Comparison of <Emphasis Type="Italic">Claviceps purpurea</Emphasis> populations originated from experimental plots or fields of rye

Background  

The phytopathogenic ascomycete Claviceps purpurea causes the ergot — serious disease of rye and grasses. Its sclerotia containing toxic ergot alkaloids decrease a quality of cereal grain. The fungus infects young, unfertilized ovaries of the hosts. Due to the very short time in which infection can occur, growth rate of mycelium can play some role in the infection process. Resistance genes to C. purpurea have not been found so far.     

Observations on the prevalence and incidence of ergot disease in Great Britain with special reference to open-flowering male-sterile cereals

Ergot (Claviceps purpurea) of grasses is prevalent throughout Britain. The disease also occurs regularly in most cereal varieties but generally is of low incidence. Incidence is much greater in open-flowering and male-sterile cereals, with the infection seeming to come, initially, from the large reservoir of inoculum amongst grasses. The production of F₁-hybrid cereal seed, which necessitates the use of male-sterile lines, could therefore be jeopardised.     

甘肃马先蒿不同寄生密度对紫花针茅内生真菌共生体生理特性的影响

【目的】根寄生植物持续掠夺禾草体内营养物质成为禾草生长过程中的生物逆境,禾草内生真菌提高冷季型禾草对生物和非生物逆境耐受能力。然而,有关禾草内生真菌对根寄生逆境下禾草生理过程调控作用的研究鲜有报道。【方法】开展温室盆栽试验,以带菌(E+)和不带菌(E-)紫花针茅为研究对象,研究甘肃马先蒿不同寄生密度对紫花针茅抗氧化酶活性、渗透调节物质和根系活力影响的动态变化规律。【结果】甘肃马先蒿寄生显著增加紫花针茅抗氧化酶活性、丙二醛和脯氨酸含量,而根系活力却快速降低;高密度寄生紫花针茅植株生理特性指标显著高于低密度寄生或自然生长植株;同时,E+紫花针茅抗氧化酶活性、脯氨酸含量和根系活力显著高于E-植株,而E-植株丙二醛含量显著高于E+植株。【结论】禾草内生真菌通过增强抗氧化酶活性、调节细胞膜透性和增强根系生长能力的途径提高紫花针茅对根寄生逆境的耐受能力,利用植物替代方法带菌紫花针茅可以作为一种生物防治手段用于防控根寄生杂草。     

Family issues: fungal endophyte protects host grass from the closely related pathogen Claviceps purpurea

Certain cool season grasses establish systemic and asymptomatic symbioses with clavicipitaceous fungi of the genus Neotyphodium, which affect multiple biotic interactions within host neighborhood. The presumed symbiont-mediated plant resistance to pathogens is mostly based on studies performed under laboratory and greenhouse conditions. Here we investigated, in two outdoor experiments, the relation between two fungi of the same family with opposite effects on Lolium multiflorum plants: the mutualist endophyte Neotyphodium occultans, and the pathogen Claviceps purpurea. Natural infection and its consequences on symbiotic and non-symbiotic plants were studied under varying conditions of stress by herbicide. In both experiments, N. occultans reduced significantly the infection by C. purpurea at population levels (70 % less). The percentage of spikes infected by C. purpurea was almost three times lower in endophyte-symbiotic plants than in non-symbiotic ones. However, the protective effect was not maintained under stress condition. Our results show that constitutive symbionts such as the systemic fungal endophytes mediate the interaction between host grasses and pathogens, although the effect may depend on the level of stress in the environment.     

