Insecticide Action

Insecticide Mode of Action presents significant research on the biological activity of insecticides. The book is organized into three sections encompassing 13 chapters that summarize three major groups of insecticides, including neurotoxic, formamidine, and developmental insecticides. The first section of the book presents studies on groups of conventional neurotoxic insecticides: chlorinated hydrocarbons, pyrethroids, carbamates, and organophosphorus chemicals. This text discusses their structure, poisoning property, structure-activity relationships, and stereoselectivity. The subsequent section discusses the biochemical, biological, and neurotoxic actions of formamidines, a group of pesticides that exhibit an unusual spectrum of activity. Several modes of action of pharmacological significance as well as some important behavioral effects are included in this section. The third section addresses groups of insecticides that affect insect growth and development. Such chemicals typically demonstrate marked selectivity and represent more sophisticated strategies in the chemical control of insect pests. This book is of value to researchers, teachers, and regulatory personnel concerned with the biological activity of insecticides.

Intoxication of humans and animals has become increasingly important in recent years as has contamination of the environment by a variety of chemicals. In order to develop effective means by which such intoxication and contamination can be properly handled, it is imperative to know how these environmental agents act in humans and animals. Despite studies conducted by various investigators, the mechanisms of action of these environmental agents have not been fully elucidated. Insecticides are by no means an exception in terms of the seriousness of the problem and of the urgency of the need for such information. In order to complete a picture of the effects of any particular insecticide, it is of utmost importance that its actions at various levels ranging from those of molecules to whole animals be analyzed and synthesized. To understand the toxicological action on animals or humans, it is not sufficient to know the action at each level only. The actions at various levels must be integrated to construct a picture of the toxic effect on the intact organism. However, in spite of the large body of information that has been accumulated during the past few decades, little or no attempt has been made to integrate experimental data obtained at the molecular, cellular, organ, and animal levels together in order to define the whole picture of insecticidal action.

The future of insect control looked very bright in the 1950s and 1960s with new insecticides constantly coming onto the market. Today, however, whole classes of pesticide chemistry have fallen by the wayside due to misuse which generated resistance problems reaching crisis proportions, severe adverse effects on the environment, and public outcry that has led to increasingly stricter regulation and legislation. It is with this background, demanding the need for safer, environmentally friendly pesticides and new strategies to reduce resistance problems, that this book was written. The authors of the various chapters have a wealth of experience in pesticide chemistry, biochemical modes of action, mechanism of resistance and application, and have presented concise reviews. Each is actively involved in thedevelopment of new groups of pesticide chemistry which led to the development of novel insecticides with special impact in controlling agricultural pests. Emphasis has been given to insecticides with selective properties, such as insect growth regulators hormone mimics, ecdysone agonists), (chitin synthesis inhibitors, juvenile chloronicotinyl insecticides (imidacloprid, acetamiprid), botanical insecticides (neem, plant oils), pymetrozine, diafenthiuron, pyrrole insecticides, and others. The importance of these compounds, as components in integrated pest management programs and in insecticide resistance management strategies, is discussed. The data presented are essential in establishing new technologies and developing novel groups of compounds which will have impact on our future agricultural practices.

In recent years many of the conventional methods of insect control by broad spectrum synthetic chemicals have come under scrutiny because of their unde sirable effects on human health and the environment. In addition, some classes of pesticide chemistry, which generated resistance problems and severely affected the environment, are no longer used. It is against this background that the authors of this book present up-to-date findings-relating to biochemical sites that can serve as targets for developing insecticides with selective prop erties, and as the basis for the elucidation of resistance mechanisms and countermeasures. The book consists of eight chapters relating to biochemical targets for insec ticide action and seven chapters relating to biochemical modes of resistance and countermeasures. The authors of the chapters are world leaders in pesti cide chemistry, biochemical modes of action and mechanisms of resistance. Biochemical sites such as chitin formation, juvenile hormone and ecdysone receptors, acetylcholine and GABA receptors, ion channels, and neuropeptides are potential targets for insecticide action. The progress made in recent years in molecular biology (presented in depth in this volume) has led to the iden tification of genes that confer mechanisms of resistance, such as increased detoxification, decreased penetration and insensitive target sites. A combina tion of factors can lead to potentiation of the resistance level. Classifications of these mechanisms are termed gene amplification, changes in structural genes, and modification of gene expression.

Insecticides: Action and Metabolism provides a comprehensive review of the action of insecticides and a survey of their metabolism. This book discusses the toxicology of insecticides. Organized into 17 chapters, this book begins with an overview of the mechanisms whereby toxicants exert their effects. This text then discusses the insecticidal action of organophosphates, which is described as the toxic organic compounds containing phosphorus. Other chapters consider the mode of action of organophosphates by inhibiting cholinesterase with consequent disruption of nervous activity caused by accumulation of acetylcholine at nerve endings. This book discusses as well the erratic patterns of selective toxicity to insects of the carbamates. The final chapter deals with the real hazard to human health as well as the effects upon wild life of insecticides and chlorinated pesticides. This book is a valuable resource for organic and agricultural chemists, as well as biologists, agriculturists, neurophysiologists, environmental scientists, and research workers.

Environmental-friendliness, issues of public health, and the pros and cons of genetically-modified crops all receive regular coverage in the world's media. This, in turn, has led to increased questioning and investigation of chemical pesticides. Stenersen's concise and timely introduction to chemical pesticides describes these compounds according to their mode of action at the cellular and biochemical level. Chemical Pesticides provides answers to questions such as why pesticides are toxic to the target organism and why pesticides are toxic to some organisms and not others. It describes how various poisons interfere with biochemical processes in organisms. The book also explores how resistance to pesticides develops, how resistance can be used to illustrate the theory of evolution, and how it can be used to produce herbicide-resistant crop plants. Legal matters and potential environmental problems are also discussed. By providing an integrated, yet simple description of modern chemical pesticides, the author provides a relevant text for professionals and students in biological disciplines such as biochemistry, medicine, agriculture, and veterinary science.

Only four short decades ago, the control of insect pests by means of chemicals was in its early infancy. The pioneers in the area consisted largely of a group of dedicated applied entomologists working to the best of their abilities with a very limited arsenal of chemicals that included inorganics (arsenicals, fluorides, etc.), some botanicals (nicotine), and a few synthetic organics (dinitro-o-cresol, organothiocyanates). Much of the early research was devoted to solving practical problems associated with the formulation and application of the few existing materials, and although the discovery of new types of insecticidal chemicals was undoubtedly a pipe dream in the minds of some, little or no basic research effort was expended in this direction. The discovery of the insecticidal properties of DDT by Paul Miiller in 1939 has to be viewed as the event which marked the birth of modern insecticide chemistry and which has served as the cornerstone for its subse quent developement. DDT clearly demonstrated for the first time the dramatic potential of synthetic organic chemicals for insect control and provided the initial stimulus which has caused insecticide chemistry to become a field not only of immense agricultural and public health importance but also one that has had remarkable and unforseeable repercussions in broad areas of the physical, biological, and social sciences. Indeed, there can be few other synthetic chemicals which will be judged in history to have had such a broad and telling impact on mankind as has DDT.