The economics of pest management

Abstract

When is a pest a pest? Children are at times called pests, while at other times we call them darlings. Possums were, not so long ago, considered a resource to New Zealand society, in that they provided skins and recreational opportunities. The annual report of the Auckland Acclimatization Society 1916-1917 stated.     

The economics of bird migration

Piersma, T. 2000. The economics of bird migration. Ostrich 71(1): 362.

Through their migrations birds spin a worldwide web of migratory routes. Even at the level of individuals and populations, the migrations can cover a large part of the globe. Many factors are involved in the evolution and maintenance of all these migration systems: the contingencies of earth history, the sensory and metabolic evolutionary potential of flying organisms, the distribution of predators and parasites, and energetic considerations. In this presentation I aim to briefly outline the use of energetics in studies on the maintenance of today's flyways. My overview will focus on the shorebird species seasonally migrating between wintering grounds in coastal African and the breeding grounds in the Canadian, Greenlandic, European and Siberian Arctic.

Every individual animal has to balance its energy budget but depending on size, it can balance the discrepancies between energy expenditure and energy intake through the use or storage of nutrients at various time scales. Energy thus provides a common currency to relate ecological phenomena that are separated in space and time. I will describe methods to estimate energy expenditure, energy intake and the use of energy stores, and how these estimates can be translated as an annual energy budget of a coastal shorebird species. This will then be used to evaluate the repercussions of wintering at tropical latitudes and at temperate latitudes, and how such knowledge might help us to understand the evolution of a migration system. Population-specific energy budgets provide only one of the possible uses of energetics approach. Studies at the individual level, at which it is rarely possible to quantify such budgets completely, nevertheless benefit from energetic considerations when the functional significance of variations in migratory timing and seasonal body mass and plumage changes are the focus of attention.     

The evolutionary economics of immunity

How much of its resources should an individual invest in a costly immune system? In this article, we apply an evolutionarily stable strategy analysis to an epidemic model to answer this question. On the one hand, an investment in immune function confers protection to infectious agents by reducing host susceptibility, pathogen virulence, or the length of the infectious period. On the other hand, an immune system is costly since it absorbs resources that otherwise might be invested in increasing the host's fertility or longevity. In addition, an active immune system may be able to clear pathogens efficiently but at the same time may result in immunopathology. By means of a reproductive value approach, we show how to compare the costs and benefits of an immune system systematically and how to derive the evolutionarily stable level of immune function. We then apply these methods to various plausible scenarios. The analysis reveals that the relationship between the life span of an organism and the optimal level of investment in immune function is less straightforward than one might expect. First, the prevalence of infection is reduced to the lowest possible level only under special circumstances. Second, members of a long-lived species do not necessarily have to invest more in immune function than those of a short-lived species. In fact, the opposite may be true. Third, the outcome of evolution can be contingent on the initial conditions. Depending on its initial investment strategy, a population may evolve to a state where very much or almost nothing is invested in a costly immune system.     

The conditional economics of sexual conflict

Sexual conflict is a fundamentally important aspect of male–female interactions. In this opinion piece, we emphasize two approaches that warrant significantly greater attention. First, we review the importance of understanding the ‘economics’ (costs and benefits) of sexual interactions and note surprisingly large, unrecognized gaps in our knowledge. Second, we highlight the novel obstacles and opportunities afforded by the dependence of sexually antagonistic (SA) selection on both the local environment and condition of the interacting individuals. We conclude that more research in these two areas is essential to fully understand the evolution of SA interactions and will provide significant new insights into the extent to which coevolution of the sexes is shaped by conflict. We argue that these approaches, although not new to the field, are undervalued and under-represented.     

The economics of inclusion body processing

Many recombinant proteins are often over-expressed in host cells, such as Escherichia coli, and are found as insoluble and inactive protein aggregates known as inclusion bodies (IBs). Recently, a novel process for IB extraction and solubilisation, based on chemical extraction, has been reported. While this method has the potential to radically intensify traditional IB processing, the process economics of the new technique have yet to be reported. This study focuses on the evaluation of process economics for several IB processing schemes based on chemical extraction and/or traditional techniques. Simulations and economic analysis were conducted at various processing conditions using granulocyte macrophage-colony stimulating factor, expressed as IBs in E. coli, as a model protein. In most cases, IB processing schemes based on chemical extraction having a shorter downstream cascade demonstrated a competitive economic edge over the conventional route, validating the new process as an economically more viable alternative for IB processing.     

The economics of current and future biofuels

This work presents detailed comparative analysis on the production economics of both current and future biofuels, including ethanol, biodiesel, and butanol. Our objectives include demonstrating the impact of key parameters on the overall process economics (e.g., plant capacity, raw material pricing, and yield) and comparing how next-generation technologies and fuels will differ from today’s technologies. The commercialized processes and corresponding economics presented here include corn-based ethanol, sugarcane-based ethanol, and soy-based biodiesel. While actual full-scale economic data are available for these processes, they have also been modeled using detailed process simulation. For future biofuel technologies, detailed techno-economic data exist for cellulosic ethanol from both biochemical and thermochemical conversion. In addition, similar techno-economic models have been created for n-butanol production based on publicly available literature data. Key technical and economic challenges facing all of these biofuels are discussed.