Contents - Faperta

12 Biotechnological Approaches for Pest Management and Ecological Sustainability
use of growth-regulating substances that hamper the development of various stages of
insects. Efforts should continue to search and identify newer compounds that can be used
successfully in pest control programs.
Pest Resurgence
Resurgence of cotton whitefl y, B. tabaci, has been reported from several crops as a result
of overuse of synthetic pyrethroids. Resurgence of aphid, A. gossypii, and leafhopper, A.
biguttula biguttula, in cotton, brown planthopper, Nilaparvata lugens (Stal), in rice, and mites,
Tetranychus, in vegetables and apple have also been reported (Heinrichs and Mochida,
1984; Hoffmann and Frodsham, 1993; Hardin et al., 1995). Some of the major factors causing
pest resurgence are:
• Application of high doses of nitrogenous fertilizers.
• Use of sublethal doses of insecticides.
• Reduction in population of natural enemies due to broad-spectrum pesticides.
• Favorable conditions for insect multiplication.
This problem not only leads to increased use of pesticides, but also increases the cost of
cultivation, greater exposure of the operators to toxic chemicals, and failure of the crop in
the event of poor control of the target insect pests.
Pesticide Residues in Food and Food Products
Pesticide residues fi nd their way to human beings through consumption of commodities
contaminated with pesticides. Many scientifi c studies have proved biomagnifi cation of
pesticide residues in human tissues, and products of animal origin. Chlorinated insecticides
are more persistent in nature compared to organophosphates, carbamates, and synthetic
pyrethroids. In order to regulate pesticide residues to safe levels, the Food and Agriculture
Organization (FAO) and World Health Organization (WHO) have prescribed pesticide
residue tolerance limits for agricultural commodities for 50 pesticides. Over 100,000 cases
of accidental exposure to pesticides are reported every year, of which a large number are
fatal. Pesticides are composed of active ingredients and inert material. The inert substances
at times may be more toxic than the active ingredient. Some of the inert ingredients have
been suspected to be carcinogenic, while others have been linked to disorders of the central
nervous system, liver, and kidney, as well as birth defects and acute toxicity. All pesticides
are designed to kill insect pests, but can also kill human beings and other nontarget
organisms if ingested in suffi cient amounts. A natural mix of pesticides and fertilizers can
signifi cantly affect the immune and neuroendocrine systems.
Contamination of Soil and Water
Most of the pesticides applied for pest control ultimately fi nd their way into soil and water.
It has been estimated that nearly 50% of the pesticides applied to crop foliage reach the soil
either as spray drift or as runoff. Pesticide residues in soil fi nd their way into the aquatic
system or may accumulate in plants. Most lawn care chemicals have been associated with
the death of birds. Fish in rivers and streams have often been found to contain residues of
more than one pesticide. Pesticides are also responsible for a decline in the number of