Insect Diets: Science and Technology, 2nd edition

Abstract

In large measure, the success of entomology over the past century is founded on our ability to rear insects on artificial diets. Much of future entomology will likely continue to depend on diet-based programs. This reliance underscores the need to understand how and why diets work and how and why they fail. In more than three decades of research in entomology, I have found that insect diets constitute one of the most complex, misunderstood, and underappreciated aspects of entomology. This book is written to help explain these complexities and dynamics. Unlike the handful of other texts on this subject, this book is not a compendium of diet formulations. Instead, it is an effort to explain what the various ingredients and processing steps do to make diets work. It explains the nutrient classes and how foods and diet components meet the insects’ nutritional and other feeding needs. The book explains diets in terms of overall insect feeding biology (feeding stimuli, digestion and absorption, and metabolic frameworks). It explains the effects of various processing steps used in preparation of components and complete diets, including refinement of foods, size reduction, heat and cold processing, prevention of microbial contamination and removal of antinutrients. It deals with the chemical and physical interactions of components, explaining how insect diets are matrices or dispersions with complex organization that predetermines the diets’ food value and stability. This book offers perspective on how diets are developed and how a program of quality assessment can be applied to rearing systems. The book draws heavily from food science and technology because the base of knowledge of these fields is highly advanced in developing a base of understanding of virtually every aspect of foods—their chemistry, physics, microbiology, and the effects of processing techniques. My personal “discovery” of food science was an epiphany that was like a biologist who had squinted at specimens for years trying to see minute structures and then discovered the existence of microscopes! I have found in the food science community an energetic quest to understand foods, and between the vast resources underpinning such studies and an atmosphere of open-minded inquiry, there is a wealth of information and methods for all of us dedicated to insect diets. In the movie Inherit the Wind about the Scopes trial, a sarcastic reporter quipped that religion’s purpose was “to comfort the afflicted and to afflict the comfortable.” In a very real sense, that is also the purpose of this book. I have found that the complexity and difficulty in developing and using artificial diets properly have been greatly underestimated, and those who perform these practices competently have been underappreciated. In this light, I have tried to fill in the gaps in understanding for those who work with insect diets and to illustrate for everyone connected with insect diets how complex and special these tools actually are. To “afflict the comfortable,” I have tried to explain the many pitfalls that result from complacency and oversimplification of the complex dynamics of diets; to “comfort the afflicted,” I have provided explanations of why we use the specific ingredients and processing steps called for in diet formulations and how to anticipate and troubleshoot problems with diets. The driving force behind this book is the demystification of insect diets as “black boxes” whose mechanisms and modes of action have been obscure. I hope, once the scientific and mechanistic basis is clear regarding how diets work or fail to work, the community of rearing and diet specialists will be better equipped to develop new diets and to improve their efficiency in handling established diets. Such improvements will serve the entomology community as a whole by making available increased numbers of various species of insects produced under conditions that are, at once, quality enhancing and economical. I most hope this book will be a bridge for rearing specialists and their stakeholders to use artificial diets as ever-improving tools to better manipulate insects in ways that benefit humanity and our environment.