PHOTOSENSITIZATION PROCESSES TO CONTROL WHITEFLY (Bemesia tabaci)

Abstract

There are more than 1000 whitefly species exist in the world. The /- l t sweet potato whitefly (Bemisia tabaci) is one of the most pestiferous of the group. It attacks more than 500 species of plants from 63 plant families.

The damages caused by whitefly are weakening, and early wilting of the I ., plant, reduction of the plant growth rate and yield. It may also causes leaf

chlorosis, leaf withering, premature dropping of leaves, and plant death . • Honeydew produced by the whitefly serves as a substrate for the growth of

black sooty mold on leaves, and fruit. The mold reduces photosynthesis, and lessens the market value of the plant or yields it unmarketable. In addition to vectoring of plant viruses by this insect plant viruses transmitted by whiteflies cause over 40 diseases of vegetable, and fiber crops worldwide.

In this study we use natural, and artificial light as well as laser radiation with porphyrine. and phthalocyanine derivatives as a novel technique for control eggs, nymphs, and adults of whitefly (Bemisia tabaci) (Gennadius). Hematoporphyrine (IX), and phthalocyariine tetrasulfonate posses, several favorable features for such application as photopesticides due to: ( I) they are endowed with a high quantum yield for generation of highly cytotoxic intermediates. (2) They absorb essentially all wavelengths in the sun emission spectrum. (3) They typically act at the level of cell membranes minimizing the induction of mutagenic effects, and the onset of d photoresistance. (4) They have high photosensitizing activity towards biological systems in addition; they are already approved for medical use in photodynamic therapy of tumors and other diseases.