Summary1. Gridded climatologies have become an indispensable component of bioclimatic modelling, with a range of applications spanning conservation and pest management. Such globally conformal data sets of historical and future scenario climate surfaces are required to model species potential ranges under current and future climate scenarios. 2. We developed a set of interpolated climate surfaces at 10¢ and 30¢ resolution for global land areas excluding Antarctica. Input data for the baseline climatology were gathered from the WorldClim and CRU CL1AE0 and CL2AE0 data sets. A set of future climate scenarios were generated at 10¢ resolution. For each of the historical and future scenario data sets, the full set of 35 Bioclim variables was generated. Climate variables (including relative humidity at 0900 and 1500 hours) were also generated in CLIMEX format. The Ko¨ppen-Geiger climate classification scheme was applied to the 10¢ hybrid climatology as a tool for visualizing climatic patterns and as an aid for specifying absence or background data for correlative modelling applications. 3. We tested the data set using a correlative model (MaxEnt) addressing conservation biology concerns for a rare Australian shrub, and a mechanistic niche model (CLIMEX) to map climate suitability for two invasive species. In all cases, the underlying climatology appeared to behave in a robust manner. 4. This global climate data set has the advantage over the WorldClim data set of including humidity data and an additional 16 Bioclim variables. Compared with the CRU CL2AE0 data set, the hybrid 10¢ data set includes improved precipitation estimates as well as projected climate for two global climate models running relevant greenhouse gas emission scenarios. 5. For many bioclimatic modelling purposes, there is an operational attraction to having a globally conformal historical climatology and future climate scenarios for the assessments of potential climate change impacts. Our data set is known as 'CliMond' and is available for free download from http://www.climond.org.

Summary1. 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 CO 2 concentrations, allowing it to invade more xeric sites further inland, and increased temperatures, allowing it to complete its reproductive life cycle further southward (poleward). 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.

The oriental fruit fly, Bactrocera dorsalis (Hendel), is a major pest throughout South East Asia and in a number of Pacific Islands. As a result of their widespread distribution, pest status, invasive ability and potential impact on market access, B. dorsalis and many other fruit fly species are considered major threats to many countries. CLIMEX was used to model the potential global distribution of B. dorsalis under current and future climate scenarios. Under current climatic conditions, its projected potential distribution includes much of the tropics and subtropics and extends into warm temperate areas such as southern Mediterranean Europe. The model projects optimal climatic conditions for B. dorsalis in the south-eastern USA, where the principle range-limiting factor is likely to be cold stress. As a result of climate change, the potential global range for B. dorsalis is projected to extend further polewards as cold stress boundaries recede. However, the potential range contracts in areas where precipitation is projected to decrease substantially. The significant increases in the potential distribution of B. dorsalis projected under the climate change scenarios suggest that the World Trade Organization should allow biosecurity authorities to consider the effects of climate change when undertaking pest risk assessments. One of the most significant areas of uncertainty in climate change concerns the greenhouse gas emissions scenarios. Results are provided that span the range of standard Intergovernmental Panel on Climate Change scenarios. The impact on the projected distribution of B. dorsalis is striking, but affects the relative abundance of the fly within the total suitable range more than the total area of climatically suitable habitat.

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Aim Investigate the relative abilities of different bioclimatic models and data sets to project species ranges in novel environments utilizing the natural experiment in biogeography provided by Australian Acacia species.Location Australia, South Africa. MethodsWe built bioclimatic models for Acacia cyclops and Acacia pycnantha using two discriminatory correlative models (MaxEnt and Boosted Regression Trees) and a mechanistic niche model (CLIMEX). We fitted models using two training data sets: native-range data only ('restricted') and all available global data excluding South Africa ('full'). We compared the ability of these techniques to project suitable climate for independent records of the species in South Africa. In addition, we assessed the global potential distributions of the species to projected climate change.Results All model projections assessed against their training data, the South African data and globally were statistically significant. In South Africa and globally, the additional information contained in the full data set generally improved model sensitivity, but at the expense of increased modelled prevalence, particularly in extrapolation areas for the correlative models. All models projected some climatically suitable areas in South Africa not currently occupied by the species. At the global scale, widespread and biologically unrealistic projections by the correlative models were explained by open-ended response curves, a problem which was not always addressed by broader background climate space or by the extra information in the full data set. In contrast, the global projections for CLIMEX were more conservative. Projections into 2070 indicated a polewards shift in climate suitability and a decrease in model interpolation area.Main conclusions Our results highlight the importance of carefully interpreting model projections in novel climates, particularly for correlative models. Much work is required to ensure bioclimatic models performed in a robust and ecologically plausible manner in novel climates. We explore reasons for variations between models and suggest methods and techniques for future improvements.

Breeding new crop varieties with resistance to the biotic stresses that undermine crop yields is tantamount to increasing the amount and quality of biological capital in agriculture. However, the success of genes that confer resistance to pests induces a co-evolutionary response that depreciates the biological capital embodied in the crop, as pests evolve the capacity to overcome the crop's new defences. Thus, simply maintaining this biological capital, and the beneficial production and economic outcomes it bestows, requires continual reinvestment in new crop defences. Here we use observed and modelled data on stripe rust occurrence to gauge changes in the geographic spread of the disease over recent decades. We document a significant increase in the spread of stripe rust since 1960, with 88% of the world's wheat production now susceptible to infection. Using a probabilistic Monte Carlo simulation model we estimate that 5.47 million tonnes of wheat are lost to the pathogen each year, equivalent to a loss of US$979 million per year. Comparing the cost of developing stripe-rust-resistant varieties of wheat with the cost of stripe-rust-induced yield losses, we estimate that a sustained annual research investment of at least US$32 million into stripe rust resistance is economically justified.

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Helicoverpa armigera has recently invaded South and Central America, and appears to be spreading rapidly. We update a previously developed potential distribution model to highlight the global invasion threat, with emphasis on the risks to the United States. The continued range expansion of H. armigera in Central America is likely to change the invasion threat it poses to North America qualitatively, making natural dispersal from either the Caribbean islands or Mexico feasible. To characterise the threat posed by H. armigera, we collated the value of the major host crops in the United States growing within its modelled potential range, including that area where it could expand its range during favourable seasons. We found that the annual value of crops that would be exposed to H. armigera totalled approximately US$78 billion p.a., with US$843 million p.a. worth growing in climates that are optimal for the pest. Elsewhere, H. armigera has developed broad-spectrum pesticide resistance; meaning that if it invades the United States, protecting these crops from significant production impacts could be challenging. It may be cost-effective to undertake pre-emptive biosecurity activities such as slowing the spread of H. armigera throughout the Americas, improving the system for detecting H. armigera, and methods for rapid identification, especially distinguishing between H. armigera, H. zea and potential H. armigera x H. zea hybrids. Developing biological control programs, especially using inundative techniques with entomopathogens and parasitoids could slow the spread of H. armigera, and reduce selective pressure for pesticide resistance. The rapid spread of H. armigera through South America into Central America suggests that its spread into North America is a matter of time. The likely natural dispersal routes preclude aggressive incursion responses, emphasizing the value of preparatory communication with agricultural producers in areas suitable for invasion by H. armigera.