西班牙河碳酸盐岩对茶园土壤状况和土壤细菌群落的影响

【目的】探讨西班牙河碳酸盐岩(Spanish river carbonatite, SRC)对茶园土壤酸化、重金属以及土壤细菌多样性和群落结构的影响,为茶园土壤改良提供科学依据。【方法】通过盆栽和大田试验,应用pH计、原子荧光法以及高通量测序技术分析施用SRC对茶园土壤pH、重金属含量以及细菌群落的影响。【结果】大田和盆栽试验均表明添加SRC可提高茶树种植土壤的pH值,盆栽试验表明低浓度的SRC的施入量就可显著降低土壤中Cd、Cu的含量,大田试验表明SRC的施用可显著降低8种重金属的含量;盆栽试验表明SRC对土壤微生物的组成有显著影响,大田试验表明施用SRC可提高土壤养分。【结论】施用SRC可显著改良茶园土壤,改良土壤重金属污染,增加茶园土壤的养分。

Identification of chorion genes and RNA interference-mediated functional characterization of chorion-1 in Plutella xylostella

Choriogenesis is the last step of insect oogenesis,a process by which the chorion polypeptides are produced by the follicular cells and deposited on the surface of oocytes in order to provide a highly specialized protective barrier to the embryo.The essential features of chorion genes have yet to be clearly understood in the diamondback moth,Plutella xylostella,a worldwide Lepidoptera pest attacking cruciferous crops and wild plants.In this study,complete sequences for 15 putative chorion genes were identified,and grouped into A and B classes.Phylogenetic analysis revealed that both classes were highly conserved and within each,branches are also species-specific.Chorion genes from each class were located in pairs on scaffolds of the P.xylostella genome,some of which shared the common promoter regulatory region.All chorion genes were highly specifically expressed in the P.xylostella adult females,mostly in the ovary with full yolk,which is a crucial period to build the shells of the eggs.RNAi-based knockdown of chorion-1,which is located on the Px_scaffold 6 alone,although had no effect on yolk deposition,resulted in smaller eggs and sharply reduced hatchability.Additionally,inhibition of PxCho-1 expression caused a less dense arrangement of the columnar layers,reduced exochorion roughness and shorter microvilli.Our study provides the foundation for exploring molecular mechanisms of female reproduction in P.xylostella,and for making use of chorion genes as the potential genetic-based molecular target to better control this economically important pest.

Above and Below Ground Interactions in Monoculture and Intercropping of Onion and Lettuce in Greenhouse Conditions

Intercropping has been seen as an advantageous strategy in sustainable agriculture. Plants however interact with one another both above and below ground with members of the same species (intraspecific) or members of a different species (interspecific) for nutrients, water and light. It is therefore essential to understand these interactions when intercropped. The objective was to examine the above and below ground interactions between onion and lettuce in monocrop and intercrop systems. We examined the various possible interactions (no competition, above ground, below ground, or full) using a full factorial randomized design under greenhouse conditions. Onion yield was highest in intraspecific above ground competition and lowest in below ground and full interspecific competition with lettuce. Dry weight of onions in above ground competition with lettuce was significantly greater than that of the control group. Fresh weight of lettuce leaves were highest in below ground and full interspecific competition treatments. The hectare model and yield results suggest that there is strong below ground competitive effect between onion and lettuce in intercrop. Asymetric interspecific facilitation was found: facilitation by onion led to increased lettuce yield but a negative effect of lettuce on onion yield was observed. Knowledge of competitive interactions between component crops can have several applications in sustainable agricultural as it helps to match the most efficient species under specific conditions.

间作牧草对茶园螨类群落多样性的影响

螨类是茶园生态系统中重要且复杂的类群之一。为了了解不同植物间作后对茶园螨类群落的组成结构和多样性的影响,2006年3月至2008年4月,在武夷山市星村镇大坪洲茶园通过间作百喜草(Paspalum notatum)或圆叶决明(Cassia rotundifolia)、留养杂草和除杂草4种不同处理,对茶园茶冠层(采用盆拍法及剪枝条法)和凋落层(采用捡取凋落物法)的螨类进行系统采样、标本鉴定和统计分析。结果表明:与留养杂草对照相比,间作百喜草或圆叶决明均显著增加了茶冠层和凋落层捕食螨的物种丰富度(S)、有效多样性指数(eH′)、个体数(N)和绝对丰度(n)。与留养杂草和除杂草这两种对照相比,间作百喜草或圆叶决明均显著增加了茶冠层和凋落层优势种圆果大赤螨(Anystis baccarum)的个体数(N)。茶冠层植食螨和腐食螨及凋落层腐食螨的所有群落指标在不同处理茶园间均无显著差异。茶冠层和凋落层螨类群落物种丰富度(S)和个体数(N)季节性变化明显,物种组成相似性高。间作茶园和留养杂草茶园茶冠层的螨类总个体数与其对应的凋落层螨类总个体数呈显著正相关。多样化茶园有利于保护和利用捕食螨,从而对茶园有害生物进行生态控制,促进有机茶叶可持续生产。

