and Z6 was 155.89, 197.98, 96.02, 121.36, 124.85, and 153.74 μg mL% respectively. There was well correlation between the LDs0 of terpinen-4-ol derivatives to housefly and the IC50 of terpinen-4-ol derivatives to Na＋,K＋-ATPase in housefly. In conclusion, Na＋,K＋-ATPase was likely the target of terpinen-4-ol against insects.     

Study on the Insecticidal and Antifeedant Activity of Extracts from Portulaca oleracea L. on Aphis sp.

[Objective] The experiment studied on insecticidal and antifeedant action of on Portulaca oleracea L.to provide theoretical basis for developing a new botanical insecticide by taking Portulaca oleracea L.as a raw material.[Method] The insecticidal activities of the ethanol extracts and 5 kinds of extracts with petroleum ether,chloroform,ethyl acetate,n-butanol,water from Portulaca oleracea L..against Aphis sp.was studied;Leaves are using drug treatments of 5 extracts anti-feedant activity of Aphis sp.[Result] The results showed that 95% ethanol extract displayed high contact activity to Aphis sp.The corrected mortality after 48 h reached 95.4 % under the concentration of 50.00 mg·ml-1 and the insecticidal activities of 5 extracts against Aphis sp.was in the order that petroleum ether > chloroform > n-butanol > ethyl acetate >water.Five kinds of anti-feeding activity in the extract of the order for the water> ethyl acetate> n-butanol > chloroform >petroleum ether.[Conclusion] The extract from Portulaca oleracea L.has a strong contact toxicity of pesticide active on Aphis sp.substances and for a small polar compounds,the strong anti-feeding activity is a kind of larger polar compounds.     

Inhibitive Mechanisms of Two Silicon Compounds on Powdery Mildew of Melon

Seedlings of Yujinxiang melon were used to investigate the effect and inhibitive mechanism of sodium silicate and nanosized silicon oxide on powdery mildew. The results showed that the severity of powdery mildew on melon seedling swas lowered significantly by treatment with either of the two silicon compounds, although the effect of sodium silicate was more powerful than silicon oxide. Application of sodium silicate to the seedlings caused significant increases in the activity of peroxidase (POD) and of β-1,3-glucosidase (GLU), both enzymes are known to be associated with the disease defence systems of plants. SEM-EDX analysis of sodium silicate-treated leaves of the melon seedlings showed an elevated level of silicon deposit at stomata and epidermis. Treatment with nanosized silicon oxide also resulted in a similar increase in silicon deposit, but the treatment did not cause a significant increase in POD activity.     

Characterization and functional analysis ofβ-1,3-galactosyltransferase involved in Cry1Ac resistance from Helicoverpa armigera (Hübner)

Carbohydrate chains are the principal antigens by which Bacillus thuringiensis(Bt) identify receptor proteins. The interaction between the antigen and Bt causes a pore in the membrane of midgut epithelial cells of insects. Receptor proteins, such as aminopeptidase N and alkaline phosphatase, are glycoproteins. Cadherin is another cell surface receptor protein which has potential glycosylation sites. Glycosyltransferase is very important for the synthesis and modification of receptor proteins. It can indirectly influence the function of Bt. The 1 950 bp full-length c DNA encoding β-1,3-galactosyltransferase was cloned from the the midgut of Helicoverpa armigera by degenerative PCR combined with RACE techniques(GAL-Harm, Gen Bank accession no.: GQ904195.1) with two potential N-glycosylation sites(157NNTI160 and 272NKTL275). Protein sequence alignments revealed that H. armigera β-1,3-galactosyltransferase shared high identity with β-1,3-galactosyltransferase in other insect species. The expression level of the β-1,3-galactosyltransferase gene in Cry1Ac-resistant H. armigera larvae was 9.2-fold higher than that in susceptible strain. The function of β-1,3-galactosyltransferase was investigated using RNAi technique. The result showed Cry1 Ac enhanced the toxicity against the si RNA-treated larvae compared with non-si RNA-treated ones, which indicated β-1,3-galactosyltransferase played an important role for the insecticidal toxicity of Cry1 Ac in H. armigera.     

Characterization and functional analysis of β-1,3-galactosyltransferase involved in Cry1Ac resistance from Helicoverpa armigera(Hübner)

Carbohydrate chains are the principal antigens by which Bacillus thuringiensis(Bt) identify receptor proteins. The interaction between the antigen and Bt causes a pore in the membrane of midgut epithelial cells of insects. Receptor proteins, such as aminopeptidase N and alkaline phosphatase, are glycoproteins. Cadherin is another cell surface receptor protein which has potential glycosylation sites. Glycosyltransferase is very important for the synthesis and modification of receptor proteins. It can indirectly influence the function of Bt. The 1 950 bp full-length c DNA encoding β-1,3-galactosyltransferase was cloned from the the midgut of Helicoverpa armigera by degenerative PCR combined with RACE techniques(GAL-Harm, Gen Bank accession no.: GQ904195.1) with two potential N-glycosylation sites(157NNTI160 and 272NKTL275). Protein sequence alignments revealed that H. armigera β-1,3-galactosyltransferase shared high identity with β-1,3-galactosyltransferase in other insect species. The expression level of the β-1,3-galactosyltransferase gene in Cry1Ac-resistant H. armigera larvae was 9.2-fold higher than that in susceptible strain. The function of β-1,3-galactosyltransferase was investigated using RNAi technique. The result showed Cry1 Ac enhanced the toxicity against the si RNA-treated larvae compared with non-si RNA-treated ones, which indicated β-1,3-galactosyltransferase played an important role for the insecticidal toxicity of Cry1 Ac in H. armigera.