الفهرس 
REVIEW OF LITERATUREOnly 14 pages are availabe for public view
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Abstract
Pesticides provide innumerable benefits for the control of various pests which destroy almost 33% of food crops. Thus, pesticides in different formulations can be applied to control pests and diseases. Although there has been a move toward an integrated pest management approach; the uses of pesticides as chemical control agent remain the cornerstone in the pests management (Norris et al., 2003). However, the use of such agents has also resulted in significant cost to public health and environment.
The toxicity of a chemical can be affected by the formulation (Pereira et al., 2009) and the presence of a biotic or biotic factors. The efficacy of pesticides is also affected by the additives to the pesticides formulations. The commercial formulation of a pesticide includes technical-grade active ingredient as well as “other” ingredients, which are considered as trade secret and is not a public knowledge. There are known cases where the “other” ingredients in the commercial formulations are more toxic than the technical-grade active ingredient (Mann and Bidwell, 1999; Kitulagodage et al., 2008).
Most pesticides are formulated with solvents, wetting agents and other materials which increase the opportunity of the pesticide to be in contact with the pest. Formulating agents are selected on the basis of their chemical, physical, and toxicological properties so as to achieve maximum pest control with minimal toxicity to other organisms. Careful toxicological studies are made on the pesticide before and immediately after formulation.
Pesticide formulators are concerned with development of physically and chemically stable pesticide compositions which can be applied uniformly by the user and which result in effective and efficient pest control. Although the improved efficacy of the more recent pesticides has allowed a reduction in uses as low as a few grams ( or ml) per hectare, the capability to effectively deliver these smaller amounts of agrichemicals to specific targets has become increasingly difficult to achieve (Hall, 1985).
Surfactants play a major role in pesticide in both formulation and optimization of biological efficiency. Surfactants are essential for preparations of any disperse system, such as oil/water emulsion, suspension concentrate and micro emulsion. Surfactants are also essential for maintaining the long-term physical stability of these systems and their application as sprays. The surfactants play an important role in the formulations; where they enhance and optimize the biological efficiency of agrochemicals (Siyunan and Garvin, 1994). The surfactants used in formulation can improve the characteristics of the spray solution by acting as a utility modifier, such as compatibility agent and a spray modifier, such as spreader. Surfactants also enhance pesticides activity through increasing the pesticide foliar penetration ( Mortize and Martin, 1993). Surfactants improve the chemical and physical properties of the spray preparation. Surfactants may increase solubility of the active ingredient in the spray solution. They may also affect spray retention, droplet spreading, and drying rates, as well as properties of the deposit of the chemical formed on droplet drying, i.e deposit from and interface area, hygroscopic properties and possibly distribution of the active ingredient within the deposit (Daniel and James, 1967).
Surface active agents (surfactants) are agents that reduce the surface tension and increase the wetting power of water; soaps or detergents have these properties. The
emulsifying agents (emulsifiers), wetting agents or wetters, dispersing agents or dispersants, foaming agents and spreading agents all these are belonging to the group of surface active agents. A solution of surface-active agents in water differs from pure water in several ways. It firstly lowers the surface tension, enhances wetting power and dispersing properties (Jamba, 2008). Reduction of surface tension and improvement of wetting power both play an important role while spraying chemicals. They have a profound influence on the size of the spray droplets and on the spreading, retention and run-off of the spray liquid on the target surface.
The present study was carried out to improve certain properties of different pesticides formulations and to determine their physico-chemical properties. The evaluation of their pesticidal efficiency and persistence in the field was also investigated against different pests.