Noboru Ota

The potential distribution of invading Helicoverpa armigera in North America: Is it just a matter of time?

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

The potential global distribution of Chilo partellus, including consideration of irrigation and cropping patterns

78 billion p.a., with US

Downscaling Pest Risk Analyses: Identifying Current and Future Potentially Suitable Habitats for Parthenium hysterophorus with Particular Reference to Europe and North Africa

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.

Extending the suite of bioclim variables: a proposed registry system and case study using principal components analysis

Chilo partellus is a major crop pest in Asia and Africa, and has recently spread to the Mediterranean region. Knowledge of its potential distribution can inform biosecurity policies aimed at limiting its further spread and efforts to reduce its impact in areas that are already invaded. Three models of the potential distribution of this insect have been published, each with significant shortcomings. We re-parameterized an existing CLIMEX model to address some parameter inconsistencies and to improve the fit to the known distribution of C. partellus. The resulting model fits the known distribution better than previous models, highlights additional risks in equatorial regions and reduces modelled risks in wet and extremely dry regions. We bring new insights into the role of irrigation in the potential spread of this invasive insect and compare its potential distribution with the present known distribution of its hosts. We also distinguish regions that are suitable for supporting persistent populations from those that may be at risk from ephemeral populations during favourable seasons. We present one of the first demonstrations of a new capability in CLIMEX to automatically estimate parameter sensitivity and model uncertainty. Our CLIMEX model highlights the substantial invasion risk posed by C. partellus to cropping regions in the Americas, Australia, China, Europe, New Zealand and West Africa. Its broad host range and reported impacts suggest that it should be a pest of significant concern to biosecurity agencies in these presently uninvaded regions.

The potential distribution of cassava mealybug (Phenacoccus manihoti), a threat to food security for the poor

Pest Risk Assessments (PRAs) routinely employ climatic niche models to identify endangered areas. Typically, these models consider only climatic factors, ignoring the ‘Swiss Cheese’ nature of species ranges due to the interplay of climatic and habitat factors. As part of a PRA conducted for the European and Mediterranean Plant Protection Organization, we developed a climatic niche model for Parthenium hysterophorus, explicitly including the effects of irrigation where it was known to be practiced. We then downscaled the climatic risk model using two different methods to identify the suitable habitat types: expert opinion (following the EPPO PRA guidelines) and inferred from the global spatial distribution. The PRA revealed a substantial risk to the EPPO region and Central and Western Africa, highlighting the desirability of avoiding an invasion by P. hysterophorus. We also consider the effects of climate change on the modelled risks. The climate change scenario indicated the risk of substantial further spread of P. hysterophorus in temperate northern hemisphere regions (North America, Europe and the northern Middle East), and also high elevation equatorial regions (Western Brazil, Central Africa, and South East Asia) if minimum temperatures increase substantially. Downscaling the climate model using habitat factors resulted in substantial (approximately 22–53%) reductions in the areas estimated to be endangered. Applying expert assessments as to suitable habitat classes resulted in the greatest reduction in the estimated endangered area, whereas inferring suitable habitats factors from distribution data identified more land use classes and a larger endangered area. Despite some scaling issues with using a globally conformal Land Use Systems dataset, the inferential downscaling method shows promise as a routine addition to the PRA toolkit, as either a direct model component, or simply as a means of better informing an expert assessment of the suitable habitat types.

Erratum: The Potential Distribution of Invading Helicoverpa armigera in North America: Is It Just a Matter of Time? (PLoS ONE (2015) 10:7 (e0133224) DOI:10.1371/journal.pone.0133224)

Summary The so-called BIOCLIM variables have played a central role in the advancement of ecologicalmodellingmethods for correlative species distribution modelling. We propose to establish a register of the BIOCLIMvariables, allowing for the extension of the suite of described, readily available covariate data tosupport bioclimatic modelling. The registry will provide a simple means for researchers to add usefuldata sets in a transparent, documented manner. As a case study, we introduce and describe the set offivemost significant principal components of the first 35 BIOCLIM variables (Bio01 to Bio35) and proposethey be assigned as Bio36 to Bio40.Together, these five PCA variables capture more than 90%of thevariability in the full suite of 35 BIOCLIM variables. The PCA variables may provide a means to explore the climaticlimits of poorly known species, with a reduced risk of overfitting the models. The BIOCLIM variable registry should facilitate the expansion of the suite of variables commonly used in species distribution modelling.

Supporting global biodiversity assessment through high-resolution macroecological modelling: Methodological underpinnings of the BILBI framework

The cassava mealybug is a clear and present threat to the food security and livelihoods of some of the worlds most impoverished citizens. Niche models, such as CLIMEX, are useful tools to indicate where and when such threats may extend, and can assist with planning for biosecurity and the management of pest invasions. They can also contribute to bioeconomic analyses that underpin the allocation of resources to alleviate poverty. Because species can invade and establish in areas with climates that are different from those that are found in their native range, it is essential to define robust range-limiting mechanisms in niche models. To avoid spurious results when applied to novel climates, it is necessary to employ cross-validation techniques spanning different knowledge domains (e.g., distribution data, experimental results, phenological observations). We build upon and update a CLIMEX niche model by Parsa et al. (PloS ONE 7: e47675), correcting inconsistent parameters and re-fitting it based on a careful examination of geographical distribution data and relevant literature. Further, we consider the role of irrigation, the known distribution of cassava production and a targeted review of satellite imagery to refine, validate and interpret our model and results. In so doing, we bring new insights into the potential spread of this invasive insect, enabling us to identify potential bio-security threats and biological control opportunities. The fit of the revised model is improved, particularly in relation to the wet and dry limits to establishment, and the parameter values are biologically plausible and accord with published scientific literature.

Considering biology when inferring range-limiting stress mechanisms for agricultural pests: a case study of the beet armyworm

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

CliMond: global high‐resolution historical and future scenario climate surfaces for bioclimatic modelling

78 billion p.a., with US

Modelling horses for novel climate courses: insights from projecting potential distributions of native and alien Australian acacias with correlative and mechanistic models

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 preemptive 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, PLOS ONE | DOI:10.1371/journal.pone.0119618 March 18, 2015 1 / 24 OPEN ACCESS Citation: Kriticos DJ, Ota N, Hutchison WD, Beddow J, Walsh T, Tay WT, et al. (2015) The Potential Distribution of Invading Helicoverpa armigera in North America: Is It Just a Matter of Time?. PLoS ONE 10(3): e0119618. doi:10.1371/journal.pone.0119618 Academic Editor: Erjun Ling, Institute of Plant Physiology and Ecology, CHINA Received: October 20, 2014 Accepted: January 14, 2015 Published: March 18, 2015 Copyright: This is an open access article, free of all copyright, and may be freely reproduced, distributed, transmitted, modified, built upon, or otherwise used by anyone for any lawful purpose. The work is made available under the Creative Commons CC0 public domain dedication. Data Availability Statement: All relevant data are within the paper and its Supporting Information files. Funding: DJK and MPZ were partly financially supported by Cotton Inc., but otherwise were supported by their employers, the Commonwealth Scientific and Industrial Research Organisation and The University of Queensland respectively with nonspecific funding. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. Competing Interests: The authors have declared that no competing interests exist. emphasizing the value of preparatory communication with agricultural producers in areas suitable for invasion by H. armigera.