Bunias Orientalis Research Articles

Development of Mamestra brassicae and its solitary endoparasitoid Microplitis mediator on two populations of the invasive weed Bunias orientalis

AbstractThe warty cabbage Bunias orientalis is an invasive pest in much of central Europe, including much of Germany since the 1980s, whereas in other countries, such as The Netherlands, it is a less common exotic species. Here, healthy larvae of Mamestra brassicae, which has been found feeding on B. orientalis plants in Germany, and larvae parasitized by one of its major larval endoparasitoids Microplitis mediator, were reared on both herbivore‐induced and noninduced leaves of B. orientalis originating from single large populations growing in The Netherlands and central Germany. Herbivore performance was less negatively affected than parasitoid performance by differences in plant quality. Development times in both M. brassicae and Mi. mediator were shorter on Dutch than German plants and also shorter on noninduced than induced plants. Moreover, survival and body size of the parasitoid was more strongly affected by plant population and induction than survival of healthy M. brassicae. Chemical analyses of defensive secondary metabolites [glucosinolates (GS)] revealed that concentrations of the major GS sinalbin were constitutively expressed in German plants whereas they were induced in Dutch plants. However, in separate feeding bioassays in which preference for induced and noninduced leaves was compared separately, L3 instars of M. brassicae preferred noninduced German plants over Dutch plants but induced Dutch plants over German plants, revealing that changes in primary metabolites or an unidentified non‐GS compound mediates population‐related differences in plant quality. The results reveal asymmetric effects of plant quality in exotic plants on organisms in the second and third trophic level.

Новые и редкие адвентивные растения из Кыргызстана и Узбекистана

New data on the distribution of miscellaneous alien plants in Kyrgyzstan and Uzbekistan are presented. Five species are recorded for the first time from Middle Asia as well: Cerastium nemorale Bieb., Hesperis pycnotricha Borb. et Degen, Viola prionantha Bunge, Rorippa austriaca (Crantz) Bess., Carduus acanthoides L. One species is new to Kyrgyzstan and Uzbekistan: Spergularia rubra (L.) J. et С Presl. Two species are found as new to Kyrgyzstan: Bunias orientalis L., Bidens frondosa L. New localities of 2 species, Cardaria draba (L.) Desv. and Ambrosia artemisifolia L., are discovered in Kyrgyzstan.

Ecological fits, mis-fits and lotteries involving insect herbivores on the invasive plant, Bunias orientalis

Exotic plants bring with them traits that evolved elsewhere into their new ranges. These traits may make them unattractive or even toxic to native herbivores, or vice versa. Here, interactions between two species of specialist (Pieris rapae and P. brassicae) and two species of generalist (Spodoptera exigua and Mamestra brassicae) insect herbivores were examined on two native crucifer species in the Netherlands, Brassica nigra and Sinapis arvensis, and an exotic, Bunias orientalis. Bu. orientalis originates in eastern Europe and western Asia but is now an invasive pest in many countries in central Europe. P. rapae, P. brassicae and S. exigua performed very poorly on Bu. orientalis, with close to 100% of larvae failing to pupate, whereas survival was much higher on the native plants. In choice experiments, the pierid butterflies preferred to oviposit on the native plants. Alternatively, M. brassicae developed very poorly on the native plants but thrived on Bu. orientalis. Further assays with a German Bu. orientalis population also showed that several specialist and generalist herbivores performed very poorly on this plant, with the exception of Spodoptera littoralis and M. brassicae. Bu. orientalis produced higher levels of secondary plant compounds (glucosinolates) than B. nigra but not S. arvensis but these do not appear to be important factors for herbivore development. Our results suggest that Bu. orientalis is a potential demographic ‘trap’ for some herbivores, such as pierid butterflies. However, through the effects of an evolutionary ‘lottery’, M. brassicae has found its way through the plant’s chemical ‘minefield’.

