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 Asian tiger mosquito ( Aedes albopictus ) is one of the most invasive disease vectors worldwide. The species is a competent vector of dengue, chikungunya, Zika viruses and other severe parasites and pathogens threatening human health. The capacity of this mosquito to colonize and establish in new areas (including temperate regions) is enhanced by its ability of producing diapausing eggs that survive relatively cold winters. The main drivers of population dynamics for this mosquito are water and air temperature and photoperiod. In this paper, we present a mechanistic model that predicts the potential distribution, abundance and activity of Asian tiger mosquito in Europe. The model includes a comprehensive description of: i) the individual life-history strategies, including diapause, ii) the influence of weather-driven individual physiological responses on population dynamics and iii) the density-dependent regulation of larval mortality rate. The model is calibrated using field data ...

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...

Assessing the geographic distribution and abundance of invasive species is critical for developing sound management and/or eradication policies. Ecological niche modelling approaches (ENMs) that make implicit assumptions about biology and mathematics are commonly used to predict the potential distribution of invasive species based on their recorded distribution. An alternative approach is physiologically based demographic modelling (PBDM), which explicitly incorporates the mathematics and the observed biology, including trophic interactions, to predict the temporal phenology and dynamics of a species across wide geographic areas. The invasive weed, yellow starthistle (YST) (Centaurea solstitialis), and its interactions with annual grasses and herbivorous biological control agents is used to demonstrate the utility of the PBDM approach for analysing complex invasive species problems. The PBDM predicts the distribution and relative abundance of YST accurately across the western USA, and ...

Climate change is expected to alter the geographic distribution and abundance of many species, to increase the invasion of new areas by exotic species and, in some cases, to lead to extinction of species. This chapter reviews some of the links between invasive insects and climate change. The effects of climate change on insect pest populations can be direct, through impacts on their physiology and behaviour, or indirect, through biotic interactions (i.e. bottom-up and top-down eff ects). Anthropogenic climate and global change is expected to be a major driver in the introduction, establishment, distribution, impact and changes in the efficacy of mitigation strategies for invasive species. To address these problems, we must be able to predict climate change impacts on species distribution and abundance. Commonly used ecological niche modelling approaches have implicit assumptions about the biology of the target species and attempt to characterize the ecological niche using aggregate wea...

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...

The polyphagous European grapevine moth Lobesia botrana (Den. & Schiff.) is the principal native pest of grape berries in the Palearctic region. It was found in Napa County, California, in 2009, and it has subsequently been recorded in an additional nine counties, despite an ongoing eradication program. A holistic physiologically-based demographic model for L. botrana linked to an extant mechanistic model of grapevine was run using observed daily weather data to simulate and map (via GRASS GIS ) the potential distribution of the moth in California and the continental U.S.A. The model predicts L. botrana can spread statewide with the highest populations expected in the hotter regions of southern California and the lower half of the Central Valley. In the U.S.A., areas of highest favorability include south Texas, and much of the southeast U.S.A. With climate warming, L. botrana abundance is expected to increase in northern California and in the agriculturally rich Central Valley ...