Lumi-ergometrine – structural identification and occurrence in sclerotia

The fungus Claviceps purpurea grows on grasses and cereal grains and produces six predominant ergot alkaloids. These toxic substances undergo different transformation reactions during storage and cereal processing. One of these reactions is the addition of water to a double bond in the ergoline skeleton. Since light is required for this process, the substances formed were named lumi-ergot alkaloids. From these, a new asymmetric carbon and consequently two epimers with different polarities are formed. For investigations of lumi-ergot alkaloids, ergometrine was used exemplarily as it represents one of the six ergot alkaloids predominantly formed by Claviceps purpurea. The main reaction product, the less polar compound of the two lumi-ergometrine epimers, was separated by HPLC and unambiguously identified as 10-(S)-lumi-ergometrine using X-ray structural analysis. A HPLC-MS/MS method was developed for the detection of this substance in sclerotia extracts. Using this method, the existence of both epimeric forms of lumi-ergometrine could be proved in the sclerotia. This is the first time that the existence of a lumi-transformation product of ergot alkaloids was proved in naturally grown samples.     

甘肃马先蒿寄生对禾草内生真菌共生体光合特性的影响

[目的]甘肃马先蒿与感染内生真菌的禾草(紫花针茅和麦宾草)建立根寄生关系,有关内生真菌对根寄生危害禾草光合作用调控方面的研究较少。[方法]本研究以紫花针茅和麦宾草带菌(E+)、不带菌(E-)植株为研究对象,研究甘肃马先蒿寄生和未寄生处理对紫花针茅和麦宾草E+、E-植株不同生长阶段光合特性影响的动态变化。[结果]甘肃马先蒿寄生显著降低紫花针茅和麦宾草的净光合速率、蒸腾速率和气孔导度,而胞间二氧化碳浓度和水分利用率却显著增加,这与禾草是否感染内生真菌无关。甘肃马先蒿寄生后E+紫花针茅的净光合速率、气孔导度和蒸腾速率高于E-植株,而麦宾草E+植株的净光合速率、气孔导度和蒸腾速率却低于E-植株;同时,根寄生条件下E+紫花针茅的胞间二氧化碳浓度和水分利用率低于E-植株;而E-麦宾草植株的胞间二氧化碳浓度和水分利用率却低于E+植株。[结论]内生真菌侵染影响甘肃马先蒿根寄生危害禾草的光合作用;甘肃马先蒿和内生真菌同时成为禾草营养消耗库时,内生真菌与禾草的共生关系处于一种互惠共生和相互拮抗的动态变化。     

Shading by Napier Grass Reduces Malaria Vector Larvae in Natural Habitats in Western Kenya Highlands

Increased human population in the Western Kenya highlands has led to reclamation of natural swamps resulting in the creation of habitats suitable for the breeding of Anopheles gambiae, the major malaria vector in the region. Here we report on a study to restore the reclaimed swamp and reverse its suitability as a habitat for malaria vectors. Napier grass-shaded and non-shaded water channels in reclaimed sites in Western Kenya highlands were studied for the presence and density of mosquito larvae, mosquito species composition, and daily variation in water temperature. Shading was associated with 75.5% and 88.4% (P < 0.0001) reduction in anopheline larvae densities and 78.1% and 88% (P < 0.0001) reduction in Anopheles gambiae sensu lato (s.l.) densities in two sites, respectively. Shading was associated with a 5.7°C, 5.0°C, and 4.7°C, and 1.6°C, 3.9°C, and 2.8°C (for maximum, minimum, and average temperatures, respectively) reduction (P < 0.0001) in water temperatures in the two locations, respectively. An. gambiae s.l. was the dominant species, constituting 83.2% and 73.1%, and 44.5% and 42.3%, of anophelines in non-shaded and shaded channels, respectively, in the two sites, respectively. An. gambiae sensu stricto (s.s.) constituted the majority (97.4%) of An. gambiae s.l., while the rest (2.6%) comprised of Anopheles arabiensis. Minimum water temperature decreased with increasing grass height (P = 0.0039 and P = 0.0415 for Lunyerere and Emutete sites, respectively). The results demonstrate how simple environmental strategies can have a strong impact on vector densities.     

Population structure of Spodoptera frugiperda maize and rice host forms in South America: are they host strains?