Differing acceptance of familiar and unfamiliar plant species by an oligophagous beetle

AbstractThe mustard leaf beetle, Phaedon cochleariae (F.) (Coleoptera: Chrysomelidae), is specialized to feed and develop on various species within the Brassicaceae. In this study, we investigated the acceptance of several host plant species (Brassica rapa L. and Sinapis alba L.), commonly used by the beetle (familiar plants), and of various unfamiliar plants, including systematically and chemically related [Bunias orientalis L. (Brassicaceae) and Tropaeolum majus L. (Tropaeolaceae), both Brassicales], as well as unrelated non‐host plant species [Plantago lanceolata L. (Plantaginaceae); Lamiales]. Emphasis was laid on the acceptance of the neophyte B. orientalis, and on underlying cues responsible for the acceptance of the various species. Behavioural responses to plant volatiles were studied using a static four‐chamber olfactometer. Stimulants and deterrents were investigated by bioassay‐guided solid phase extraction and semi‐preparative high performance liquid chromatography. A difference in acceptance of plant species was found: odours and polar compounds of all Brassicales evoked attraction and feeding stimulation, respectively, in Ph. cochleariae. Glucosinolates and their volatile hydrolysis products could be the main compounds that are involved in attraction of the beetles. In contrast, Ph. cochleariae did not respond to odours of the non‐host P. lanceolata, and some fractions of this plant had feeding‐deterrent effects, due to the presence of iridoid glycosides, among others. Although adult females accepted the neophyte B. orientalis for oviposition, neonate larvae did not survive on it. The flavonoid‐containing fraction of this plant was deterrent, whereas a similar fraction had been shown to cause some feeding stimulation when derived from S. alba. Differences in qualitative and quantitative composition of related metabolites lead to differentiated plant acceptance, proving the complexity of plant cues and of insect responses that determine host acceptance behaviour. The possibility of a diet breadth enlargement to B. orientalis and the role of Ph. cochleariae as a putative native biocontrol agent of this invasive plant are discussed.

Role of glucosinolates in plant invasiveness

Many plants have been intentionally or accidentally introduced to new habitats where some of them now cause major ecological and economic threats to natural and agricultural ecosystems. The potential to become invasive might depend on plant characteristics, as well as on specific interactions with other organisms acting as symbionts or antagonists, including other plants, microbes, herbivores, or pollinators. The invasion potential furthermore depends on abiotic conditions in the habitat. Several species of the Brassicaceae, well known for their glucosinolate–myrosinase defence system, are invasive species. Various factors are reviewed here that might explain why these species were so successful in colonising new areas. Specific emphasis is laid on the role of glucosinolates and their hydrolysis products in the invasion potential. This particular defence system is involved specifically in plant–plant, plant–microbe and plant–insect interactions. Most research has been done on the mechanisms underlying invasion success of Alliaria petiolata and Brassica spp., followed by Bunias orientalis and Lepidium draba. Some examples are also given for plants that are not necessarily considered as invasives, but which were well investigated with respect to their interference potential with their biotic environment. For each species, most likely a combination of different plant characteristics enhanced the competitive abilities and led to diverse invasive phenotypes.

Ontogenic Profiling of Glucosinolates, Flavonoids, and Other Secondary Metabolites in Eruca sativa (Salad Rocket), Diplotaxis erucoides (Wall Rocket), Diplotaxis tenuifolia (Wild Rocket), and Bunias orientalis (Turkish Rocket)

