Archive for the ‘physiologically based models’ Category

Impact of the rosette weevil on yellow starthistle

March 13, 2017 Leave a comment

Yellow starthistle (Centaurea solstitialis L.) (YST) is an invasive weed native to the Mediterranean region with a geographical centre of diversity in Turkey. It is widely established in Chile, Australia, and western North America. It arrived in California as a contaminant in alfalfa seed in 1859 and, by 2002, had infested more than 7.7 million hectares in the U.S.A. Biological control of YST using capitula feeding weevils, picture wing flies and a foliar rust pathogen has been ongoing in the western U.S.A. for more than three decades with limited success. Modelling and field research suggest natural enemies that kill whole plants and/or reduce seed production of survivors are good candidates for successful biological control. A candidate species with some of these attributes is the rosette weevil Ceratapion basicorne (Illiger). In the present study, a model of the rosette weevil is added to an extant system model of YST and its capitula feeding natural enemies and, in a GIS context, is used to assess YST control in the Palearctic region and the weevil’s potential impact on YST in western U.S.A. The results obtained suggest densities of mature YST plants in western U.S.A. would be reduced by 70–80% in many areas.

Gutierrez A.P., Ponti L., Cristofaro M., Smith L., Pitcairn M.J., 2016. Assessing the biological control of yellow starthistle (Centaurea solstitialis L.): prospective analysis of the impact of the rosette weevil (Ceratapion basicorne (Illiger)). Agricultural and Forest Entomology,

The rosette weevil Ceratapion basicorne.

Earth observation: bridging the gap to crop-pest systems

November 16, 2016 Leave a comment

The workshop “When Space Meets Agriculture” aimed at promoting a better understanding of the significance and potential of Europe’s space systems (EGNOS/Galileo and Copernicus) for the agricultural sector. While introducing Rural Development Programmes of selected regions and exploring opportunities to set synergies for the development of space applications for the agriculture sector, it will present the main strands of the European Agriculture Policy and more generally link the space community to the agriculture community. Our contribution identified recent and prospective holistic analyses of climate change effects on crop-pest systems in the Mediterranean Basin. The approach used in the analyses involves using physiologically based demographic modeling (PBDM) of crop-pest-natural enemy interactions in the context of a geographic information system (GIS). A major goal is to link the PBDM/GIS technology with increasingly available biophysical datasets from global modeling and satellite observations, and use them to bridge the gap between bottom-up (primarily physiological and population dynamics) and top-down (climatological) GIS approaches for assessing on ground ecosystem level problems, such as agricultural pests.

Ponti L., Gutierrez A.P., Iannetta M., 2016. Climate change and crop-pest dynamics in the Mediterranean Basin. When Space Meets Agriculture: Fostering Interregional collaborations, investments and definition of user requirements. Workshop organized by NEREUS, the Network of European Regions Using Space Technologies, Matera, Italy, 14‐15 November 2016. | Presentation freely available online

Conceptual diagram representing how physiologically-based demographic models bridge the gap between bottom-up (primarily physiological and population dynamics) and top-down (climatological, remote sensing, and ecological niche modeling) GIS approaches for assessing on-ground ecosystem-level problems such as agricultural pests (see Rocchini et al. 2015).

Crop-pest dynamics in the Mediterranean Basin

September 30, 2016 Leave a comment

Climate change will make assessing and managing crop-pest systems in the Mediterranean Basin more difficult than elsewhere on the globe. The Basin is in many ways a hot spot of global change, as higher than average projected climate change threatens an extremely rich and intertwined biological and cultural diversity, and increases its vulnerability to biological invasions. As a consequence, pest problems in this hot spot will require a holistic approach to deconstruct the elusive complex interactions that are the underpinning basis for sound decision making at the field level. Building on 30+ years of multidisciplinary progress inspired by pioneering work at University of California, the ENEA GlobalChangeBiology project in collaboration with CASAS Global is developing an interdisciplinary tool to mechanistically describe (i.e., model), analyze and manage agro-ecological problems based on the unifying paradigm that all organisms including humans acquire and allocate resources by analogous processes – the paradigm of ecological analogies that is holistic by design. Recent analyses using this approach show how the tool provided and will continue to provide governmental agencies with the scientific basis for building eco-social resilience to climate warming into agricultural systems across the Mediterranean Basin and elsewhere.

Ponti L., Gutierrez A.P., Iannetta M., 2016. Climate change and crop-pest dynamics in the Mediterranean Basin. ENEA Technical Report, 27: 18 pp., | Open access

Growth rates of a crop, pest and natural enemy plotted on temperature to intuitively illustrate how an increase in average temperature from T0 to T+2°C may affect the physiological basis of trophic interactions. With temperature warming, biological control of the pest may decrease due to the narrower temperature tolerance of the natural enemy compared to the pest.

Invasiveness of spotted wing Drosophila

September 10, 2016 Leave a comment

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 Basin. Our focus is on areas of recent invasion and of predicted higher invasiveness in these areas. Although the species is native to Asia and is of putative temperate origins, it has established in subtropical to north temperate zones worldwide where it infests a wide range of wild and domesticated berries and stone fruits. The model captures the observed phenology of D. suzukii at specific locations, as well as the potential geographic distribution and relative favorability across larger regions. The main limiting factor is cold winter temperature in northern areas, though high temperatures and low relative humidity may be limiting in arid areas. The effect of greater cold tolerance in winter morph adults is explored.