Determining which factors contribute to the formation and maintenance of genetic divergence to evaluate their relative importance as a cause of biological differentiation is among the major challenges in evolutionary biology. In Spodoptera frugiperda (Smith) (Lepidoptera: Noctuidae) two host strains have been recognized in the 1980s: the corn‐strain prefers maize, sorghum, and cotton, whereas the rice‐strain prefers rice and wild grasses. However, it is not clear to what extent these so‐called ‘strains’, which have also been called ‘host races’ or even ‘sibling species’, are really associated with host plants. Due to the indeterminate evolutionary status, we will use the term ‘host forms’ (sensu Funk). Here, we characterized populations collected from maize, rice, and wild grasses from three countries in South America. Using two mitochondrial cytochrome oxidase I (mtCOI) markers and 10 polymorphisms in the triose phosphate isomerase (Tpi) gene, we found various patterns of host association. Two hundred twenty‐seven nuclear amplified fragment length polymorphisms (AFLPs) markers revealed significant genetic differentiation among populations, which was generally correlated to the host from which the larvae were collected. Using a multivariate discriminant analysis and a Bayesian clustering approach, we found that individuals could be grouped into 2–5 genetically distinct clusters, depending on the method. Together, our results indicate that although host‐associated differentiation is present in this species, it does not account for all observable genetic variation and other factors must be maintaining genetic differentiation between these forms. Therefore, the term ‘host strains’ should be abandoned and ‘host forms’ should be used instead for S. frugiperda.     

Consumption of cereal leaf beetle,Oulema melanopus,by generalist predators in wheat fields detected by molecular analysis

The cereal leaf beetle (CLB), Oulema melanopus L. (Coleoptera: Chrysomelidae), is a major pest of cereal crops that has recently been reported in western Canada. We developed a set of primers to detect CLB DNA in the gut of six common predator taxa in wheat fields: lady beetles (20 positives of 143 individuals), nabid bugs (73 positives of 206 individuals), and wolf spiders (2 positives of 25 individuals). Nabis americoferus Carayon (Hemiptera: Nabidae) and Coccinella septempunctata L. (Coleoptera: Coccinellidae) were the most abundant predators in cereal fields, with 0.35 and 0.05 proportion of samples positive for CLB DNA, respectively. The prey DNA half-lives were used to adjust the estimates for N. americoferus to 0.22, due to its longer DNA detectability relative to C. septempunctata. Overall, Hippodamia parenthesis (Say) (Coleoptera: Coccinellidae) had the highest proportion of positives at 0.43. There was a positive association between CLB abundance and proportion of N. americoferus and C. septempunctata positives for CLB DNA. This study highlights the contribution of generalist predators to CLB mortality and their important role in integrated management for CLB. Furthermore, we provide a molecular tool that can be used to identify predators of CLB and predation frequency in agricultural fields .     

The higher‐level phylogenetic relationships of the Eumeninae (Insecta,Hymenoptera, Vespidae), with emphasis on Eumenes sensu lato

Cladistic analyses were carried out to infer the phylogenetic relationships among taxa that were originally part of the large genus Eumenes. Terminals belonging to other eumenine lineages were also included, as well as terminals from other vespid subfamilies. Analyses under equal weights and implied weights were carried out, and better results were obtained with the latter. The results corroborated the monophyly of Eumeninae, and recovered Zethini sensu lato as the sister‐lineage to the remaining eumenines. Eumenes sensu lato as originally recognized is paraphyletic relative to Odynerus sensu lato. A natural classification at the tribal level congruent with the phylogenetic results may be proposed, and the names Zethini, Odynerini, and Eumenini are already available. This is the most comprehensive phylogeny of the Eumeninae to date. A new generic synonymy is Alfieria Giordani Soika, 1934 = Delta de Saussure, 1855.     

