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Study for Comparing the Efficiency of Certain Acaricides Against Tetranychus Urtica Koch under Laboratory and Field Conditions

A.M. Younis, S.A. Ibrahim


Three synthetic pyrethroids (biphenthrin, fluvalinate and cyhalothrin) and two recommended acaricides, a sulfur compound (propargite) and a chlorinated hydrocarbon (dicofol), were evaluated against the two spotted spider mite, Tetranychus urticae. Bioassay data of tested pesticides against susceptible and field collected adult females were compared, both did not correlate (r2= 0.074). Biphenthrin exhibited the greatest performance with both tested colony. The greatest tolerance of field population was recorded with fluvalinate and propargite. In contrast the lowest resistance ratio was calculated from cyhalothrin bioassay data. Weak correlation (r2=0.307) was estimated when field data of initial and residual efficiency were linked. Fluvalinate and propargite exhibited the worst acaricidal efficiency under laboratory conditions. Although of the uncorrelation (r2=0.036 or 0.011) between the initial or residual field activity with the bioassay data of susceptible strain, but they were moderately or strongly correlated (r2=0.69 or 0.839, respectively) with the bioassay data of field collected individuals. This study confirmed that laboratory study may not be sufficient to predict the performance of tested pesticides under field conditions.

Reprinted from Proceedings of the 1996 Beltwide Cotton Conferences pp. 1131 - 1134
©National Cotton Council, Memphis TN

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Document last modified Sunday, Dec 6 1998