Suchergebnisse

Transgenic insecticidal Bt crops are being increasingly used worldwide, and concern is increasing about resistance and their effects on nontarget organisms. The toxin acts as a weak pesticide and, hence, the effects are subtler than those of chemical biocides. However, the toxin is ever present, but concentrations vary with age of plant and plant subunit, causing varying lethal and sublethal effects on pest survival, developmental time, and fecundity. Refuges for susceptibility to Bt occur spatially in non-Bt hosts and temporally within the crop because of time-varying toxicity and pest tolerance. Natural enemies feeding on Bt-intoxicated prey may have reduced longevity and, likely, fecundity that reduces their efficacy in controlling pest populations, and pest resurgence and secondary pest outbreaks may occur that may require insecticide use. System modeling is proposed as an efficient tool for examining the use of extant and future biotechnologies in pest control.

In light of the recently developed European Union (EU) Biofuels Strategy, the literature is reviewed to examine (a) the coherency of biofuel production with the EU nonindustrial vision of agriculture, and (b) given its insufficient land base, the implications of a proposed bioenergy pact to grow biofuel crops in the developing world to meet EU biofuel demands. The EU acknowledged that the use of food crops for biofuel production was based on wrong assumptions concerning climate change mitigation, and its support has now shifted to second-generation nonfood crops. The bioenergy pact entails (a) biofuel crops production in developing countries, especially Africa, that in the absence of environmental and social regulations may lead to ethical trade-offs in land use (food vs. fuel) and (b) the use of transgenic technology that conflicts with the EU's own vision of sustainable agriculture.

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.

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.

AbstractThis paper reviews the ongoing failure of hybrid transgenic Bt (Bacillus thuringiensis) cotton unique to India. The underlying cause for this failure is the high cost of hybrid seed that imposes a suboptimal long-season low plant density system that limits yield potential and has associated elevated levels of late-season pests. Indian hybrid Bt cotton production is further complicated by the development of resistance to Bt toxins in the key pest, the native pink bollworm (Pectinophora gossypiella Saunders, PBW), resulting in increased insecticide use that induces ecological disruption and outbreaks of highly destructive secondary pests. Rainfed cotton production uncertainty is further exacerbated by the variable monsoon rains. While hybrid cotton produces fertile seed, the resulting plant phenotypes are highly variable preventing farmers from replanting saved seed, forcing them to buy seed yearly (i.e., market capture), and effectively protecting industry Intellectual Property Rights (IPRs). The lessons gained from the ongoing market failure of hybrid Bt cotton in India are of utmost importance to its proposed introduction to Africa where, similar to India, cotton is grown mainly in poor rainfed smallholder family farms, and hence similar private–corporate conflicts of interest will occur. Holistic field agroecological studies and weather-driven mechanistic analyses are suggested to help foresee ecological and economic challenges in cotton production in Africa.High-density short-season (HD-SS) non-hybrid non-genetically modified irrigated and rainfed cottons are viable alternatives for India that can potentially produce double the yields of the current low-density hybrid system.

Tropical fruit flies are considered among the most economically important invasive species detected in temperate areas of the United States and the European Union. Detections often trigger quarantine and eradication programs that are conducted without a holistic understanding of the threat posed. Weather-driven physiologically-based demographic models are used to estimate the geographic range, relative abundance, and threat posed by four tropical tephritid fruit flies (Mediterranean fruit fly, melon fly, oriental fruit fly, and Mexican fruit fly) in North and Central America, and the European-Mediterranean region under extant and climate change weather (RCP8.5 and A1B scenarios). Most temperate areas under tropical fruit fly propagule pressure have not been suitable for establishment, but suitability is predicted to increase in some areas with climate change. To meet this ongoing challenge, investments are needed to collect sound biological data to develop mechanistic models to predict the geographic range and relative abundance of these and other invasive species, and to put eradication policies on a scientific basis.

An amendment to this paper has been published and can be accessed via the original article.

Abstract
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 accurately captured the age-stage mass dynamics of rainfed and irrigated cotton growth/development and the interactions with the key pest pink bollworm across five south-central Indian states, and enabled identification of proximate bioeconomic factors responsible for low yield and their relationship to farmer suicides. The results are reinforced by analysis of Ministry of Agriculture annual state-level data. We explain why short-season, high-density non-GM cotton is a highly viable solution for Indian cotton farmers in rainfed and irrigated cotton areas of the five states, and possibly nationally. The transition from a theoretical bioeconomic construct to a real-world regional bioeconomic analysis proved seamless.

Conclusions
The hybrid long-season Bt technology for rainfed and irrigated cotton is unique to India, and is a value capture mechanism. This technology is suboptimal leading to stagnant yields, high input costs, increased insecticide use, and low farmer incomes that increase economic distress that is a proximate cause of cotton farmer suicides. The current GM Bt technology adds costs in rainfed cotton without commensurate increases in yield. Non-GM pure-line high-density short-season varieties could double rainfed cotton yield, reduce costs, decrease insecticide use, and help ameliorate suicides. The GM hybrid technology is inappropriate for incorporation in short-season high-density varieties.