Genetic structure,ecological versatility,and skull shape differentiation in Arvicola water voles (Rodentia,Cricetidae)

Water voles from the genus Arvicola display an amazing ecological versatility, with aquatic and fossorial populations. The Southern water vole (Arvicola sapidus) is largely accepted as a valid species, as well as the newly described Arvicola persicus. In contrast, the taxonomic status and evolutionary relationships within Arvicola amphibiussensu lato had caused a long-standing debate. The phylogenetic relationships among Arvicola were reconstructed using the mitochondrial cytochrome b gene. Four lineages within A. amphibiuss.l. were identified with good support: Western European, Eurasiatic, Italian, and Turkish lineages. Fossorial and aquatic forms were found together in all well-sampled lineages, evidencing that ecotypes do not correspond to distinct species. However, the Western European lineage mostly includes fossorial forms whereas the Eurasiatic lineage tends to include mostly aquatic forms. A morphometric analysis of skull shape evidenced a convergence of aquatic forms of the Eurasiatic lineage toward the typically aquatic shape of A. sapidus. The fossorial form of the Western European lineage, in contrast, displayed morphological adaptation to tooth-digging behavior, with expanded zygomatic arches and proodont incisors. Fossorial Eurasiatic forms displayed intermediate morphologies. This suggests a plastic component of skull shape variation, combined with a genetic component selected by the dominant ecology in each lineage. Integrating genetic distances and other biological data suggest that the Italian lineage may correspond to an incipient species (Arvicola italicus). The three other lineages most probably correspond to phylogeographic variations of a single species (A. amphibius), encompassing the former A. amphibius, Arvicola terrestris, Arvicola scherman, and Arvicola monticola.     

Exploration of meaningful subspecies definitions of the carnivorous Northern Pitcher Plant (Sarracenia purpurea), throughout its geographic distribution

The carnivorous wetland plant, Sarracenia purpurea (the northern pitcher plant) is native to eastern and Midwestern North America. This species is abundant within its habitat but suitable habitat is increasingly scarce, raising interest in S. purpurea restoration and conservation. Complicating conservation planning, two controversial subspecies of S. purpurea are historically defined primarily on morphologic traits: S. purpurea subsp. purpurea distributed north of Maryland and S. purpurea subsp. venosa distributed south of Maryland. S. purpurea is also found in three distinct habitat types defined by substrate: acidic Sphagnum peatlands, acidic sandy savannahs, and alkaline marl wetlands. In species level studies, S. purpurea leaves have exhibited morphological plasticity in response to environmental variability, bringing into question the validity of subspecies definitions based on morphology alone. This study examined morphologic and genetic variation throughout S. purpurea’s natural distribution, encompassing both the traditional subspecies and three unique habitat types testing the validity of traditional subspecies definitions. Genetic analysis indicated possible ecological significance of considering a new grouping of S. purpurea populations into Midwest, N. East Coast and S. East Coast populations (AMOVA % variation = 13.34, P = 0.0078) based on genetic differentiation. Morphological variation in leaf shape measurements supported this division as well as indicating plasticity associated with environmental variables. This study conservatively suggests that new, geographical area conservation units may be a more important conservation unit for preserving S. purpurea genetic variation and morphological plasticity than traditional subspecies definitions.     

The impact of plant associations on Macrosteles quadrilineatus management in carrots

Habitat diversification can influence the interactions of insects with plants and this can be used in agroecosystems for the management of pest populations. Plant diversification can be achieved through planting crops, such as trap crops, or by adjusting weed management. Aster leafhopper, Macrosteles quadrilineatus Forbes (Hemiptera: Cicadellidae), is a polyphagous species that uses cereals, vegetables, and weeds as host plants. The influence of weeds on M. quadrilineatus abundance was investigated experimentally in carrot [Daucus carota L. cv. Canada (Apiaceae)] field plots by adjusting the level of management of two groups of weeds (broadleaf and grass) and by comparing it to weed‐free plots. The preference of M. quadrilineatus for different cereal and weed species relative to carrots was tested in choice test assays. Habitat context influenced the abundance of M. quadrilineatus in the field experiments. The presence of border crops such as oat, rye, barley, wheat, and triticale did not significantly attract or repel this insect to carrot plots compared to the no‐border treatment. However, spelt‐bordered plots had 42% fewer M. quadrilineatus than three treatments, triticale, wheat, and barley, that had the highest insect abundance. The type of weed management affected M. quadrilineatus abundance in carrot plots, but not the frequency of herbicide application. Plots that had carrot growing with broadleaf‐weeds had about 59% fewer M. quadrilineatus compared with those growing with crabgrass or carrot alone. In the greenhouse choice tests, grasses (e.g., cereals) attracted and broadleaf‐weeds repelled M. quadrilineatus relative to carrots. In summary, carrot growers may be able to manage this pest by reducing the interaction of cereal cover crops with carrots and eliminating grassy weeds in commercial production fields.     

