Recent studies have shown that genetic polymorphisms play an important role in structuring the seasonal life cycles of insects, complementing an earlier emphasis on the effects of environmental factors. This book presents current ideas and recent research on insect life--cycle polymorphism in a series of carefully prepared chapters by international experts, covering the full breadth of the subject in order to give an up-to-date view of how life cycles are controlled and how they evolve. By consolidating our view of insect life--cycle polymorphism in this way, the book provides a staging point for further enquiries. The volume will be of interest to a wide variety of entomologists and other biologists interested in the control and evolution of life cycles and in understanding the extraordinarily complex ecological strategies of insects and other organisms.

This book was developed out of a symposium at the XVII International Congress of Entomology held in Hamburg, Germany, on August 21, 1984. This symposium was organized by Drs. William Bradshaw and Hugh Dingle, who subsequently asked us to edit the proceedings. The chapters represent, for the most part, papers that were read in Hamburg but have been expanded and updated. The goal of this volume is to provide a comprehensive view of current research on insect life cycles, including field and laboratory studies, broad comparisons among species or local populations, and intensive studies of single populations, as well as theoretical research. Of necessity, given the magnitude of research now being carried out on insects, some important research programs are not included, and therein lie the makings of future volumes. This volume is divided into three parts. The first part, Geographical Patterns in Insect Life Cycles, explores various applications of a comparative method that has been valuable in investigating the potential for variability in life history parameters and the relation of these parameters to important variables in the environment.

No International Congress of Entomology would now be complete without a symposium on insect life-cycles. The latest Congress, held at Vancouver, BC (Canada), in July 1988, was no exception, with a symposium on the genetics, evolution, and coordination of insect life cycles organized by Bill Bradshaw and Valerie Brown. The present volume arose from papers contributed by most of the speakers at the symposium, together with papers from other invited authors. In editing the book, I have been assisted greatly by the other authors, particularly Bill Bradshaw, Val Brown and Fritz Taylor. All contributors agreed to referee two other chapters, a system that worked efficiently and effectively: I thank all authors for performing this task in the face of other demands on their time. I would also like to thank Philip Corbet, John Greenslade, Bryan Clarke, and Gillian Thompson of Springer for their help. Nottingham Francis Gilbert January 1990 Contents List of Contributors ....................................................... xiii SECTION I. Genetics of Life-Cycle Traits Introduction William E. Bradshaw ................................................. 3 1 Understanding the Evolution of Insect Life-Cycles: The Role of Genetic Analysis.

This review of literature includes an introduction on the origin of the olive tree and lists 116 species of insects and 30 species of mites known to infest it. It treats the geographical distribution, host plants, feeding habits, voltinism and seasonal history of 34 species of phytophagous insects as well as of 7 species of mites. Most of these are monophagous or oligophagous and closely associated with the olive tree. Of the species covered, 16 are Homoptera, one Hemiptera, one Thysanoptera, five Coleoptera, four Diptera, seven Lepidoptera, six Eriophyoidea and one Tetranychoidea. The review shows that all species, except one, have a seasonal dormancy and for most of them diapause is certain or reasonably suspected to occur. Seasonal displacement does occur in a number of species, especially shortly before or after dormancy. Differences of opinion on seasonal history between authors are pointed out and conclusions drawn based on the most convincing papers. Suggestions are made for further research on important, yet neglected aspects of the life history of olive arthropods.

This volume results from a symposium entitled "Species and Ufe History Patterns: Geographic and Habitat Variation", held during the National Meeting of the Entomo logical Society of America in Denver, Colorado, USA in November, 1979. The stimu lus to assemble papers on this theme emerged from continuing discussions with col leagues concerning controversies in ecology and evolutionary biology, namely those associated with plant-herbivore interactions, life history theory, and the equilibrium status of communities. The study organisms used in this series of reports are all either herbivorous insects or those intimately associated with plants. In this volume we stress the variation found in life history traits and address some of the problems inherent in current life history theory. We include as life history traits not only traditional variables such as fecundity, size of young, and age to first and peak reproduction, but also diapause and migration, traits that synchronize reproduction with favorable plant resources. Because life history traits of phytophagous insects are influenced in part by spatial and temporal variation in the quality and availability of their host plants, we also consider the role that dis continuities in plant quality play in reducing insect fitness. Lastly, much of the tra ditional life history theory concerns itself with differences between the evolution of traits or constellations of traits when populations incur primarily density-independent, compared to density-dependent, mortality. Consequently, we address this issue and attempt to shed light on the equilibrium status of several phytophagous insect com munities.

Many insects hatch from eggs and molt several times as they grow bigger. Others, such as butterflies, undergo a complete metamorphosis. A common science curriculum topic, insect life cycles may be confusing because of these differences. However, this book breaks down these cycles into easy-to-understand steps in both accessible language and colorful diagrams readers can turn to for review again and again. The most important vocabulary needed to talk about insect life cycles is further explained in fact boxes and an extended glossary.

It is difficult for me to recollect a time when I was not fascinated with the very notion of a desert. Walt Disney's film, The Living Desert, which I initially saw when I was 8 years of age, provided me with my first glimpse of this wondrous yet seemingly ho stile environment. The images were hypnotic and captivating. I looked on in amazement at the promenade Cl deux of the male and female scorpions during courtship. Their rhythmic and coordinated movements as they grasped one another made them appear to glide in unis on over the surface of the sand, each individual totally absorbed with its partner. In the next minute the fern ale had suddenly and utterly transformed herself like some Jekyll and Hyde act, into an aggressive predator whose prior gregarious embrace was now a hold of death for the male. The indomitable desert grasshopper mouse, the ever sentient kit fox, the graceful shovel-nosed snake swimming in an endless sea of sand.