the GlobalChangeBiology blog

The capacity to assess invasion risk from potential crop pests before invasion of new regions globally would be invaluable, but this requires the ability to predict accurately their potential geographic range and relative abundance in novel areas. This may be unachievable using de facto standard correlative methods as shown for the South American tomato pinworm Tuta absoluta , a serious insect pest of tomato native to South America. Its global invasive potential was not identified until after rapid invasion of Europe, followed by Africa and parts of Asia where it has become a major food security problem on solanaceous crops. Early prospective assessment of its potential range is possible using physiologically based demographic modeling that would have identified knowledge gaps in T. absoluta biology at low temperatures. Physiologically based demographic models (PBDMs) realistically capture the weather-driven biology in a mechanistic way allowing evaluation of invasive risk in novel ar...

The grapevine moth Lobesia botrana (Den. & Schiff.) (Lepidoptera: Tortricidae) is the principal native pest of grape in the Palearctic region. In the present study, we assessed prospectively the relative abundance of the moth in Europe and the Mediterranean Basin using linked physiologically‐based demographic models for grape and L. botrana . The model includes the effects of temperature, day‐length and fruit stage on moth development rates, survival and fecundity. Daily weather data for 1980–2010 were used to simulate the dynamics of grapevine and L. botrana in 4506 lattice cells across the region. Average grape yield and pupae per vine were used as metrics of favourability. The results were mapped using the grass Geographic Information System ( http://grass.osgeo.org ). The model predicts a wide distribution for L. botrana with highest populations in warmer regions in a wide band along latitude 40°N. The effects of climate warming on grapevine and L. botrana were explored usi...

The polyphagous Asian vinegar fly Drosophila suzukii (spotted wing Drosophila) is a native of Eastern and Southeastern Asia. It emerged as an important invasive insect pest of berries and stone fruits in the Americas and Europe beginning in 2008. Species distribution models are commonly used for analyzing the extant and potential range expansion of invasive species. Previous modeling efforts for D. suzukii include a degree-day model, a MaxEnt ecological niche model, a demographic model incorporating the effects of temperature, and a preliminary mechanistic physiologically-based demographic model (PBDM). In the present analysis, we refine the PBDM for D. suzukii based on biological data reported in the literature. The PBDM is used to assess the effects of temperature and relative humidity from a recently published global climate dataset (AgMERRA) on the prospective geographic distribution and relative abundance of the pest in the USA and Mexico, and in Europe and the Mediterranean Ba...

The distribution and abundance of species that cause economic loss (i.e., pests) in crops, forests or livestock depends on many biotic and abiotic factors that are thought difficult to separate and quantify on geographical and temporal scales. However, the weather-driven biology and dynamics of such species and of relevant interacting species in their food chain or web can be captured via mechanistic physiologically based demographic models (PBDMs) that can be implemented in the context of a geographic information system (GIS) to project their potential geographic distribution and relative abundance given observed or climate change scenarios of weather. PBDMs may include bottom-up effects of the host on pest dynamics and, if appropriate, the top-down action of natural enemies. When driven by weather, PBDMs predict the phenology, age structure and abundance dynamics at one or many locations enabling projecting the distribution of the interacting species across wide geographic areas. PBD...

The Asian tiger mosquito ( Ae. albopictus ) is indigenous to the oriental region, but is now widespread throughout the world. It is an aggressive mosquito, which causes nuisance and is well known vector of important human disease. It is one of the world’s most invasive species and is now invading Europe by both natural means and human assisted dispersal. Currently, there is no consensus on the limits of its potential geographic distribution in Europe. For this reason, studying the role that environmental driving variables, mainly temperature, play in determining the spatial variation of the potential population abundance of the mosquito should be considered a high priority. To assess the risk posed by Ae. albopictus to Europe, a lattice model based on the temperature-dependent physiologically based demographic modelling approach has been developed and is being tested against field observations. The area of potential distribution of this insect is simulated as driven by current climate...

