Margaret Redfern
HarperCollins Publishers, London
2011; 562 pages
ISBN: 978-0-00-220144-5 (paperback), ISBN: 978-0-00-220148-8 (hardcover)
Price: £30 (softcover), £50 (hardcover)

The Collins New Naturalist Library is now in its 66th year, having started in 1945 with the publication of E.B. Ford’s Butterflies, and has covered numerous entomological subjects since then, such as volumes on moths, dragonflies, ants, ladybirds, insect migration, and the pollination of flowers.  Now, in Number 117, we have Plant Galls by Margaret Redfern, as an addition to this long series of books that survey British natural history.  While focusing on British plant galls, the scope of the book addresses the phenomenon of galling in a comprehensive way, including international treatment of the literature.  Many taxa discussed are Holarctic in distribution at the generic level, making much information directly relevant to the American audience.  For example, among the gall-inducing sawflies, all species are in the same genera around the northern hemisphere.  The book is intended to encourage amateur naturalists to study galls in their own locality, and to provide professional biologists with an introduction to this area of plant and herbivore interactions.
 

After an introduction on the nature of galls, the book is divided into three parts covering the types of galls initiated by many kinds of insects, plus mites, fungi, bacteria, and viruses: Part 1, virescences and solid galls; Part 2, open galls; and Part 3, closed, chambered galls.  Each part is comprised of two or three chapters, such as Part 3, which is made up of chapters on flowerhead galls, galls on stems and roots, and galls in buds, leaves, and fruits.  A fourth part is titled “Galls in Context” with chapters on the ecology, evolution, and biogeography of galls, as well as chapters on “Galls and People,” and “Galls in History.” The end pages include a glossary, appendices on the kinds of gall inducers, host plants, the third trophic level of enemies and inquilines of gallers, general references, and references for each chapter, plus species and subject indices.  This comprehensive treatment is greatly embellished by a rich selection of high-quality color photographs, line drawings, and diagrams, which contribute to the education and pleasure provided in this book.
 

The author, Dr. Margaret Redfern, has been interested in plant galls for much of her adult existence, and teaches at Sheffield University in the United Kingdom.  She is a well-known author, extensively published in the fields of insect gall natural history, gall identification, ecology, and the historical literature on galls, all subjects well represented in this book.  At first mention of a gall-inducing taxon, boxed text provides a synopsis of the systematics and biology of the group, and in later chapters a box may contain recipes for writing inks using galls, galls studied by Theophrastus, or information on classification and cladistics.  These treatments, together with the extensive appendices and references, provide a scholarly approach while remaining attractive to the naturalist and the researcher alike.
 

The themes running through the first three parts of the book are gall structure and location on plant modules.  This makes the rich variety of galls immediately accessible to the novice, because such criteria can be appreciated easily, but it atomizes large families of inducers such as cecidomyiids and cynipids into many different parts of the book.  Other books on galls have been organized by host plant or gall-inducer family and species, providing a taxonomic theme more suitable, perhaps, for the experienced botanist or entomologist.  But a fascinating aspect of the phenomenon is the intimacy of the interaction, necessitating an appreciation of the plant and gall-inducer interaction.  The gall inducer acts as a parasite of the plant, with all the constraints and adaptive opportunities accompanying the parasitic mode of life.  In Chapter 1, we are informed that one estimate of gall-species richness recognizes about 133,000 species of insects and mites worldwide, representing a significant percentage of the insect fauna.  However, gall-inducers are inadequately studied throughout most of the world, providing opportunities for naturalists and professionals to easily discover new species and life histories.
 

As seen in several other groups with parasitic life styles, such as protozoa causing malaria and sleeping sickness and digenetic trematodes cycling between mammals or birds and insects, many gallers illustrate convergence to the heteroecious life cycle, moving between two host species to complete the life cycle, and between sexual and asexual forms of the same species.  Such complex life cycles are well illustrated in the book for gall-forming rusts, ergots, and other galling diseases caused by microorganisms, nematodes, aphids, adelgids, and gall wasps.  Another complexity rich with examples in the book is the diversity of organisms associated with galls.  An asexual cynipid gall on oak may support some 20 species of hymenopteran endo- and ecto-parasitoid and inquilines, and a sexual form of the same species another 10 or more species.Hence, the biodiversity on one oak tree, and the richness of interactions, escalates in a spectacular manner up the trophic system from host plant to gall inducer, to enemies and inquilines.  Therefor, one oak species may support several to many gall species, and a multitude at the third trophic level.  All this complexity and internecine confrontation builds throughout the book.

The naturalist will be fascinated and delighted by the extraordinary diversity of life histories, gall structures, and associated species, and the wonderful accompanying illustrations.  I am most enthusiastic in recommending this book to all entomologists and other naturalists.

Peter W. Price
Regents’ Professor Emeritus
Department of Biological Sciences
Northern Arizona University
Flagstaff, AZ, 86011
E-mail: Peter.Price@nau.edu

American Entomologist
Vol. 57, No.3, Fall 2011