Insect oviposition preference between Epichloë‐symbiotic and Epichloë‐free grasses does not necessarily reflect larval performance

Variation in plant communities is likely to modulate the feeding and oviposition behavior of herbivorous insects, and plant‐associated microbes are largely ignored in this context. Here, we take into account that insects feeding on grasses commonly encounter systemic and vertically transmitted (via seeds) fungal Epichloë endophytes, which are regarded as defensive grass mutualists. Defensive mutualism is primarily attributable to alkaloids of fungal origin. To study the effects of Epichloë on insect behavior and performance, we selected wild tall fescue (Festuca arundinacea) and red fescue (Festuca rubra) as grass–endophyte models. The plants used either harbored the systemic endophyte (E+) or were endophyte‐free (E?). As a model herbivore, we selected the Coenonympha hero butterfly feeding on grasses as larvae. We examined both oviposition and feeding preferences of the herbivore as well as larval performance in relation to the presence of Epichloë endophytes in the plants. Our findings did not clearly support the female's oviposition preference to reflect the performance of her offspring. First, the preference responses depended greatly on the grass–endophyte symbiotum. In F. arundinacea, C. hero females preferred E+ individuals in oviposition‐choice tests, whereas in F. rubra, the endophytes may decrease exploitation, as both C. hero adults and larvae preferred E? grasses. Second, the endophytes had no effect on larval performance. Overall, F. arundinacea was an inferior host for C. hero larvae. However, the attraction of C. hero females to E+ may not be maladaptive if these plants constitute a favorable oviposition substrate for reasons other than the plants' nutritional quality. For example, rougher surface of E+ plant may physically facilitate the attachment of eggs, or the plants offer greater protection from natural enemies. Our results highlight the importance of considering the preference of herbivorous insects in studies involving the endophyte‐symbiotic grasses as host plants.     

Early development and larval behaviour of two clingfishes, <Emphasis Type="Italic">Lepadogaster purpurea</Emphasis> and <Emphasis Type="Italic">Lepadogaster lepadogaster</Emphasis> (Pisces: Gobiesocidae)

The recent revision on the taxonomic status of Lepadogaster lepadogaster resulted in the division of this species into L. lepadogaster and L. purpurea, the clarification of each species’ distribution ranges and the elimination of L. zebrina (now in synonymy with L. lepadogaster). This new taxonomic status led to the need of clarifying the early development of the two species. Embryonic development lasted 21 days in L. purpurea at a mean temperature of 14.2°C, and 16 days in L. lepadogaster at a mean temperature of 16.5°C. Newly hatched larvae of both species measured 5.2 mm, had the mouth and anus opened, pigmented eyes and almost no yolk. At hatching and throughout development the two species can be distinguished by the ventral pigmentation which is absent in L. purpurea. The change to a benthic mode of life was gradual in both species, with larvae increasingly spending more time close to the bottom until definitely settling. Larval development lasted 33 days in L. purpurea at a mean temperature of 14.6°C and 18 days in L. lepadogaster at a mean temperature of 16.5°C. Locomotion and foraging behaviours are described for both species. L. lepadogaster showed a higher frequency of swimming and foraging behaviour when compared with L. purpurea.     