As an influence of the Mediterranean diet, rocket species such as Eruca sativa L., Diplotaxis species, and Bunias orientalis L. are eaten all over the world at different ontogenic stages in salads and soups. They are all species within the plant order Capparales (glucosinolate-containing species), and all are from the family Brassicaceae. Predominantly, the leaves of these species are eaten raw or cooked, although Eruca flowers are also consumed. There is considerable potential with raw plant material for a higher exposure to bioactive phytochemicals such as glucosinolates, their hydrolysis products, and also phenolics, flavonoids, and vitamins such as vitamin C. These compounds are susceptible to ontogenic variation, and the few published studies that have addressed this topic have been inconsistent. Thus, an ontogenic study was performed and all samples were analyzed using a previously developed robust liquid chromatography/mass spectrometry method for the identification and quantification of the major phytochemicals in all tissues of the rocket species. Seeds and roots of both Eruca and Diplotaxis contained predominantly 4-methylthiobutylglucosinolate. Leaves of Eruca and Diplotaxis contained high amounts of 4-mercaptobutylglucosinolate with lower levels of 4-methylthiobutlyglucosinolate and 4-methylsulfinylbutylglucosinolate. Flowers of Eruca and Diplotaxiscontained predominantly 4-methylsulfinylbutyl-glucosinolate. In addition, roots of both Diplotaxisspecies contained 4-hydroxybenzylglucosinolate but 4-hydroxybenzylglucosinolate was absent from roots of Eruca. Seeds and seedlings of all Eruca contained N-heterocyclic compounds but no sinapine, whereas Diplotaxis contained sinapine but not the N-heterocycles. In all tissues of B. orientalis, 4-hydroxybenzylglucosinolate and 4-methylsulfinyl-3-butenylglucosinolate were predominant. All rocket tissues, except roots, contained significant levels of polyglycosylated flavonoids, with/without hydroxycinnamoyl acylation. The core aglycones were kaempferol, quercetin, and isorhamnetin. The exception was B. orientalis, which had a negligible seed flavonoid content as compared with the other species. Anthocyanins were only detected in Eruca flowers and consisted of a complex pattern of at least 16 different anthocyanins.

Variation in growth pattern and response to slug damage among native and invasive provenances of four perennial Brassicaceae species

Summary The EICA (evolution of increased competitive ability) hypothesis suggests that release from natural enemies and pathogens results in higher vigour of invasive plants as a result of the selection of less defended but rapidly growing genotypes. Slug diversity and abundance appear to be low in North America compared with Europe, and we therefore hypothesized that release from slug herbivory contributes to the invasiveness of European Brassicaceae species in North America. In common garden and glasshouse experiments we compared life history and fitness parameters in native (NP) and introduced (IP) provenances of four invasive Brassicaceae species (Barbarea vulgaris, Bunias orientalis, Cardaria draba, Rorippa austriaca) that were subjected to herbivory by Arion lusitanicus. In climate chamber bioassays we investigated slug damage to seedlings and leaf discs using the same sources of plant material. In all species except B. orientalis we found significant but not always consistent differences in growth and reproductive characteristics between IP and NP plants. Plants of B. vulgaris and R. austriaca from the introduced range had a considerably higher growth rate than those from the native range. While IP plants of the non‐clonal B. vulgaris allocated more resources to seed production than NP plants, the IP plants of the clonal R. austriaca showed a decreased number of seeds. Contrary to expectation, there were no differences between NP plants and IP plants in the number of damaged leaves and leaf area consumed by slugs, or in the proportion of seedlings damaged and killed. Nor were there interaction effects between slug treatments and provenance. The results suggest that there are genetically based differences in growth and reproductive parameters between NP and IP plants. As there were no differences in herbivore damage between the provenances, this genetic differentiation is probably due to factors such as competition rather than herbivore effects. In order to make progress in understanding why some species become invasive, more comparative experimental studies are needed that investigate how different kinds of antagonists (generalist and specialist herbivores and pathogens) influence the performance of plants at different life stages.

Shifts in dominance of native and invasive plants in experimental patches of vegetation

