Host Selection Behaviors and Progeny Suitability of Two Parasitic Wasps,Venturia canescens and Bracon hebetor,against Abnormal Host Conditions of Plodia interpunctella

Abilities of host search, oviposition and progeny development of both endoparasitoid, Venturia canescens, and ectoparasitoid, Bracon hebetor, were compared from four different abnormal host conditions of Plodia interpunctella. Wasps were allowed to parasitize normal, granulovirus-infected, frozen, tebufenozide-treated or multi-parasitized host larvae. Both wasps delayed at various times to locate most hosts that conditioned abnormally. The rates of antennal drumming and ovipositor probing of both wasps were reduced in frozen and multi-parasitized hosts. Particularly, V. canescens strongly avoided these behaviors in a host that previously parasitized by B. hebetor. Oviposition of V. canescens was completely absent in frozen and multi-parasitized hosts but suppressed in a tebufenozide-treated host. B. hebetor suppressed its oviposition only in a frozen host. In addition, the progeny development of both wasps was greatly reduced or absent in most abnormal conditions. However, B. hebetor successfully developed in a host that previously parasitized by V. canescens. Our results in overall indicate that each parasitic behaviors and progeny development are greatly dependent on different host conditions and provides a basis for studies on the mechanism underlying host-parasitoid interactions.     

Evaluating the Induced-Odour Emission of a Bt Maize and its Attractiveness to Parasitic Wasps

The current discussion on the safety of transgenic crops includes their effects on beneficial insects, such as parasitoids and predators of pest insects. One important plant trait to consider in this context is the emission of volatiles in response to herbivory. Natural enemies use the odours that result from these emissions as cues to locate their herbivorous prey and any significant change in these plant-provided signals may disrupt their search efficiency. There is a need for practical and reliable methods to evaluate transgenic crops for this and other important plant traits. Moreover, it is imperative that such evaluations are done in the context of variability for these traits among conventional genotypes of a crop. For maize and the induction of volatile emissions by caterpillar feeding this variability is known and realistic comparisons can therefore be made. Here we used a six-arm olfactometer that permits the simultaneous collection of volatiles emitted by multiple plants and testing of their attractiveness to insects. With this apparatus we measured the induced odour emissions of Bt maize (Bt11, N4640Bt) and its near-isogenic line (N4640) and the attractiveness of these odours to Cotesia marginiventris and Microplitis rufiventris, two important larval parasitoids of common lepidopteran pests. Both parasitoid species were strongly attracted to induced maize odour and neither wasp distinguished between the odours of the transgenic and the isogenic line. Also wasps that had previously experienced one of the odours during a successful oviposition divided their choices equally between the two odours. However, chemical analyses of collected odours revealed significant quantitative differences. The same 11 compounds dominated the blends of both genotypes, but the isogenic line released a larger amount of most of these. These differences may be due to altered resource allocation in the transgenic line, but it had no measurable effect on the wasps’ behaviour. All compounds identified here had been previously reported for maize and the differential quantities in which they were released fall well within the range of variability observed for other maize genotypes.     

Autoradiographic Method for Isolation of Diverse Microbial Species with Unique Catabolic Traits

A novel autoradiographic method for isolation of bacteria with unique catabolic traits was developed to overcome many of the limitations of traditional selective enrichment techniques. The method consists of five steps. (i) An environmental sample is directly plated (without enrichment) on a microporous filter atop a solid medium that allows cultivation of diverse kinds of microorganisms. (ii) Once colonies form, two replicas of the filter are prepared and the colonies are regrown. (iii) The replica filters are starved 24 to 72 h to deplete intracellular carbon reserves and then (iv) placed on Na(inf2)(sup35)SO(inf4)-containing solid media with and without a test compound. (v) Following an incubation period, the replica filters are exposed to film in order to identify colonies that incorporate more (sup35)S into cell biomass in the presence of the test compound than in its absence, providing presumptive evidence for metabolism of the compound. The colonies identified in this manner can be recovered from the master filter. To demonstrate this technique, bacteria capable of degrading benzoate were isolated from a single soil slurry by traditional enrichment as well as by autoradiography. From the enrichment culture, a single isolate able to degrade benzoate was obtained. In contrast, 18 distinct strains were obtained by purifying 19 putative benzoate-degrading colonies identified by autoradiography. Each of the 18 strains was able to completely transform the substrate, as determined by high-performance liquid chromatography analyses. The doubling times of a subset of the isolates grown in benzoate medium ranged from 1.4 to 17.1 h, whereas the doubling time of the isolate obtained by enrichment was 2.0 h. These data demonstrate that the method described here can be used to obtain a collection of diverse organisms able to metabolize a specific compound.     

