Effects of Pyrethroids on Respiration in the Twospotted Spider Mite (Acari: Tetranychidae)

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Abstract
The influence of eight pyrethroids on Tetranychus urticae Koch respiration and mortality was examined. The more potent pyrethroids caused a more rapid rate of oxygen consumption initially, compared to controls. However, at 72h the compounds correlated with the highest oxygen consumption at 0 h were correlated with the lowest rate of oxygen consumption compared to controls. This phenomenon was reflected in the slopes of the respiration curves versus time. The potency rank for the pyrethroids as determined by respiration was FMC-54800 [1,1′-biphenyl-3ylmethyl-cis-3-(2-chloro-3,3,3-trifluoropropenyl)-2,2-dimethylcyclopropanecarboxylate] > fenpropathrin > fluvalinate > flucythrinate > cypermethrin > fenvalerate > permethrin > deltamethrin, whereas the potency ranking using the FAO slide-dip technique to measure mortality was FMC-54800 > cypermethrin > fluvalinate > fenvalerate > fenpropathrin > deltamethrin > permethrin > flucythrinate. Thus, the potency rankings as determined by respiration and mortality were similar, with the exception of flucythrinate and fenpropathrin, which were much more effective by the criterion of respiration. These results demonstrated that pyrethroids can affect respiration in the twospotted spider mite; however, the ability of pyrethroids to affect respiration is not strictly correlated with their potency as determined by mortality in slide-dip studies. A relationship between pyrethroid-stimulated respiration and mite outbreaks is suggested.