Secret Weapons: Defenses of Insects, Spiders, Scorpions, and Other Many-Legged Creatures. Thomas Eisner, Maria Eisner, and Melody Siegler. Belknap Press, Cambridge, MA, 2005. 372 pp., illus. $29.95 (ISBN 0674018826 cloth).
Where as the general public is keenly aware of very obvious chemical defenses such as the venomous stings and bites of insects and related creatures, even many biologists are unaware of the full arsenal of defenses that insects and other arthropods use for protection from predation or parasitism. These defenses can assume a wide variety of forms, from passive defenses such as maintaining toxic compounds in the blood (or on the cuticle) to active defenses such as noxious stews of chemicals that are sprayed or wiped onto attackers. The origins of defensive compounds also vary widely, with some being sequestered or derived from host plants, whereas others are probably synthesized de novo. Overall, the literature on chemical defenses in arthropods is rather scattered, and so a single volume that presents a broad overview of the subject is long overdue. No one is better equipped for the task of assembling such a volume than Thomas Eisner, J. G. Schurman Professor of Chemical Ecology at Cornell University and one of the true pioneers in the field. He and his wife, Maria Eisner, along with neurobiologist Melody Siegler of Emory University, have produced a highly readable, entertaining, and lavishly illustrated book that presents a nice general summary of the subject.
This book is not a comprehensive scholarly tome, nor is it intended to be. Rather, the authors state in their prologue that Secret Weapons “is intended as an illustrated guide to the defenses of insects and their kin.” This idea works very well, particularly as the authors have personally worked on many of the species described, and thus can provide both spectacular photographs of the study organisms and all sorts of interesting details about various arthropods and their defensive systems. Within the context of this entertaining and readable format, the authors have provided key factual information about each system, including the full taxonomic names of the organisms, the names and chemical structures of the bioactive compounds, and pertinent references to the scientific literature. Thus, the book should appeal to a wide variety of audiences, from high school students in search of homework projects to biologists and research professionals seeking a general overview of the chemistry, tactics, and strategies of arthropod defense.
The book is organized primarily along taxonomic lines, rather than by the function of the defense (e.g., protection of eggs) or by classes of chemicals. It consists mainly of 69 brief chapters—each describing the chemical defenses of a particular species—bookended by a short prologue and epilogue, and a brief summary on the equipment and methods for studying insects and other small arthropods. Each chapter is essentially a vignette, giving a concise description of each organism, the chemicals that are found in its defensive secretions or sprays, and the mechanical, morphological, and behavioral adaptations that enable it to use its defenses effectively. The simple bioassays that the authors have developed for illustrating the nature of the chemicals involved in particular defenses are also nicely described. Throughout, rather than using the rather dry formalism of the scientific literature, the authors have adopted an informal, storytelling style, sprinkled with sidebar comments and brief digressions into discussions of related systems and examples. To some extent, it is like listening to an off-the-cuff narrative, with the authors' accumulated knowledge and experience leading to all sorts of fascinating parallels and connections as each story unfolds and leads into the next. Overall, this style draws the reader into the book; I could hardly wait to finish one example so that I could go on to the next.
However, what really makes each vignette come alive is the lavish use of color photographs, showing each animal in all its vivid glory. Even more remarkable are photos showing some of the various defenses in exquisite detail, such as droplets of secretions on the ends of glandular hairs, or the egg of a lacewing laid on a stalk, with the egg protected from predation by droplets of noxious secretions on the stalk (chapter 32). The latter example goes a step further by showing a subsequent photo of a newly hatched lacewing larva descending the stalk, imbibing the droplets as it goes for use in its own defense. (Nature is nothing if not parsimonious!) The clarity and vivid colors of the photographs of these tiny organisms, and the numerous other equally spectacular photos, would by themselves warrant purchase of this book. That they are intimately tied in with the factual text as illustrative examples of particular tactics and strategies only increases their worth.
The book is nicely indexed, with taxonomic names, common names, and chemical names all included, so that information about particular species, or the use of a specific chemical by one or more species, can be found readily. The text is well written, and virtually free of the typographical errors or other irritating mistakes that one sometimes sees in less professional volumes. To my knowledge, the factual information presented is accurate, with the single exception of the case of volicitin (chapter 57), which is described as a caterpillar salivary component that attracts parasitic wasps. The function of volicitin is actually more complicated, because it acts as an elicitor, inducing plants that are being attacked by herbivores to produce volatile chemicals that attract parasitic wasps, rather than being an attractant in its own right. It would also have benefited the reader to have citations supporting factual information in the text tied to the relevant articles, rather than simply listing all the articles used in developing each chapter at the end of that chapter. However, these are minor quibbles that do not seriously detract from a terrific book.
Overall, it is astonishing that the authors and publisher have been able to produce this remarkable volume in hardcover for a list price of under $30, particularly given the large number of photographs in brilliant colors. I highly recommend Secret Weapons as a good read for any organismal biologist, ecologist, or natural products chemist—or, for that matter, anyone with an interest in natural science. Volumes such as this, which bridge the gap between the general public and professional scientists, are both scarce and sorely needed. Given its content, quality, and relatively inexpensive cost, this book should find its way onto numerous bookshelves in both libraries and personal collections.