Invasive Weed (invasive + weed)

Distribution by Scientific Domains

Selected Abstracts

A novel host shift and invaded range of a seed predator, Acanthoscelides macrophthalmus (Coleoptera: Chrysomelidae: Bruchinae), of an invasive weed, Leucaena leucocephala

Midori TUDA
Abstract An endophagous seed predator, Acanthoscelides macrophthalmus (Coleoptera: Chrysomelidae: Bruchinae), utilizes Neotropical Leucaena (Fabaceae: Mimosoideae). One of its hosts, Leucaena leucocephala, is a fast-growing nitrogen-fixing tree that serves as a multipurpose beneficial plant but eventually becomes an aggressive invader where it was introduced. Herein, we report A. macrophthalmus invasion of the Far East, South Asian tropics and subtropics (Japanese Pacific Islands, Taiwan, Southern China, Northern Thailand and Southern India). Of other field-collected mimosoid legumes, an introduced tree, Falcataria moluccana, in Taiwan was found to be used by the seed predator. Conversely, our published work review revealed that the seed predator had retained high host specificity to Leucaena species in its native and introduced regions. Acanthoscelides macrophthalmus was able to utilize aphagously postharvest mature seeds for oviposition and larval development, which is a trait of post-dispersal seed predators. We confirmed that A. macrophthalmus that was reared on L. leucocephala was able to utilize F. moluccana as well. Although the relatively high host specificity of the oligophagous beetle is suitable for controlling the weedy L. leucocephala, the potential host range expansion confirmed by this study must be cautioned. [source]

Polymorphic microsatellite markers in polyploid Lepidium draba L. ssp. draba (Brassicaceae) and cross-species amplification in closely related taxa

Abstract Heart-podded hoary cress, Lepidium draba L. ssp. draba (Brassicaceae) is a noxious invasive weed in the USA. At present, efficient biological control of this Eurasian native weed in the USA is hampered by lack of knowledge of its population genetic structure and colonization process. Here, we describe the development of 11 polymorphic microsatellite markers that also reveal the polyploidy of this weed. Successful cross-species amplification highlights the possibility of using these markers for genetic studies in other closely related species. [source]

The small-scale spatiotemporal pattern of the seedbank and vegetation of a highly invasive weed, Centaurea solstitialis: strength in numbers

OIKOS, Issue 3 2010
Christopher J. Lortie
The dynamics of invasive plant populations are intriguing and informative of the importance of population and community-level processes. A dominant approach to understanding and describing invasion has been the development of unique hypotheses to explain invasion. However, here we directly explore the relevance of the small-scale, spatiotemporal pattern in seedbanks and plants of the highly invasive weed, Centaurea solstitialis, to determine whether pattern can be used to contrast predictions associated with the simple ecological hypotheses of seed versus microsite limitations. At three invaded grasslands in California, highly invaded (> 20 adult plants present), invaded (< 10 adults), and uninvaded (no C. solstitialis plants) sites were selected. The spatial pattern of the seedbank was assessed using fine-scale, 2 cm diameter contiguous cores and geostatistical statistics, and the number of C. solstitialis seeds in the seedbank was recorded in addition to the total community seedbank density. Three of the four critical predictions associated with the seed limitation hypothesis were clearly supported as an explanation for the patterns of C. solstitialis invasion observed in the field. The density of C. solstitialis seeds decreased from high to low extents of invasion, there was no relationship between the community seedbank and C. solstitialis seeds, and the distances between C. solstitialis plants was inversely related to the density of C. solstitialis seeds. However, both the persistent and transient seedbanks of C. solstitialis were spatially aggregated with autocorrelation up to 12 cm2 which suggests that aggregation is a consistent attribute of this species in the seedbank regardless of extent of invasion. This basic pattern-based approach clearly detected an ecological signal of invasive seedbank dynamics and is thus a useful tool for subsequent studies of invasions in grasslands. [source]

Seasonal phenology of the gall-making fly Fergusonina sp. (Diptera: Fergusoninidae) and its implications for biological control of Melaleuca quinquenervia

