Climate Change and the Potential Distribution of an Invasive Shrub, Lantana camara L

The threat posed by invasive species, in particular weeds, to biodiversity may be exacerbated by climate change. Lantana camara L. (lantana) is a woody shrub that is highly invasive in many countries of the world. It has a profound economic and environmental impact worldwide, including Australia. Knowledge of the likely potential distribution of this invasive species under current and future climate will be useful in planning better strategies to manage the invasion. A process-oriented niche model of L. camara was developed using CLIMEX to estimate its potential distribution under current and future climate scenarios. The model was calibrated using data from several knowledge domains, including phenological observations and geographic distribution records. The potential distribution of lantana under historical climate exceeded the current distribution in some areas of the world, notably Africa and Asia. Under future scenarios, the climatically suitable areas for L. camara globally were projected to contract. However, some areas were identified in North Africa, Europe and Australia that may become climatically suitable under future climates. In South Africa and China, its potential distribution could expand further inland. These results can inform strategic planning by biosecurity agencies, identifying areas to target for eradication or containment. Distribution maps of risk of potential invasion can be useful tools in public awareness campaigns, especially in countries that have been identified as becoming climatically suitable for L. camara under the future climate scenarios

Biological, environmental and socioeconomic threats to citrus lime production

Limes as a fruit crop are of great economic importance, key to Asian and South American cuisines and cultivated in nearlyall tropical and subtropical regions of the world. Demand for limes is increasing, driven by World Health Organizationrecommendations. Pests and pathogens have significantly reduced global productivity, while changes in agronomictechniques aim to alleviate this stress. We present here a holistic examination of the major biotic (pests and pathogens) andabiotic (environment and socioeconomic) factors that presently limit global production of lime. The major producers oflimes are India, China and Mexico, while loss of lime production in the United States from 2006 has led many countries inthe Western Hemisphere (Mexico, Costa Rica and Brazil) to export primarily to the USA. The most widespread inver-tebrate pests of lime areToxoptera citricidaandScirtothrips citri. Another insect,Diaphorina citri, vectors both Huan-glongbing (HLB) and Witches Broom of Lime, which are particularly destructive diseases. Developing agronomictechniques focus on production of resistant and pathogen-free planting materials and control of insect vectors. HLB infectscitrus in nearly all growing regions, and has been particularly devastating in Asian citrus. Meanwhile,Citrus tristeza virushas infected over 100 million citrus trees, mainly in the Americas and Mediterranean. Currently, Witches Broom Disease ofLime is localised to the Middle East, but recently it has been detected in South America. The range of its vectors (D. citriandHishimonus phycitis) further raises concerns about the potential spread of this disease. Abiotic threats to limeproduction are also a significant concern; key areas of lime production such as Mexico, India and the Middle East sufferfrom increasing water stress and high soil salinity, which combined with invasive pests and pathogens, may eliminate limeproduction in these areas. To ensure future security in lime production, policy makers, researchers and growers will need toexamine the potential of more resistant lime cultivars and establish novel areas of cultivation

Diversity of saprobic microfungi

The data needed to derive an accurate estimate of saprobic microfungi are insufficient, incomplete and contradictory. We therefore address issues that will ultimately reveal whether there are 1.5 million global fungal species, which is the generally accepted working estimate. Our data indicates that large numbers of fungi occur on host families, such as Musaceae, host genera such as Nothofagus and individual host species such as Eucalyptus globulus, and that fungi may be specific or recurrent on different plant groups. Recent studies have shown that fungal numbers on hosts may be larger than originally thought as saprobes are organ-specific/-recurrent and changes in fungal communities occur as substrata decays. Other issues, such as the impact of geography, of methodology and of taxonomy are also addressed. There is evidence that fungi on the same host at different locations also differs; site-specific factors and geographic distance may be more important than host/substrate in shaping fungal assemblages. Methodology impacts on estimates of species diversity with many more taxa observed using indirect isolation protocols as compared to direct isolations from leaves. Our understanding of fungal species numbers in speciose genera is important. In some fungal groups accepted species have been reduced to a few species, while in other groups many cryptic species are being uncovered. While we make a number of generalisations from the studies reported here, this review also highlights some of the limitations mycologists currently have to contend with. A large body of knowledge exists for certain groups of microfungi or for microfungi occurring on certain substrata/hosts. However, it is likely that we are drawing conclusions from data that are somewhat biased toward fungi and host/substrata that are of interest to human endeavours. The discrepancy between the numbers of fungi described from only one economically important genus, Eucalyptus, and all the other members of the Myrtaceae is but one example of this bias. By incorporating the large body of work that is already available and adding appropriate complementary studies, we can accelerate our understanding of microfungal diversity and this will eventually lead us to a realistic estimate of global fungal species numbers.