A comment appeared in Proceedings B reviews a study by Papadopoulos, Plant, and Carey (2013; "From trickle to flood: the large-scale, cryptic invasion of California by tropical fruit flies." Proc. R. Soc. B: Biol. Sci. 280: http://dx.doi.org/10.1098/rspb.2013.1466 ) and suggests an alternative approach that addresses the biology of invasive species. In summary, inference of establishment of fruit flies based on recurrence data as performed by Papadopoulos et al. (2013) is neither explanatory nor provides confirmation of establishment in California. By contrast, physiologically based demographic models for medfly and olive fly accurately predict the potential distribution of the two fruit flies in California and elsewhere, and provide explanation for species phenology and dynamics that is critical for risk assessment and policy development for these and other invasive species under current climate and climate change scenarios. Gutierrez A.P., Ponti L., Gilioli G., 2014. Comm...

Using published bi- and tri-trophic physiologically-based demographic system models having similar sub components, the geographic distributions and relative abundance (a measure of invasiveness) of six invasive herbivorous insect species is assessed prospectively across the United States and Mexico. The models used are mechanistic descriptions of the weather-driven biology of the species. The plant hosts and insect species included in the study are: (1) cotton/pink bollworm, (2) a fruit tree host/Mediterranean fruit fly, (3) olive/olive fly, (4) a perennial host/light brown apple moth; (5) grapevine/glassy-winged sharpshooter and its two egg parasitoids, (6) grapevine/European grapevine moth. All of these species are currently or have been targets for eradication. The goal of the analyses is to predict and explain prospectively the disparate distributions of the six species as a basis for examining eradication/containment efforts against them. The eradication of the new world screwworm...

Olive is of major eco-social importance for the desertification-prone Mediterranean Basin, a climate change and biodiversity hotspot of global relevance where remarkable climate change is expected over the next few decades with unknown ecosystem impacts. However, climate impact assessments have long been constrained by a narrow methodological basis (ecological niche models, ENMs) that is correlative and hence largely omits key impact drivers such as trophic interactions and the effect of water availability. To bridge this gap, mechanistic approaches such as physiologically-based weather-driven demographic models (PBDMs) may be used as they embed by design both the biology of trophic interactions and a mechanistic representation of soil water balance. Here we report progress towards assessing climate effects on olive culture across the Mediterranean region using mechanistic PBDMs that project regionally the multitrophic population dynamics of olive and olive fly as affected by daily wea...

In a chapter to appear in the Handbook of Climate Change and Agroecosystems , four approaches used to estimate the potential distribution of native and invasive species in agricultural, natural and medical/veterinary vector/disease systems in the face of climate change are reviewed: (1) time-series observations to document biological responses to changes in climatic variables; (2) remote sensing analysis of data; (3) climate envelope approaches (statistically-based ecological niche models and physiologically-based ecological niche models); (4) physiologically based demographic models. The bases and relative merits of the approaches are discussed. The chapter emphasizes physiologically based demographic models that may be used at the individual, population and regional scales. Such models easily include multiple trophic levels as demonstrated for the olive/olive scale system. The olive/olive-fly system embedded in a geographic information system (GIS) is used to illustrate the utility o...

The highly polyphagous light brown apple moth (LBAM) ( Epiphyas postvittana (Walk.): Tortricidae) is indigenous to Australia and was first found in California in 2006. It is currently found in 15 coastal counties in California, but nowhere has it reached outbreak status. The USDA projects the geographic range of LBAM will include much of Arizona and California and the southern half of the U.S., which together with economic estimates of potential crop losses have been used as the rationale for an eradication program in California. We report a temperature-driven demographic model to predict the likely distribution and relative abundance of LBAM using the detailed biology reported by W. Danthanarayana and colleagues, and climate data from 151 locations in California and Arizona for the period 1995 to 2006. The predictions of our model suggest that the near coastal regions of California are most favorable for LBAM, the northern Central Valley of California being less favorable, and the de...