South African Papilionoid Legumes Are Nodulated by Diverse Burkholderia with Unique Nodulation and Nitrogen-Fixation Loci

The root-nodule bacteria of legumes endemic to the Cape Floristic Region are largely understudied, even though recent reports suggest the occurrence of nodulating Burkholderia species unique to the region. In this study, we considered the diversity and evolution of nodulating Burkholderia associated with the endemic papilionoid tribes Hypocalypteae and Podalyrieae. We identified distinct groups from verified rhizobial isolates by phylogenetic analyses of the 16S rRNA and recA housekeeping gene regions. In order to gain insight into the evolution of the nodulation and diazotrophy of these rhizobia we analysed the genes encoding NifH and NodA. The majority of these 69 isolates appeared to be unique, potentially representing novel species. Evidence of horizontal gene transfer determining the symbiotic ability of these Cape Floristic Region isolates indicate evolutionary origins distinct from those of nodulating Burkholderia from elsewhere in the world. Overall, our findings suggest that Burkholderia species associated with fynbos legumes are highly diverse and their symbiotic abilities have unique ancestries. It is therefore possible that the evolution of these bacteria is closely linked to the diversification and establishment of legumes characteristic of the Cape Floristic Region.     

The Guts of Herbivorous Invertebrates: Promising Sources of Diverse Microorganisms with Unique Hemicellulolytic Systems

Invertebrates including insects are heterotrophic organisms and widely distributed in ecosystems. Due to their superior ability to digest various types of plant biomass taken as foods, some herbivorous invertebrates have attracted a great deal of industrial attention because such organisms include diverse cellulolytic and hemicellulolytic symbionts in their gut. Recent studies have shown that some of gut microorganisms of herbivores possess one or more extracellular fibrolytic enzymes with unique functions, which can be exploited as useful biocatalysts in various bioindustrial fields. Specifically, microbial hemicellulases with favorable biocatalytic activities are expected to be used for the development of excellent animal feed additives, production of prebiotics such as xylo‐ and mannooligosaccharides, and pretreatment of lignocellulosic biomass for the preparation of fermentable sugars. Here, we review our recent studies accomplished on several hemicellulolytic bacteria isolated from the guts of invertebrates and their glycoside hydrolases such as endo‐β‐1,4‐xylanases and endo‐β‐1,4‐mannanases.     

介壳虫寄生蜂二中国新记录属及三新种 (膜翅目: 跳小蜂科)

报道寄生介壳虫的跳小蜂 3新种 ,即采自新疆的昌吉跳小蜂 Encyrtuschangjiensis Xu,sp.n.、采自吉林的缢盾伊丽跳小蜂 Ericydnus scutellus Xu,sp.n.和采自甘肃的宽额苏泊跳小蜂 Subprionomitus frontatus Xu,sp.n.。本文也是伊丽跳小蜂属 Ericydnus Walker和苏泊跳小蜂属 Subprionomitus Mercet在我国分布的首次记录。     

敌奥姬小蜂—中国新记录属及新记录种

记述狭面姬小蜂科Elachertidae 1中国新记录属：敌奥姬小蜂属Diaulinopsis Crawford和新中国记录种：潜蝇敌奥姬小蜂Diaulinopsis arenaria Erdos,标本均保存于浙江大学应用昆虫研究所。     

