1. Acacia nilotica is a spinescent woody legume that has become highly invasive in several parts of the world, including Australia where it has been declared a weed of national significance. ...Understanding the likely potential distribution of this notorious plant under current and future climate scenarios will enable policy makers and land managers to prepare appropriate strategies to manage the invasion. 2. CLIMEX was used to synthesize available information from diverse sources to model the invasion potential of A. nilotica and gain insights into the climatic factors limiting its range expansion. The model identified areas at risk of further invasion so that early preventative or ameliorative measures could be undertaken in a timely manner. 3. The potential distribution of A. nilotica in Australia under current climatic conditions is vast, and far greater than the current distribution. 4. Global climate change is likely to increase markedly the potential distribution of A. nilotica in Australia, significantly increasing the area at risk of invasion. The factors of most importance are the expected increases in water-use efficiency of A. nilotica due to increased atmospheric CO2concentrations, allowing it to invade more xeric sites further inland, and increased temperatures, allowing it to complete its reproductive life cycle further southward (poleward). 5. Synthesis and applications. Simple paddock quarantine procedures may provide a means of limiting the range of A. nilotica within its potential distribution under current, as well as future, climate scenarios. The projected increased growth potential of A. nilotica throughout its current range suggests that if future management patterns result in seed pods lying unconsumed on the ground, heightened vigilance may be required to identify and eradicate new invasion foci arising from flood dispersal. The increased growth potential may also result in an alteration of the economic balance, in favour of harvesting A. nilotica for agroforestry or local bioenergy projects. A crucial component in containing this invasion will be raising public awareness of the invasion threat posed by A. nilotica, its identification and suitable control techniques.
Invasive species, biological control and climate change are driving demand for tools to estimate species' potential ranges in new environments. Flawed results from some tools are being used to inform ...policy and management in these fields. Independent validation of models is urgently needed so we compare the performance of the ubiquitous, logistic regression and the CLIMEX model in predicting recent range extensions of the livestock tick, Rhipicephalus (Boophilus) microplus, in Africa. Both models have been applied to the tick so new, independent data can be used to test their ability to model non-equilibrium distributions. Logistical regression described the spatial data well but failed to predict the range extensions. CLIMEX correctly predicted the extensions without fitting the non-equilibrium data accurately. Our results question the validity of using descriptive, statistical models to predict changes in species ranges with translocation and climate change. More test cases that include independent validation are needed.
A critical comment on M. J. Samways, R. Osborn, H. Hastings & V. Hattingh (1999) Global climate change and accuracy of prediction of species geographical ranges: establishment success of introduced ...ladybirds (Coccinellidae, Chilocorus spp.) worldwide. Journal of Biogeography, 26, 795-812.
Right-Sizing Stem-Rust Research Pardey, P. G.; Beddow, J. M.; Kriticos, D. J. ...
Science (American Association for the Advancement of Science),
04/2013, Letnik:
340, Številka:
6129
Journal Article
Recenzirano
Is increased support needed for wheat disease research to avert crop losses from current and future strains?
Stem rust caused by
Puccinia graminis
f. sp.
tritici
is a potentially devastating fungal ...disease that can kill wheat plants and small grain cereals but more typically reduces foliage, root growth, and grain yields e.g., (
1
,
2
). After years of success in keeping the disease at bay, new virulent races (collectively referred to as “Ug99”) have emerged, with the potential to infect much of the world's wheat (
3
). Despite, or because of, the success of past research, these programs saw an eventual rundown in support (
4
). We estimate global wheat losses over the past 50 years absent investments in research to limit impacts of stem rust and discuss how this can inform decisions about “right-sizing” research investments.
Most ecological risk assessments for global change are restricted to the effects of trends in climate or atmospheric carbon dioxide. In order to move beyond investigation of the effects of climate ...alone, the climextrade mark sign model was extended to investigate the effects of species interactions, in the same or different trophic levels, along environmental gradients on a geographical scale. Specific needs that were revealed during the investigations include: better treatment of the effects of temporal and spatial climatic variation; elucidation of the nature of boundaries of species ranges; data to quantify the role of species traits in interspecies interactions; integrated observational, experimental, and modelling studies on mechanisms of species interactions along environmental gradients; and high-resolution global environmental datasets. Greater acknowledgement of the shared limitations of simplified models and experimental studies is also needed. Above all, use of the scientific method to understand representative species ranges is essential. This requires the use of mechanistic approaches capable of progressive enhancement.
