The pyrethrins and related compounds. Part XLI. Structure-activity relationships in non-ester pyrethroids against resistant strains of housefly (Musca domestica L.)

A series of pyrethroids, related to NRDC 200 and etofenprox (MTI500) in which the central region is represented by a non-ester link, have been tested against one susceptible and two resistant strains (kdr and super-kdr) of houseflies (Musca domestica L.). A range of structural variations in the central region have been examined. Resistance factors mostly fell within narrow ranges for both resistant strains i.e. 10-50-fold resistance against kdr and 50-150-fold against super-kdr; thus no correlation of resistance with structural features was detectable for this region. Other changes examined were the substituent on the phenyl ring in the 'acid' component and the bridging group in the 'alcohol' component where small variations in response were observed. Examination of the effect of varying the 'alcohol' side chain was limited by lack of active analogues.