CHAPTER ONE
1.1 Introduction
The term pesticide are the substances used to control pests. It includes herbicides (to control weeds and other plants), insecticides (to control insects), fungicides (to control fungi or other plant pathogens), nematicides (to control parasitic worms), and rodenticides (to control rodents). The term pesticide also encompasses soil fumigants, plant growth regulators, defoliants, and desiccants. Pesticides can be synthetic (developed in laboratories and manufactured) or natural.
The active chemicals used to control pests (the biologically active part of the pesticide) are called pesticide active ingredients. Pesticides are sold as mixtures of these active ingredients with inert materials used to improve safety and facilitate storage, handling, and application.
Insecticides are products that help to minimise the damage to plants, animals and human beings by controlling insectpest. From the point of view of protecting cultivated or wild growing plants, insects are the most important group of pests because they represent the most abundant animal group. Of the approximately 1.2 million known insect species, 5,000 to 10,000 are economically noxious, and their influence on reduced quantity and quality of plants depends on numerous abiotic and biotic factors.
Experts and users of insecticides are aware of the great importance of this group of plant protection products in providing sufficient quantities of food. Still, many negative examples of improper usage of insecticides from the past and present warn us about the great attention necessary when using insecticides.
The application of insecticides is often necessary in green house crop production to prevent damage from insect pests that could render the plants unsalable. However, pesticide usage can lead to toxicity issues, which may adversely affect plant growth and development. It seems plausible that applications insecticides could adversely affect photosynthesis by clogging, or at least partially blocking, plant stomates the microscopic pores in leaves through which gases (water vapor and CO2) are exchanged.
In general, plants have mechanisms inside the plant for the degradation or sequestration of most commercial pesticides, even though such chemicals are foreign to plants. Most often, these biotransformation mechanisms are independent of, and have no relation to, the mode of action and physiological lesions involved in the pesticidal activity; instead, they relate to the functional or reactive groups or linkages in the compound which are susceptible to enzymatic or chemical attack (Casida and Lykken, 1969).
1.2 Statement of Problem
The practice of using plant derivatives, or botanical insecticides as we now know them, in agriculture dates back at least two millennia in ancient China, Egypt, Greece, and India (Thacker, 2002). Dramatically predating discoveries of the major classes of synthetic insecticides has shown that overzealous use of synthetic insecticides led to numerous problems unforeseen at the time of their introduction: acute and chronic poisoning of applicators, farm workers, and even consumers; destruction of fish, birds, and other wildlife; disruption of natural biological control and pollination; extensive groundwater contamination, potentially threatening human and environmental health; and the evolution brands of commercial insecticide on plant growth.
