the GlobalChangeBiology blog

Background. The implementation of hybrid Bt cotton unique to India has been heralded as a grand success by government agencies, seed companies and other proponents, and yet yields have stagnated at low levels and production costs have risen 2.5–3-fold. The low-yield hybrid cotton system of India contributes thousands of farmer suicides to the annual national toll. Conceptual and methodological barriers have hindered bioeconomic analysis of the ecological and social sustainability of such cross-scale agro-ecological problems in time and geographic space, under global technology and climate change. As a paradigm shift, we use conceptually simple, parameter-sparse, theoretically based, mechanistic, weather-driven physiologically based demographic models (PBDMs) to deconstruct the bio-economics of the Indian cotton system. Results. Our analysis of Indian hybrid cotton system explains some extant ecological and economic problems, and suggests a viable solution. Specifically, the model accur...

 Coffee, after petroleum, is the most valuable commodity globally in terms of total value (harvest to coffee cup). Here, our bioeconomic analysis considers the multitude of factors that influence coffee production. The system model used in the analysis incorporates realistic field models based on considerable new field data and models for coffee plant growth and development, the coffee/coffee berry borer (CBB) dynamics in response to coffee berry production and the role of the CBB parasitoids and their interactions in control of CBB. Cultural control of CBB by harvesting, cleanup of abscised fruits, and chemical sprays previously considered are reexamined here to include biopesticides for control of CBB such as entomopathogenic fungi (Beauveria bassiana, Metarhizium anisopliae) and entomopathogenic nematodes (Steinernema sp., Heterorhabditis). The bioeconomic analysis estimates the potential of each control tactic singly and in combination for control of CBB. The analysis explains ...

There is no doubt that humanity needs an alternative agricultural development paradigm, one that encourages more ecologically sound, biodiverse, resilient, sustainable, and socially just forms of agriculture. The basis for such new systems are the myriad of ecologically based agricultural styles developed on hundreds of millions small farms that produce a large share of the food consumed today in the world, mostly without agrochemicals. Agroecology represents this paradigm: a dialogue of wisdoms between traditional agricultural knowledges and modern agricultural sciences that uses ecological concepts and principles for the design and management of sustainable agroecosystems where external inputs are replaced by natural processes. This international Agroecology short course was held from May 2nd to 5th, 2018 at the Center for “Climate Change and Biodiversity in Lakes and Wetlands” located on Polvese Island , Lake Trasimeno, Umbria (Italy), and was designed for scholars, students, farmer...

( This paper made cover story .) Of fruit crops, grape is the most largely cultivated and has the highest economic importance globally; it is part of the Mediterranean bio-cultural heritage that is threatened by climate change. However, the analysis of the climate effects on grape and other crop and natural ecosystems on a regional scale has been vexing. Here, we review how sparse physiologically based demographic models (PBDM) in the context of the geographic information system GRASS GIS can be used to examine the effects of the extant weather and climate change on the dynamics of the interaction between grape and European grapevine moth across the Euro-Mediterranean region. Further, by including management-relevant complexity in a mechanistic way, the PBDM/GIS system provides the basis for a regional bioeconomic analysis of the grape system and a template for similar analyses that require modest data and funding. Ponti L., Gutierrez A.P., Boggia A., Neteler M., 2018. Analysis of ...

Climate change is impacting agroecosystems widely. Ecological connectivity makes regions more resilient and hence helps conserve biodiversity and combat climate change, while ecologically sound analysis and management help keep agroecosystems alive. In this context, a bioeconomic approach may help guide the integration of natural and human systems. In Umbria, the origin of this approach was the opening lecture of TreviNatura (Trevi, Italy 25-27 October 2015) delivered by Professor Andrew P. Gutierrez ( CASAS Global ) and titled  " The economy of nature and humans: the role of ecosystem services " that illustrated the often conflicting interaction between humans and nature, and how this interaction can be best understood using bioeconomics, with ecosystem services playing a central role. The region of Umbria in Central Italy is particularly amenable to developing and implementing a holistic approach to the integrated management of agricultural and natural ecosystems, because t...

This paper is a critique of Srivastava and Kolady (Current Science, 2016; 110: 3-10) who reported a macro analysis of the benefits of Bt cotton in India using statewide average data. The analysis is in error with respect to the economic benefits, biological underpinnings, and the effects of Bt cotton technology adoption on resource-poor farmers growing rainfed cotton. Viable non-GMO high-density cotton alternatives that increase yields, reduce cost of production, and give higher net average returns were ignored. The authors argue for biotechnology adoption in other crops in India without providing data or analysis Gutierrez A.P., Ponti L., Baumgärtner, J., 2017. A critique on the paper ‘Agricultural biotechnology and crop productivity: macro-level evidences on contribution of Bt cotton in India’. Current Science, 112: 690-693. Full text free to download Trends for cotton yield, pesticide use and the percentage of total cotton growing area planted to Bt cotton.

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...

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 irrigat...

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 ...

Inability to determine reliably the direction and magnitude of change in natural and agro-ecosystems due to climate change poses considerable challenge to their management. Olive is an ancient ubiquitous crop having considerable ecological and socioeconomic importance in the Mediterranean Basin. We assess the ecological and economic impact of projected 1.8 °C climate warming on olive and its obligate pest, the olive fly. This level of climate warming will have varying impact on olive yield and fly infestation levels across the Mediterranean Basin, and result in economic winners and losers. The analysis predicts areas of decreased profitability that will increase the risk of abandonment of small farms in marginal areas critical to soil and biodiversity conservation and to fire risk reduction. Ponti L., Gutierrez A.P., Ruti P.M., Dell’Aquila A., 2014. Fine scale ecological and economic assessment of climate change on olive in the Mediterranean Basin reveals winners and losers. Procee...

The use of marginal land (ML) for lignocellulosic biofuel production is examined for system stability, resilience, and eco-social sustainability. A North American prairie grass system and its industrialization for maximum biomass production using biotechnology and agro-technical inputs is the focus of the analysis. Demographic models of ML biomass production and ethanol farmer/producers are used to examine the stability properties of the ML system. A bio-economic model that maximizes the utility of consumption having the dynamics of MLs and the farmer/producers as dynamic constraints is used to examine the effects of increased conversion efficiency, input costs, risk, and levels of base resources and inputs on the competitive and societal solutions for biomass production. We posit ML abandonment after biofuel production ceases could lead to permanent land degradation below initial levels that prohibit the establishment of the original flora and fauna. Gutierrez A.P., Ponti L., 2009. ...