Abstract While it is widely accepted that disturbance often promotes the process of plant invasion, few data are available on specific relationships between different types of disturbance and success of plant invaders. Nor is much known about variation in invader behaviour in response to changing composition of the dominant native species in the recipient habitats. In the middle Main valley near Wurzburg (Germany), two invasive Brassicaceae forbs, Bunias orientalis and Rorippa austriaca , are frequently associated with a small number of dominant native species in the herbaceous vegetation of productive, disturbed sites. Variation in the relative dominance of these species suggests high variability between sites in the factors influencing the local invasion process. In our study, we examined variation in regeneration mode, type and frequency of disturbance, and native species composition, and considered life history differences between the two invasive species as factors contributing to the distinct dominance patterns. These factors were tested in a controlled field experiment in which individuals of the two invasive species and four native species were grown in mixed stands for almost 3 years. The development of the plants was monitored by cover values and all plants were harvested at the end of the study. All factors investigated contributed considerably to the development of distinct dominance patterns in the species mixtures. Relative to the natives, both invasive species were promoted by regeneration from vegetative fragments as compared to development from sexual offspring. While both invasive species were generally promoted by disturbance relative to the natives, they differed in their response to distinct types of disturbance, and these differences were strongly affected by species composition. Our results indicate that invasion success of R. austriaca may depend more on soil disturbance, soil transport and deposition, while B. orientalis is expected to particularly expand at mown sites that do not have dense cover by meadow grasses. Whether the native resident vegetation is mainly composed of successional competitors that suffer from disturbance or of ruderal competitors that compete early and strongly with the invasive species may be of critical importance for invasion by the two species.

Zur Bedeutung der invasiven Kreuzblütler-Art Bunias orientalis (Brassicaceae) als Nektarquelle für mitteleuropäische Insekten

The Turkish warty cabbage (or Russian old man) Bunias orientalis (Linnaeus 1753) is an extremely succcesful invasive plant species, which has firmly established itself in many central European habitats, and is rapidly expanding. For the first time, the nectar production and pollinators of this plant species are described, in order to predict its value as a food source for native insects. In addition, this study aims to predict possible competitive interactions with native plants in the context of pollination. It was found that nectar production per flower in B. orientalis is relatively low. However, because of the extremely high number of flowers per plant and per area, this plant is a valuable food source for energetically demanding visitors such as bumble bees and honeybees. These are the most common visitors to B orientalis, even though classical pollination syndromes would categorise this flower as fly-pollinated. Since B orientalis is an attractive nectar source, it is conceivable that there is a negative impact of its presence on the fitness of native species, simply by depressing visitation frequencies to other species.

Sorption and transport of radionuclides by tumbleweeds from two plastic-lined radioactive waste ponds

Previous research has examined the uptake of radionuclides by tumbleweeds growing in contaminated soils, but none has heretofore examined the sorption of radionuclides to tumbleweeds blowing into radioactively contaminated water. Three tumbleweed species; Russian thistle ( Salsola kali), Jim Hill mustard ( Sisymbrium altissimum) and summer cypress ( Kochia scoparia) blow in, and out of, two plastic-lined radioactive wastewater ponds, constructed in 1993 on the US Department of Energy's Idaho National Engineering and Environmental Laboratory in southeast Idaho. This research quantified radionuclide sorption to tumbleweeds, tumbleweed movement from the ponds, and determined radionuclide transport from the ponds. Average plant/water concentration factors associated with tumbleweeds taken from the ponds ranged from 5 for 152Eu to over 9000 for 54Mn. Based on changes in tumbleweed numbers and average concentrations associated with them, 66.2 MBq were estimated to have been transported from the ponds via tumbleweeds between 18 October 1994 and 8 November 1996. This amounts to about 0.01% of the non-tritium and 0.0002% of the tritium activity released to the ponds through 8 November 1996. A power function best described the radionuclide buildup curve for tumbleweeds submerged in the ponds. Visually marked tumbleweeds traveled from the ponds in the predominant wind direction a maximum of 737 m. Management practices which may reduce the number of tumbleweeds blowing both into and out of contaminated ponds are discussed.

Leaf Phenology and Seasonal Carbon Gain in the Invasive Plant, Bunias orientalis L.