John A Goolsby
Abstract A gall-making fly, Fergusonina sp., is under study as a potential biological control agent of Melaleuca quinquenervia (Cav.) S. T. Blake, an invasive weed in Florida, USA. The seasonal phenology of Fergusonina sp. and its host M. quinquenervia was studied over 2 years in northern New South Wales and south-eastern Queensland. Fergusonina sp. populations followed an annual cycle, with gall numbers peaking in August/September. Gall density was strongly correlated with leaf bud density and temperature, but not rainfall. Comparison of climates in Australia across the native range of Fergusonina sp. with the climate of Miami, Florida, predicts that climate should not be a limiting factor in its establishment. The fly/nematode complex of Fergusonina/Fergusobia sp. is compared with other gall-making agents used in biological control programs. Galls are formed from primordial leaf bud and reproductive structures of the plant and have many of the attributes of a moderately powerful metabolic sink. High gall densities could potentially suppress seed production and reduce the vigour of the tree, which would make this insect species an effective biological control agent of M. quinquenervia. [source]

Differential Responses of the Activities of Antioxidant Enzymes to Thermal Stresses between Two Invasive Eupatorium Species in China

Ping Lu
Abstract The effect of thermal stress on the antioxidant system was investigated in two invasive plants, Eupatorium adenophorum Spreng. and E. odoratum L. The former is sensitive to high temperature, whereas the latter is sensitive to low temperature. Our aim was to explore the relationship between the response of antioxidant enzymes and temperature in the two invasive weeds with different distribution patterns in China. Plants were transferred from glasshouse to growth chambers at a constant 25 C for 1 week to acclimatize to the environment. For the heat treatments, temperature was increased stepwise to 30, 35, 38 and finally to 42 C. For the cold treatments, temperature was decreased stepwise to 20, 15, 10 and finally to 5 C. Plants were kept in the growth chambers for 24 h at each temperature step. In E. adenophorum, the coordinated increase of the activities of antioxidant enzymes was effective in protecting the plant from the accumulation of active oxygen species (AOS) at low temperature, but the activities of catalase (CAT), guaiacol peroxidase (POD), ascorbate peroxidase (APX), glutathione reductase (GR), and monodehydroascorbate reductase (MDAR) were not accompanied by the increase of superoxide dismutase (SOD) during the heat treatments. As a result, the level of lipid peroxidation in E. adenophorum was higher under heat stress than under cold stress. In E. odoratum, however, the lesser degree of membrane damage, as indicated by low monodehydroascorbate content, and the coordinated increase of the oxygen. Detoxifying enzymes were observed in heat-treated plants, but the antioxidant enzymes were unable to operate in cold stress. This indicates that the plants have a higher capacity for scavenging oxygen radicals in heat stress than in cold stress. The different responses of antioxidant enzymes may be one of the possible mechanisms of the differences in temperature sensitivities of the two plant species. [source]

Capsule Treatments to Enhance Seedling Emergence of Gaura neomexicana ssp. coloradensis

L. M. Burgess
Abstract Management of riparian vegetation is difficult because these communities are frequently impacted by herbivores, invasive weeds, and altered hydrologic regimes. Multiple and intertwined factors affecting rare species recruitment are particularly difficult to identify. Gaura neomexicana ssp. coloradensis Munz (Gaura) is a short-lived perennial forb endemic to riparian areas in mixed-grass prairies of Wyoming, Nebraska, and Colorado, U.S.A. It became a federally listed threatened species in October 2000. Because the species is a recruitment-limited monocarpic perennial, we studied the effects of six capsule-collection dates, a 2-month cool-moist stratification, 24-hr leaching, and 24-hr imbibition on Gaura seedling emergence. Seedling emergence did not vary with collection date. Capsules collected from Gaura plants grown at the Bridger Plant Materials Center in Montana exhibited greater emergence than capsules harvested from endemic populations near Cheyenne, Wyoming, suggesting that maternal plant growing conditions impact dormancy. Because cool-moist stratification enhanced seedling emergence of Gaura and leaching did not, sufficient moisture during cool temperatures may be more critical than leaching of germination inhibitors as might occur with normal stream flows. Spring flooding may enhance Gaura recruitment by increasing the availability of riparian sites that are inundated during periods of cool temperatures. If so, hydrologic and climatic regimes must be considered in restoring the unique conditions needed for germination of this rare riparian endemic. [source]