Preface

The widespread use of pesticides worldwide in agricultural production and for the control of disease vectors is an indicator of the cultivation status of different countries. With the growth in the global population and the concomitant intensification of agricultural production, pesticide overuse and contamination have also increased. The pesticide industry produces more than 800 active ingredients for the manufacture of over 40,000 commercial formulations used in the agricultural sector. Understanding of the unsafe usage of pesticides is increasing as the deleterious consequences for living species and the environment appear following occupational, accidental or incidental exposure to different types of pesticides. Environmental risk assessment associated with the production, storage and usage of pesticides has an important part to play in regulatory decisions. Existing and new compounds should be continuously evaluated to guarantee appropriate safety standards.

This book contains valuable information on diverse pesticides encountered in both anthropogenic and natural environments and covers the toxicity, efficacy and risk assessment of several compounds that can negatively influence the health of living species and ecosystems.

The book begins with a chapter on weed control strategies, describing innovative herbicide encapsulation methodologies with polymeric materials. Chapter 2 examines the use of several forms of chemical pesticide and their effects on sunflower cultivation and sunflower breeding. Strategies described include obtaining new genetic variability hybrids and sunflower varieties resistant to pests and chemicals. Chapter 3 describes strategies for the management of fungicidal resistance in potato pathogens, and discusses alternative cultural practices, the use of bio-agents and green chemicals, and the elimination of disease sources. Chapter 4 categorizes biomimetic and hemisynthetic pesticides according to their effect on one or more biological systems, including pesticides that target the nervous system, endocrine system, digestive system and various cellular structures in several insect groups. Chapter 5 considers pesticide toxicity in Tetranychidae mites (Chelicerata, Arachnida), and how sub-lethal concentrations of pesticides can significantly reduce the population growth, life expectancy and predation habits of Phytoseiid mites. The chapter also discusses the best strategies in integrated programmes for the biological control of pest populations. Chapter 6 reviews pesticides employed in the care of pets to control unwanted organisms such as ticks, fleas, and mites. The chapter highlights the advantages of applying pesticides as well as the harmful side effects that may be inflicted on animal companions. Chapter 7 describes the effect of simultaneous exposure to noise and pesticides on the hearing and vestibular systems of endemic disease control agents who worked on public health programmes. The results showed that some areas of the peripheral and central hearing system, as well as the peripheral vestibular system, are likely to be affected by exposure. Chapter 8 discusses the molecular effects of pesticides on haematological biomacromolecules, especially haemoglobin, as the target of organophosphates, carbamates, pyrethroids and neonicotinoids, among others. Chapter 9 examines the relationship

between the use of banned pesticides and the incidence of health conditions that affect people's quality of life in health, social and/or labour contexts in developing countries. Chapter 10 describes the toxicity analysis of active ingredients found in open markets in North Central Nigeria, showing how consumers used common active ingredients that were not approved for agricultural use in the area. Chapter 11 presents aspects of the chemistry, manufacture, import and regulation of pesticides in Kenya, as well as their usage and negative impacts on the environment. The chapter describes various categories of chemicals such as organochlorine, organophosphate, carbamate, pyrethroid and neonicotinoid insecticides, as well as fungicides, herbicides and biopesticides routinely used in Oriental African countries. Chapter 12 focuses on the application of nanotechnology and current methodologies for the efficient and rapid detection of residual carbamate pesticides in fruits and vegetables. Sensitive and selective pesticide detection techniques to facilitate detection without the need for complex equipment are discussed. The final chapter discusses the major exposure routes of pesticides in water bodies, mainly from agricultural sectors, and their effect on the ecosystem. Decontamination techniques to eliminate pesticide contaminants associated with adverse effects on humans and other life forms are described.

The editors of Pesticides - Updates on Toxicity, Efficacy and Risk Assessment are enormously grateful to all the authors who have contributed to this book. The contributions made by specialists in this field of research are gratefully acknowledged. We hope that the information presented here will continue to meet the expectations and needs of all those interested in the different aspects of pesticides.

The publication of this book is of great importance to those scientists, pharmacologists, physicians and veterinarians, as well as engineers, teachers, graduate students and administrators of environmental programmes, who are employing different investigations to understand both basic and applied aspects of the use and misuse of pesticides.

> **Sonia Soloneski, Ph.D. and Marcelo L. Larramendy, Ph.D.** School of Natural Sciences and Museum, National University of La Plata, La Plata, Argentina

> > **1**

**Chapter 1**

**Abstract**

chemical era of weed control.

**1. Introduction**

Polymeric Systems for the Delivery

Weeds are unwanted plants, which interfere with the crop production. Weeds compete with crops for resources, causing severe yield loss. Chemical weed control through herbicides is a quite effective and reliable strategy to manage weeds. Herbicides constitute a major share of the global pesticide market. However, the applied herbicides undergo losses in the agroecosystem in different ways (chemical degradation, microbial decomposition, photo-degradation, leaching, run-off, and volatilization), thus lowering the herbicidal action coupled with contaminating ecosystem and groundwater. Encapsulation of herbicides is an innovative approach that addresses issues associated with the application of herbicides for controlling weeds. Encapsulation represents the embedding of an active ingredient in shell of polymeric material to achieve the controlled release of the active ingredient at the desired rate. The encapsulation of herbicides enhances stability, solubility, and bioactivity and alters the release pattern of herbicide resulting in improved weed control efficiency. Further, encapsulation lowers the application rate of herbicides, which in turn reduces the residue carryover of herbicide in soil and minimizes the environmental hazards. Therefore, encapsulated herbicide formulation has greater significance in the future weed management and will become ground-breaking technology in the

of Herbicides to Improve Weed

Control Efficiency

*S. Marimuthu, P. Pavithran and G. Gowtham*

**Keywords:** weeds, herbicides, polymers, encapsulation, weed control

Weeds are as old as agriculture that influence crop growth and yield. Weeds compete with crops for resources such as space, water, nutrients, and light, which indirectly affect crop growth. Weeds inflicted tremendous yield loss besides deteriorating crop and grain quality, chocking water flow in an irrigation channel, sheltering crop pests, and causing ailments in living beings. The estimate on yield reduction due to weeds was one-third among agricultural pests [1]. The average loss in agricultural production due to weed infestation were 5, 10, and 25% in most developed, developing, and least developing nations, respectively [2]. Weeds cause a yield reduction of 10–80% depending on crops, type of weed flora infested, and magnitude of crop-weed competition [3]. Generally, yield loss due to weeds is 37% in developing