The paucity of empirical data on processes in species life cycles demands tools to extract insight from field observations. Such insights help inform policy on invasive species and on impacts of ...climate change at regional and local scales. We used the CLIMEX model to infer the response of the red imported fire ant, Solenopsis invicta Buren (Hymenoptera: Formicidae), to temperature and moisture from its range in the United States. We tested hypotheses on the mechanisms that limit the distribution of the ant and estimated the potential global area at risk from invasion. The ant can spread further in the United States, including north along the west coast, where patterns of infestation will differ from those in the east. We analyzed the risk of colonization in Australia and New Zealand, where the ant was recently discovered. The patterns of infestation of the ant in Oceania will differ from those in the eastern United States, with slower growth and less winter mortality. This study adds to earlier temperature-based models by incorporating a moisture response; by replacing arbitrary categories of colony size to predict overwintering success with a site-specific model based on the balance between annual growth and survival; and by comparing different hypotheses on low temperature-related mechanisms that limit the geographical distribution. It shows how the response of a species to climate can be synthesized from field observations to provide useful insights into its population dynamics. Such analyses provide a basis for making decisions on regional management of invasive species and an informative context for local studies.
The Bemisia tabaci species complex is one of the most important pests of open field and protected cropping globally. Within this complex, one species (Middle East Asia Minor 1, B. tabaci MEAM1, ...formerly biotype B) has been especially problematic, invading widely and spreading a large variety of plant pathogens, and developing broad spectrum pesticide resistance. Here, we fit a CLIMEX model to the distribution records of B. tabaci MEAM1, using experimental observations to calibrate its temperature responses. In fitting the model, we consider the effects of irrigation and glasshouses in extending its potential range. The validated niche model estimates its potential distribution as being considerably broader than its present known distribution, especially in the Americas, Africa and Asia. The potential distribution of the fitted model encompasses the known distribution of B. tabaci sensu lato, highlighting the magnitude of the threat posed globally by this invasive pest species complex and the viruses it vectors to open field and protected agriculture.
The term ‘global change’ is used to encompass all of the significant drivers of environmental change as experienced by hosts, parasites and parasite managers. The term includes changes in climate and ...climate variability, atmospheric composition, land use and land cover including deforestation and urbanisation, bio-geochemistry, globalisation of trade and transport, the spread of alien species, human health and technology. A subset of land use issues relates to the management of protective technologies in relation to residues in food and the environment and the emergence of resistance. Another is the question of changing biodiversity of both parasites and their associated natural enemies, and the effects on the host–parasite relationship and on parasite management. A framework for studying impacts of global change is proposed and illustrated with field data, and CLIMEX and simulation modelling of the cattle tick Boophilus microplus in Australia. Parasitology suffers from the perception that the key impacts of global change will be driven by changes at lower trophic levels, with parasitic interactions being treated as secondary effects. This is incorrect because the environment mediates host–parasite interactions as much as it affects parasites directly. Parasitologists need to strive for holistic solutions to the management of animal and human health, within a wider context of overall management of those systems, if they are to make a meaningful contribution to global efforts aimed at coping with global change.
Process-based population models need sound and comprehensive data on an animal's response to climatic factors if they are to function reliably under a wide range of climatic conditions. To this end, ...different aged egg masses of the livestock tick,
Rhipicephalus (Boophilus) microplus, were either desiccated in atmospheres with saturation deficits of 5, 10, 15 or 20
mmHg at 20 or 26
°C, or chilled at temperatures of 5, 10 or 14
°C with a saturation deficit of 1
mmHg for varying periods. The survival rate of the eggs through to hatching was related to the initial age of the eggs, the severity of the treatments and the duration of exposure. We established a relationship between desiccation and weight loss of eggs and, secondarily between weight loss and mortality. Mortality increased with weight loss until it reached 100% when the weight loss was about 35%. Low temperatures were increasingly detrimental to eggs as they reduced from 14 to 5
°C. Freshly laid eggs were more susceptible to both low temperatures and desiccation than were older eggs. Larvae emerging from eggs that were stressed by either cold or desiccation lived for a shorter time under optimal conditions than did larvae from eggs incubated under optimal conditions. Larvae from eggs with the same hatching rate had the same viability, whether the stress was induced by desiccation or low temperatures. Models were developed to describe the dynamics of weight loss of eggs with desiccation, the accumulation of cold stress of the eggs, and their effects on egg survival and larval viability. These data provide a sound basis for the development of predictive models for use under field conditions, although the response of different aged eggs to low temperatures was too variable to allow us to develop an accurate model to describe that relationship. Field models will also need to take diurnal temperature fluctuations into account.
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