洱海周边拟环纹豹蛛和星豹蛛卵袋中寄生蜂种类及其寄主选择

结合野外调查及室内实验观察,对云南洱海周边地区的拟环纹豹蛛Pardosa pseudoannulata(Boesenberg et Strand,1906)和星豹蛛Pardosa astrigera L.Koch,1878卵袋中寄生蜂种类及其寄主的选择性作了为期1年的调查研究.共发现了2种寄生蜂,即Idiolispa sp.和Idris sp.,两种寄生蜂均可不同程度地寄生在两种蜘蛛的卵袋里.Idiolispa sp.偏好寄生拟环纹豹蛛的卵袋,而Idris sp.则不具寄生偏好性,两种蜘蛛均是其适合的寄主.分析了Idiolispa sp.产生寄主选择偏好性的原因.     

Unique Structural Features of Mammalian NEIL2 DNA Glycosylase Prime Its Activity for Diverse DNA Substrates and Environments

1. Download : Download high-res image (211KB)
2. Download : Download full-size image

     

Diverse and Unique Picocyanobacteria in Chesapeake Bay, Revealed by 16S-23S rRNA Internal Transcribed Spacer Sequences

rRNA internal transcribed spacer phylogeny showed that Chesapeake Bay is populated with diverse Synechococcus strains, including members of the poorly studied marine cluster B. Marine cluster B prevailed in the upper bay, while marine cluster A was common in the lower bay. Interestingly, marine cluster B Synechococcus included phycocyanin- and phycoerythrin-rich strains.     

一个具有寄生虫病感染和恢复的捕食模型(英文)

本文假设感染的食饵有恢复率和对捕食者有收获,研究了一个对部分食饵和全部捕食者具有寄生虫病感染的捕食模型.用定性理论证明了边界和正平衡点的稳定性.结论表明恢复率和收获率对正平衡点的稳定性有影响.     

Curly Top of Cultivated Plants and Weeds and Report of a Unique Curtovirus from Iran

The incidence of curly top disease on cultivated plants and weeds was investigated in Kerman Province (southeastern Iran) from October 2003 to November 2004. A total of 1186 samples were collected in fields of sugar beet and other crops as well as within commercial plastic houses. Curtovirus infection of four field crops, three vegetables and 11 weeds was verified by indirect enzyme‐linked immunosorbent assay (ELISA) using a polyclonal antibody. An undescribed curtovirus, tentatively designated Iranian beet curly top virus (IBCTV), was isolated from three symptomatic beet samples collected randomly in widely separated regions of south‐eastern, southern and central Iran and used for molecular studies. A 672 bp segment of the coat protein (CP) gene of each isolate was amplified by PCR and sequenced. The results showed that the three isolates shared 98.5–98.7% nucleotide homology with each other but only 72.1–76.5% with other members of the genus Curtovirus. IBCTV was also detected by PCR using specific primers in other samples of sugar beet, tomato, spinach, turnip and several weed species collected in different parts of Iran. These results indicated that IBCTV is the dominant curtovirus in Iran.     

Connections with Nature and Environmental Behaviors

The influence of environmental attitudes on environmental behaviors has long been discussed. However, few studies have addressed the foundation of such attitudes. In the present study, we explored primitive belief underlying environmental attitudes, i.e., connections with nature, and its relationship with pro-environmental behaviors. Specifically, we used scales, a computerized Implicit Association Test, and a situational simulation experiment to examine both explicit and implicit connections with nature, both deliberate and spontaneous environmental behaviors, and to find correlations between environmental connectedness and environmental behaviors. Results showed that explicit connectedness was positively correlated with deliberate environmental behaviors, while implicit connectedness was positively correlated with spontaneous environmental behaviors. Additionally, explicit and implicit connectedness was independent of each other. In conclusion, the current study confirms the positive role played by connections with nature in promoting environmental behavior, and accordingly suggests means to encourage pro-environmental behavior by enhancing people’s connectedness to nature.     

