Jacques Brodeur and Guy Boivin, editors,
Springer, Dordrecht, The Netherlands, 2006,
249 pp., hardback, Price: $169.00, ISBN:101-4020-4766-5

Biological control of pests has traditionally focused on single predator-prey interactions, with the aim of selecting the most efficient natural enemy for a specific pest. However, there is increasing recognition that even in the most simplified agroecosystems, a wide variety of predators, alternative prey species, and plants are present, interacting within and among multiple trophic levels, and the results of these interactions can largely condition the success of biological control agents. This book successfully makes the case for the need to study these interactions to improve our design of biological control strategies. The authors of each chapter have contributed significantly to our knowledge of different aspects of these interactions, and they reflect that in this book using a diversity of approaches, including meta-analysis and review of the recent literature, case studies, theoretical models, and analysis of new data. The result is a well-balanced series of 10 chapters that explore the effects of intra- and interguild interactions such as predation, parasitism, disease, omnivory, competition, and mutualism on herbivore suppression.

The first four chapters focus mainly on intraguild (IG) trophic interactions, particularly in intraguild predation (IGP). The first chapter, by Rosenheim and Harmon, presents cross-study trends in how adding an IG predator to a system affects herbivore suppression and provides a nice summary of the history of the IGP concept and its use in biological control. The authors found omnivorous IG predators (i.e., those that consume herbivores and IG prey as independent events) are associated with decreases in herbivore populations, whereas coincidental IG predators (i.e., those that simultaneously consume herbivores and immature parasitoids within the herbivore as IG prey) are not. The second chapter, by Janssen et al., explored the same papers as in the first chapter, but emphasizes potential explanations for the discrepancies between theoretical predictions and empirical results. It provides a nice summary of the theoretical models that support IGP and discusses the influence of other ecological factors, such as productivity, on the outcome of IGP. Despite the different approaches followed in each chapter, there is considerable overlap and repetition in the conclusions. The third chapter, by Denno and Finke, assesses the effect of IGP on prey suppression by establishing the relationship of food web connectance and prey suppression within the arthropod community associated with Spartina cordgrass. Treatments with higher food web connectance (i.e., with a higher number of food web links because of the presence of IG predators) showed significantly lower prey suppression than treatments dominated by strict predators (i.e., predators that do not engage in IGP). However, when the same experimental food webs were established in a structurally complex environment (i.e., by adding thatch in experimental mesoscosms), prey suppression increased with predator richness because of a relaxation of intraguild predation by the presence of spatial refuges for IG prey. The chapter provides a very good introduction to the use of food web analysis in assessing the effects of multiple natural enemy assemblages in prey suppression. The fourth chapter, by Gillespie and Roitberg, explores the effects of plant quality and architecture mediating intra- and interguild interactions between strict and omnivorous predators. Using simple community tritrophic models, the authors showed short- and long-term effects of plant quality (defined by nutrient availability) and plant toxins on the outcomes of IGP and natural enemy population dynamics. A review of the literature confirms some of the model predictions and shows additional trends in plant architecture and kairomone production on IG predator-omnivore interactions.

The following six chapters cover a more diverse set of interactions and natural enemy groups. The fifth chapter, by Thomas et al., explores the patterns arising from their own research and the few available studies of multitrophic interactions involving host-pathogen/parasite interactions. Understanding these complex interactions among multiple hosts, pathogens, predators, and parasites can help to select more effective pathogens as biological control agents. In chapter 6, Boivin and Brodeur review the importance of understanding how flexible foraging behaviors of different parasitoids are affected by intra- and interspecific competition and hyperparasitic interactions. In chapter 7, van Veen et al. discuss the role of apparent competition in structuring ecological communities and in biological control. They draw examples from aphid-natural enemy systems that show the effects of apparent competition in biological control programs and point out that more research is needed into how apparent competition affects population suppression of both target and nontarget prey. In chapter 8, Eubanks and Styrsky present how the importance of ants as biocontrol agents is mediated by the availability of mutualistic hemipterans. Based on a literature review and their own studies, they conclude that the benefits of ants as biological control agents outweigh the adverse impact of higher hemipteran densities in cropland. In chapter 9, Mills summarizes the effects of interspecific competition on biological control using theoretical models and empirical results. From his discussion, it is clear that more studies that sequentially partition the multitude of extrinsic variables known to affect the outcome of these interactions are necessary. In the last chapter, Straub and Snyder assess how methods employed in biodiversity and ecosystem functioning studies complement and enhance methods currently used to assess multiple predator interactions and improve our understanding of how predator biodiversity contributes to biological control.

This book is highly recommended for researchers interested in biological control, predator ecology, trophic interactions, and insect ecology in general. After reading this book, it becomes clear that there is much to gain in expanding the traditional single predator-pest approach used in biological control to incorporate multiple interactions across guilds. It also highlights how solving applied problems with ecological principles simultaneously tests basic ecological principles. There is deep, concise, and clear coverage of the different subjects, as well as nice introductions to novel techniques that can be used to study these problems and comparisons of theoretical models with empirical data. Thus, this book is particularly suitable for a graduate level course on predator ecology and trophic interactions. The editing of the book is very careful, with helpful figures in each chapter, and a nice and compact format.

Alejandro C. Costamagna
Department of Entomology, University of Minnesota,
Saint Paul, Minnesota

Environmental Entomology
Vol. 38, No. 4, August 2009, Page 1343 – 1344