Molecular Phylogeny,Diversity, and Bioprospecting of Endophytic Fungi Associated with wild Ethnomedicinal North American Plant Echinacea purpurea (Asteraceae)

The endophytic fungal community associated with the ethnomedicinal plant Echinacea purpurea was investigated as well as its potential for providing antifungal compounds against plant pathogenic fungi. A total of 233 endophytic fungal isolates were obtained and classified into 42 different taxa of 16 genera, of which Alternaria alternata, Colletotrichum dematium, and Stagonosporopsis sp. 2 are the most frequent colonizers. The extracts of 29 endophytic fungi displayed activities against important phytopathogenic fungi. Eight antifungal extracts were selected for chemical analysis. Forty fatty acids were identified by gas chromatography‐flame‐ionization detection (GC‐FID) analysis. The compounds (–)‐5‐methylmellein and (–)‐(3R)‐8‐hydroxy‐6‐methoxy‐3,5‐dimethyl‐3,4‐dihydroisocoumarin were isolated from Biscogniauxia mediterraneaEPU38CA crude extract. (–)‐5‐Methylmellein showed weak activity against Phomopsis obscurans, P. viticola, and Fusarium oxysporum, and caused growth stimulation of C. fragariae, C. acutatum, C. gloeosporioides, and Botrytis cinerea. (–)‐(3R)‐8‐Hydroxy‐6‐methoxy‐3,5‐dimethyl‐3,4‐dihydroisocoumarin appeared slightly more active in the microtiter environment than 5‐methylmellein. Our results indicate that E. purpurea lives symbiotically with different endophytic fungi, which are able to produce bioactive fatty acids and aromatic compounds active against important phytopathogenic fungi. The detection of the different fatty acids and aromatic compounds produced by the endophytic community associated with wild E. purpurea suggests that it may have intrinsic mutualistic resistance against phytopathogen attacks in its natural environment.     

You stay,but I Hop: Host shifting near and far co‐dominated the evolution of Enchenopa treehoppers

The importance and prevalence of phylogenetic tracking between hosts and dependent organisms caused by co‐evolution and shifting between closely related host species have been debated for decades. Most studies of phylogenetic tracking among phytophagous insects and their host plants have been limited to insects feeding on a narrow range of host species. However, narrow host ranges can confound phylogenetic tracking (phylogenetic tracking hypothesis) with host shifting between hosts of intermediate relationship (intermediate hypothesis). Here, we investigated the evolutionary history of the Enchenopa binotata complex of treehoppers. Each species in this complex has high host fidelity, but the entire complex uses hosts across eight plant orders. The phylogenies of E. binotata were reconstructed to evaluate whether (1) tracking host phylogeny; or (2) shifting between intermediately related host plants better explains the evolutionary history of E. binotata. Our results suggest that E. binotata primarily shifted between both distant and intermediate host plants regardless of host phylogeny and less frequently tracked the phylogeny of their hosts. These findings indicate that phytophagous insects with high host fidelity, such as E. binotata, are capable of adaptation not only to closely related host plants but also to novel hosts, likely with diverse phenology and defense mechanisms.     

Insensitive blueberries: a total‐evidence analysis of Disterigma s.l. (Ericaceae) exploring transformation costs

Disterigma sensu lato (s.l.) is a polyphyletic genus of neotropical blueberries that comprises 37 species found in Central and South America, mostly in Andean cloud forests and páramos. The present phylogenetic analysis, based on molecular and morphological data for 84% of the species of Disterigma s.l., addressed the monophyly of the genus and identified the putative morphological synapomorphies of the main clades. The sensitivity of the phylogenetic hypotheses to the choice of analytical parameters was addressed in detail, by varying all possible parameters and applying different treatments for indel coding. A total of 29 transformation cost matrices were investigated and all these analyses were performed in POY 4, using direct optimization. A diagnosable Disterigma sensu stricto (s.s.) clade was recovered in all analyses, despite changes in the transformation costs. Additionally, none of the analyses refuted the segregation of D. trimerum, D. ulei, D. pentandrum, D. rimbachii, and D. bracteatum from Disterigma s.s. Although measurements of congruence are used to choose among alternative analytical parameter sets, the behaviour of the RILD index (rescaled incongruence length difference) in this study suggested that it may not be a good measure of congruence and that further studies are necessary to better understand its performance. © The Willi Hennig Society 2009.