Diverse Bacteria Associated with Root Nodules of Spontaneous Legumes in Tunisia and First Report for nifH-like Gene within the Genera Microbacterium and Starkeya

We characterized 34 endophytic bacterial isolates associated to root nodules collected from spontaneous legumes in the arid zone of Tunisia by 16S rDNA polymerase chain reaction (PCR)–restriction fragment length polymorphism, whole cell protein sodium dodecyl sulfate–polyacrylamide gel electrophoresis (SDS-PAGE), 16S rDNA and 16S–23S rDNA internal transcribed spacer sequencing. Phylogenetically, these isolates belong to the branches containing the genera Inquilinus, Bosea, Rhodopseudomonas, Paracraurococcus, Phyllobacterium, Ochrobactrum, Starkeya, Sphingomonas, Pseudomonas, Agromyces, Microbacterium, Ornithinicoccus, Bacillus, and Paenibacillus. These strains did not induce any nodule formation when inoculated on the wide host spectrum legume species M. atropurpureum (Siratro) and no nodA gene could be amplified by PCR. However, nifH sequences, most similar to those of Sinorhizobium meliloti, were detected within strains related to the genera Microbacterium, Agromyces, Starkeya and Phyllobacterium.     

Parasitic wasps learn and report diverse chemicals with unique conditionable behaviors

Parasitoids exploit numerous chemical cues to locate hosts and food. Whether they detect and learn chemicals foreign to their natural history has not been explored. We show that the parasitoid Microplitis croceipes can associate, with food or hosts, widely different chemicals outside their natural foraging encounters. When learned chemicals are subsequently detected, this parasitoid manifests distinct behaviors characteristic with expectations of food or host, commensurate with prior training. This flexibility of parasitoids to rapidly link diverse chemicals to resource needs and subsequently report them with recognizable behaviors offers new insights into their foraging adaptability, and provides a model for further dissection of olfactory learning related processes.     

Oligodendrocyte Progenitor Cells Become Regionally Diverse and Heterogeneous with Age

1. Download high-res image (185KB)
2. Download full-size image

     

基干鲸类的多样性及其与中兽和偶蹄类的系统关系(英文)

在鲸类的演化历史中,由陆生动物转化成完全的水生动物的过程是一个由来已久的演化谜题。基干鲸类的多样性很高,化石记录也很完整。5个科一级的基干鲸类演化支系组成一个并系类群,包括:巴基鲸科(Pakicetidae)、游走鲸科(Ambulocetidae)、雷明顿鲸科(Remingtonocetidae)、原鲸科(Protocetidae)和龙王鲸科(Basilosauridae)。最基干的鲸类巴基鲸科动物可能是一种半水生动物,生活在接近淡水的环境中,代表了陆生偶蹄类向水生鲸类演化的初始一步。更为进步的游走鲸类具有更多适应于水生生活的特征,而且可能更加适应于海水环境。雷明顿鲸类的平衡觉器官和声音传导机制已经表现出向现代鲸类方向演化的趋势。基于稳定氧同位素分析的研究表明,雷明顿鲸类可能完全是海生的。原鲸类的多样性非常高,是鲸类中最先实现全球分布的类群。原鲸保留有发育良好的后肢,但是它们的髂骶关节很松甚至消失。龙王鲸类是鲸类冠类群的绝灭姊妹群。鲸类与其他哺乳动物的系统关系一直存在争议,分子生物学、古生物学和形态学证据都支持鲸类与偶蹄类的亲缘关系较近,但是流行的河马-鲸类亲缘假说尚缺乏坚实的古生物学和形态学数据支持。对石炭兽类和狶类开展详细的系统分析和研究,将有助于厘清河马-鲸类亲缘假说中的不确定关系。如果不使用分子数据来限定现代鲸类和偶蹄类的系统位置,仅使用古生物学和形态学数据的分析仍然支持传统的中兽-鲸类亲缘假说。