: In two potentially competing herbaceous plants, the invasive Bunias orientalis L. (Brassicaceae) and the native Picris hieracioides L. (Asteraceae), seasonal changes in leaf CO2 gas exchange and plant growth were studied over an entire growing season from February 1998 to December 1998 in two experimental fields. The study was motivated by the hypothesis that pre-adaptive phenological displacement of alien species relative to the native flora may be an important reason for the observed expansion of B. orientalis in central Europe. We quantified the importance of phenological differences for annual carbon gain in both species by estimating total leaf carbon gain from the results of leaf CO2 exchange and changes in plant leaf area. Bunias orientalis achieved almost half of its annual carbon gain in the time between early September and December, when competition for light by other species, like P. hieracioides, is low. Our quantitative approach corroborates the notion that the phenological shift of a relatively poor competitor, such as B. orientalis, could be of great importance for the success as an invasive species.

Establishment of the invasive perennial herb Bunias orientalis L.: An experimental approach

Abstract A 2-year field experiment was performed to assess regeneration, establishment and growth of the invasive polycarpic perennial Brassicaceae Bunias orientalis L. from transplanted juveniles and propagules (seeds, fruits and root fragments). Further treatments were: different planting depths of the propagules, different root fragment sizes and a varied competition intensity by the matrix vegetation. In contrast to a high number of individuals established from planted juveniles (ca. 90 %), only relatively few propagules gave rise to seedlings or regenerating plants (0–16 %). However, upon emergence, all plants showed low mortality. Although the number of regenerated or recruited plants was affected by all treatments, only one treatment level (the use of very small root fragments of 1 cm length) completely failed in establishing plants. Plants experiencing low competition intensity attained high aboveground performance and reproductive output as well as reproductive success within two growth periods. Under high competition intensity recruitment, regeneration and growth were strongly negatively affected. The high morphological plasticity of rosette growth of B. orientalis seems to be advantageous for persistence in such situations. The results show that young B. orientalis plants are robust and can efficiently sequester and translate elevated resources into rapid growth and early reproductive output although the species is a rather long-lived iteroparous perennial. In addition, population foundation or regeneration can be based on both seeds and root fragments, even when buried under a thick soil layer. This seems to be a very efficient adaption to habitats which are subject to anthropogenic soil perturbations.

Demographic and genetic invasion history of a 9-year-old roadside population of Bunias orientalis L. (Brassicaceae).

The population history of a 9-year-old roadside population of the invasive plant Bunias orientalis was reconstructed by demographic analysis including size, position, age (determined by herbchronology) and RAPD-PCR patterns of individual plants. We evaluated emerging patterns of population growth and genetic structure during a full period of population development under typical site conditions (anthropogenic disturbance) and their possible consequences for the invasion potential of the species. The population has grown rapidly and continuously (though with slowing geometric population increase) during the 9 years since its foundation, filling the space available in the study area. Genetic variation (RAPD markers) was already high in the founder cohorts and remained at the same level throughout population development (variance fluctuations <15%). Both results may be related to the mowing management at the site which seems to promote population growth of B. orientalis relative to other co-occuring species and to prevent the genetic drift and the development of spatial genetic structure that would be expected under isolation-by-distance models. Large founder plants had comparatively low genetic variance and were more closely related to younger cohorts than were small founder plants, indicating that selection acted during population development. Overall, the current anthropogenic disturbance regimes may contribute to high genetic variability by artificially increasing gene flow and thereby promoting the adaptability of invasive species to the often unpredictable conditions at disturbed sites. Our approach using retrospective demographic investigation allows the detection of spatio-temporal microscale patterns in genetic and phenotypic variation. Thus it allows a thorough understanding of local invasions of perennial herbaceous plants.

The role of growth form and correlated traits in competitive ranking of six perennial ruderal plant species grown in unbalanced mixtures