Gutierrez A.P., Ponti L., Dalton D.T., 2016. Analysis of the invasiveness of spotted wing Drosophila (Drosophila suzukii) in North America, Europe, and the Mediterranean Basin. Biological Invasions, | Full text free to view

Geographic distribution of  Drosophila suzukii in Europe.

Traditional farming and the Mediterranean diet

September 10, 2016 Leave a comment

The Mediterranean diet is described by the UNESCO Cultural Heritage of Humanity website ( as encompassing more than just food of the various cultures. These diets are embedded in bio-cultural landscapes that are at risk from global markets, industrial agriculture, invasive species and climate change, and yet little research aimed at conserving this Mediterranean agricultural heritage is being conducted. A focus on preserving traditional Mediterranean agricultural systems provides unique opportunities to link UNESCO-SCBD’s Joint Programme on Biological and Cultural Diversity (​) and FAO’s Globally Important Agricultural Heritage Systems initiative (GIAHS, with the goal of developing strategies and policy to preserve this heritage and the food production systems that are its basis for future generations. An important step in this direction is the development of holistic ecosystem-level assessments of the stability and resilience of traditional Mediterranean farming systems to evolving global change including climate change and shifting economic patterns and associated landscape transformations. A holistic approach is an important step to ensure ecologically sustainable development, conserve cultural identities, improve farming community livelihood, preserve agro-biodiversity and ensure the continued provision of vital ecosystem services for humanity.

Ponti L., Gutierrez A.P., Altieri M.A., 2016. Preserving the Mediterranean diet through holistic strategies for the conservation of traditional farming systems. In: Agnoletti M., Emanueli F. (eds.), Biocultural Diversity in Europe, Springer International Publishing, Switzerland: 453-469.

Linking UNESCO-SCBD’s Joint Programme on Biological and Cultural Diversity and FAO’s GIAHS initiative may help preserve the traditional Mediterranean agricultural heritage.

Indian cotton: weather, yields and suicides

August 28, 2015 Leave a comment

Cotton with coevolving pests has been grown in India for more than 5000 years. Hybrid cotton was introduced in the 1970s with increases in fertilizer and in insecticide use against pink bollworm that caused outbreaks of bollworm. Hybrid Bt cotton, introduced in 2002 to control bollworm and other lepidopteran pests, is grown on more than 90 % of the cotton area. Despite initial declines, year 2013 insecticide use is at 2000 levels, yields plateaued nationally, and farmer suicides increased in some areas. Biological modeling of the pre-1970s cotton/pink bollworm system was used to examine the need for Bt cotton, conditions for its economic viability, and linkage to farmer suicides. Yields in rainfed cotton depend on timing, distribution, and quantity of monsoon rains. Pink bollworm causes damage in irrigated cotton, but not in rainfed cotton unless infested from irrigated fields. Use of Bt cotton seed and insecticide in rainfed cotton is questionable. Bt cotton may be economic in irrigated cotton, whereas costs of Bt seed and insecticide increase the risk of farmer bankruptcy in low-yield rainfed cotton. Inability to use saved seed and inadequate agronomic information trap cotton farmers on biotechnology and insecticide treadmills. Annual suicide rates in rainfed areas are inversely related to farm size and yield, and directly related to increases in Bt cotton adoption (i.e., costs). High-density short-season cottons could increase yields and reduce input costs in irrigated and rainfed cotton. Policy makers need holistic analysis before new technologies are implemented in agricultural development.

Gutierrez A.P., Ponti L., Herren H.R., Baumgärtner J., Kenmore P.E.. 2015. Deconstructing Indian cotton: weather, yields, and suicides. Environmental Sciences Europe, 27: 12. | Open access

Simulated phenology of cotton fruiting and pink bollworm in irrigated and rainfed cotton during 2005. The movement of adults to rainfed cotton during late summer is indicated by the broad arrow.

Agrobiodiversity in a changing world

July 19, 2015 Leave a comment

Exotic species that invade new areas cause economic loss annually nearly tenfold that of natural disasters. The economic impact of such biological invasions has been considerable also in agriculture, with many major agricultural pests being invasive species, which number is expected to increase given the combined action of climate warming and globalization, particularly in the Mediterranean Basin. This region is rich in natural and agricultural biodiversity but also considerably vulnerable to biological invasions that threaten key elements of Mediterranean agro-biodiversity such as the traditional perennial crops grape and olive. Currently, most major threats to grape and olive culture are invasive species – often vector borne diseases so serious that the only control method is removal and destruction of infected crop plants. However, how to assess the potential impact of such invasive threats, and hence how to manage them, remains an unresolved and largely unexplored problem. Gaps exist between theory and management of invasive species, mostly due to a limited ability to assess their ecological and economic impact. Mechanistic process-based demographic approaches such as physiologically-based demographic models (PBDMs) have the capacity to bridge these gaps, as they address many of the shortcomings that affect mainstream methods currently used to assess invasive species under climate change.

Ponti L., Gutierrez A.P., 2015. Climate change and invasive species, with a particular focus on vine and olives. A (bio) diverse world: agro-biodiversity in a changing world, EXPO Milano 2015, Milano, Italy, 6 May 2015.