Electroantennogram and behavioral responses of Cotesia plutellae to plant volatiles

Plant volatiles have been demonstrated to play an important role in regulat- ing the behavior of Cotesia plutellae, a major larval parasitoid of the diamondback moth （DBM）, Plutella xylostella, but little is currently known about the function of each volatile and their mixtures. We selected 13 volatiles of the DBM host plant, a cruciferous veg- etable, to study the electroantennogram （EAG） and behavioral responses of C. plutellae. EAG responses to each of the compounds generally increased with concentration. Strong EAG responses were to 100 μL/mL of trans-2-hexenal, benzaldehyde, nonanal and cis-3- hexenol, and 10/zL/mL of trans-2-hexenal and benzaldehyde with the strongest response provoked by trans-2-hexenal at 100μL/mL. In the Y-tube olfactometer, C. plutellae, was significantly attracted by 1μL/mL of trans-2-hexenal and benzaldehyde.β-caryophyllene, cis-3-hexenol or trans-2-hexenal significantly attracted C. plutellae at 10μL/mL, while nonanal, benzyl alcohol, cis-3-hexenol or benzyl cyanide at 100μL/mL significantly at- tracted C. plutellae. Trans-2-hexenal significantly repelled C. plutellae at 100 μL/mL. EAG of C. plutellae showed strong responses to all mixtures made of five various com- pounds with mixtures 3 （trans-2-hexenal, benzaldehyde, nonanal, cis-3-hexenol, benzyl cyanide, farnesene, eucalyptol） and 4 （trans-2-hexenal, benzaldehyde, benzyl alcohol, （R）- （＋）-limonene,β-ionone, farnesene, eucalyptol） significantly attracting C. plutellae. These findings demonstrate that the behavior of C. plutellae can be affected either by individual compounds or mixtures of plant volatiles, suggesting a potential of using plant volatiles to improve the efficiency of this parasitoid for biocontrol ofP. xylostella.

Higher taxa as surrogates of species richness of spiders in insect-resistant transgenic rice

Biodiversity assessments can often be time- and resource-consuming. Several alternative approaches have been proposed to reduce sampling efforts, including indicator taxa and surrogates. In this study, we examine the reliability of higher taxon surrogates to predict species richness in two experimental rice fields of Fujian Province, southeastern China during 2005 and 2009. Spider samples in transgenic and nontransgenie plots were collected using a suction sampler. Both the genus and family surrogates had significant and positive linear relationships with species richness in the transgenic and nontransgenic rice fields. The rice varieties did not significantly influence the linear relationships. Our findings suggest that higher-taxon surrogacy could be a useful alternative to complete species inventory for risk assessments of transgenic rice.

Genomic Variations in the Tea Leafhopper Reveal the Basis of Its Adaptive Evolution

Tea green leafhopper(TGL),Empoasca onukii,is of biological and economic interest.Despite numerous studies,the mechanisms underlying its adaptation and evolution remain enigmatic.Here,we use previously untapped genome and population genetics approaches to examine how the pest adapted to different environmental variables and thus has expanded geographically.We complete a chromosome-level assembly and annotation of the E.onukii genome,showing notable expansions of gene families associated with adaptation to chemoreception and detoxification.Genomic signals indicating balancing selection highlight metabolic pathways involved in adaptation to a wide range of tea varieties grown across ecologically diverse regions.Patterns of genetic variations among 54 E.onukii samples unveil the population structure and evolutionary history across different tea-growing regions in China.Our results demonstrate that the genomic changes in key pathways,including those linked to metabolism,circadian rhythms,and immune system functions,may underlie the successful spread and adaptation of E.onukii.This work highlights the genetic and molecular basis underlying the evolutionary success of a species with broad economic impacts,and provides insights into insect adaptation to host plants,which will ultimately facilitate more sustainable pest management.