The competitive abilities of six perennial ruderal plants of three different growth forms were compared via yield measures using an additive diallel experimental design with unbalanced mixtures (9:3 or 3:9 plants per pot, respectively). Thus, in a given mixture species A was grown in two configurations: three individuals in centre position of the pot together with nine plants of species B in border position and vice versa. Effect competitive abilities as well as response competitive abilities of the species were significantly related to canopy height and plant biomass. The species with lower rosette growth form and smaller biomasses were weaker competitors than the species possessing elevated canopies along with higher biomasses, whereas total leaf area was not significantly correlated with competitive ability between species. Species differences in competitive ability were stronger between the plants grown in the central position than between those grown in the border position. Furthermore, interactions between species-specific traits and configuration could be observed, indicating the importance of species proportions and arrangement patterns for evaluation of competitive outcome in the field. The degree of complete transitivity of the competitive network of the six ruderal species, which was significantly higher than expected under the null model in our experimental design, also seemed to depend on species proportions in mixture. Shifts in root:shoot ratio of the centre plants when faced with competition by the border plants were in the direction of higher shoot allocation for the weak competitors with rosette growth form irrespective of the neighbour species, except for Bunias orientalis , which showed a more plastic response. The stronger competitors showed higher root allocation ( Urtica dioica ) or were hardly affected at all. Consistent with the results of our experiment, the weaker competitors occur at rather frequently disturbed and therefore transient field sites whereas the stronger competitors predominate at infrequently disturbed sites during several phases of succession.

Phenological shifts of the alien colonizer Bunias orientalis: Image‐based analysis of temporal niche separation

Abstract. Phenological development of the colonizer Bunias orientalis L. was investigated in permanent plots in herbaceous vegetation, using photography and image analysis. In all habitats but one, B. orientalis showed a two‐phased rosette growth behaviour, with a first peak cover reached in spring, roughly coinciding with an early peak cover of the matrix vegetation, and a second autumn growth flush occurring in a phase of reduced matrix vegetation cover. This seasonally bimodal growth pattern of B. orientalis appears to partly compensate for its competitive inferiority in crowded herbaceous vegetation. Small or overshadowed individuals of this species particularly profit from higher above‐ground performance or release from overlap in autumn. The significance of temporal niche separation for survival and growth of B. orientalis individuals varies with habitat conditions, being most apparent in occasionally disturbed habitats with a relatively low frequency of gap formation. Despite some limitations, image analysis proved to be useful for phenological investigations within herbaceous plant stands.

Growth patterns of the alien perennial Bunias orientalis L. (Brassicaceae) underlying its rising dominance in some native plant assemblages

The polycarpic perennial Bunias orientalis L. (Brassicaceae) introduced to Central Europe in the 18th century recently entered a phase of rapid spread accompanied by sudden establishments of extensive dominance stands mainly on roadside locations. We studied vegetation structure and expansion rate of B. orientalis stands and performed a series of experiments to investigate key factors that underlie the colonizing and establishment of B. orientalis. Reiterated observations exposed a high current expansion rate of B. orientalis populations and vegetation surveys of B. orientalis stands showed that these stands were mainly composed of Artemisietea and Arrhenateretea species. Regeneration experiments with root fragments revealed high regeneration capacities: root fragments of 3 cm length showed 93% regeneration, varying water content (10–50% water loss) and separation into root cortex and root stele yielded regeneration of 30 to 50%. In a field study high regrowth after mowing with varying mowing intensity indicates B. orientalis to be well adapted to disturbed sites as its preferential locations for development of dominance stands. Vegetative growth parameters were studied in two controlled growth experiments with elevated nutrient availabilities. B. orientalis exhibited a high sensitivity to nutrient addition and rosette sizes of maximal 90 cm were reached. Biomass was comparable or even higher than that of native ruderals grown in the same experiment. Measurements of reproductive parameters revealed a high reproductive effort (0.2 to 0.45 g g-1) even under intense mowing regimes, resulting in a dense seed bank with maximal values of about 400 fruits (≅550 seeds) l-1 soil. With respect to colonization and establishment of B. orientalis the results of our study enable the formulation of three hypotheses.

