Abstract
The tomato whitefly, Bemisia tabaci (Genn.) (Hemiptera: Aleyrodidae) is a worldwide pest of many crops. Organophosphorous (OP) insecticides have been used to control this insect for many years and are still being used despite the development of resistance. In this work’ evaluation of the biological activity of three organophosphorous insecticides, profenofos 72% E.C. (Selecron); chlorpyrifos 48% E.C.(Dursban) and fenitrothion 50% E.C. (Sumithion) on the felid strain of tomato whitefly was carried out on tomato plants. Whitefly adults were collected from four different Egyptian Governorates throughout three successive years (2016-2018). The LC50 value of each compound in each Governorate was used to determine the biochemical responses of this insect pest.The colorimetric test of esterase activity is a useful tool to detect the level of resistance against this group of insecticides. The obtained results showed that profenofos insecticide was more toxic on the tested insects followed by chlorpyrifos, while fenitrothion showed a low toxic effect on the tested insects in all years. The activities of α and β esterases have fluctuated up and down in some Governorates.
Highlights
Tomato whitefly ’Bemisia tabaci (Genn.) (Hemiptera: Aleyrodidae) is a small pest with a great agricultural importance worldwide (Bellows et al, 1994)
The tomato whitefly adults of both sexes were exposed to leaf discs dipped in aqueous media of the formulated tested insecticides’ profenofos 72% E.C. (Selecron); chlorpyrifos 48% E.C. (Dursban) and fenitrothion 50% E.C. (Sumithion) for ten seconds and laid flat on a thin layer of 1% agar in plastic Petri dishes
During the first year (2016) as shown in Table (2), Giza strain and Menia strain showed a high resistance index (47.50, 31.30) respectively for chlorpyrifos insecticide compared to the other strains, while Bani-Swief- strain showed moderate tolerance (RI = 7.2)
Summary
Tomato whitefly ’Bemisia tabaci (Genn.) (Hemiptera: Aleyrodidae) is a small pest with a great agricultural importance worldwide (Bellows et al, 1994). Biochemical Study: The data resulted from the biochemical assay represented changes in the activity of both esterases enzymes in different tomato whitefly strains collected from four different Egyptian Governorates during three successive years in relation to the toxicities of some OP insecticides.
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Schedule a callMore From: Egyptian Academic Journal of Biological Sciences, F. Toxicology & Pest Control
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