Phytotoxic constituents from Bunias orientalis leaves

Aqueous extracts of Bunias orientalis leaves showed considerable germination inhibition in petri-dish bioassays. As major B. orientalis leaf constituents with known allelopathic activity bound forms of p-coumaric, ferulic and sinapic acids as well as two C 13-norisoprenoids, i.e. 3-hydroxy-β-ionone and 3-hydroxy-5,6-epoxy-β-ionone, were identified in XAD-2 isolates. After separation of the glycosidic isolate by counter-current chromatography/HPLC, 3-hydroxy-5,6-epoxy-β-ionyl-β- d-glucoside and the glucose ester of sinapic acid were isolated in pure form and their structures elucidated from 1H and 13C NMR spectral data. The corresponding aglycones were found to be major constituents in leaf leachate solutions of B. orientalis, together with the known allelochemic loliolide.

The cryptopolyploidy (Jaretzky 1928: «verkappte Polyploidie»; Chiarugi 1933: «criptopoliploidia»; Melinossi 1935, 1937: «duplicazione endocromosomica»). A terminological criticism.

Abstract In the cytological literature and text-books, the term cryptopolyploidy is mainly ignored and sometimes re-interpreted and often wrongly quoted from the point of view of historical accuracy. The paternity over this term should be ascribed to Chiarugi (1933), although Jaretzky (1928a, b), while investigating karyologically two species of the genus Bunias, B. orientalis and B. erucago, first advanced a concept of «verkappte Polyploidie» to indicate the occurrence of chromosomes of enlarged size hypothetically due to fusion of homologous members (Jaretzky's «Sammelchromosomen»). By such homologous chromosome fusion a polyploid karyotype could appear as a diploid karyotype. A pupil of Chiarugi, Roma Melinossi, reinvestigating the two species quoted by Jaretzky, Bunias orientalis and B. erucago, documented a quite different karyological state for these species, cf. Melinossi (1935, 1937), that is the presence of the same karyotype (2n=14) in both species and the occurrence of chromosome of doubled siz...

2-(2-Butenylidene)-3,3-dimethyl-5-(2-oxopropyl)tetrahydrofuran: A New Degradation Product of 3-Hydroxy-5,6-epoxy-.beta.-ionol

Identification of 2-(2-butenylidene)-3,3-dimethyl-5-(2-oxopropyl)tetrahydrofuran diastereomers (4, 5) in various leaves [stinging nettle; sloe tree; strawberry; vine (Riesling); sweet silique (Bunias orientalis)] was achieved by comparison of HRGC retention and spectral (MS; vapor phase FTIR) data with those of synthetic references. Model experiments revealed their acid-catalyzed formation from 3-hydroxy-5,6-epoxy-β-ionol that was present in glycosidically bound form in the above-mentioned leaves. Assignment of the isomers 4a/4b and 5a/5b was established by NOE experiments. Enantiodifferentiation carried out by on-line coupled multidimensional gas chromatography-mass spectrometry revealed the occurrence of enantiomerically pure 5S enantiomers 4b/5b in the natural sources

Diets of the Black-Tailed Hare in Steppe Vegetation

Highlight: Thirteen species of plants were identified in fecal pellets of black-tailed hares collected from sagebrush and bitterbrush communities in southcentral Washington. Microscopic analysis of plant fragments indicated that yarrow was the most common food item in the diet, making up 25% of the overall diet. Other food items in decreasing order of importance were: turpentine cymopterus > hoary aster > needleandthread > and Jim Hill mustard. Preference indices indicated that needleandthread was the most preferred plant in the sagebrush community, while yarrow was the most preferred plant in the bitterbrush community. Although the communities were not similar in plant species frequency of Occurrence and cover, the hare diets were quite similar in both communities, indicating that hares were actively seeking preferred foods. Black-tailed hares (jackrabbits), Lepus californicus, are important herbivores on rangelands throughout the central and western United States (Hall and Kelson 1959). On many rangelands they can compete for forage with livestock and other wildlife. Hansen and Flinders (1969) have reviewed the known dietary habits of hares in North America. The objective of this investigation was to determine the dietary habits of black-tailed hares within sagebrush (Artemisia tridentata) and bitterbrush (Purshia tridentata) communities in southcentral Washington. The communities are utilized to some extent by mule deer (Odocoileus hemionus) and small mammals such as the ground squirrel (Spermophilus townsendi) but have not been grazed by livestock since 1943.