THE PYRETHRINS AND RELATED-COMPOUNDS .41. STRUCTURE-ACTIVITY-RELATIONSHIPS IN NONESTER PYRETHROIDS AGAINST RESISTANT STRAINS OF HOUSEFLY (MUSCA-DOMESTICA L)

A series of pyrethroids, related to NRDC 200 and etofenprox (MTI500) i n which the central region is represented by a non-ester link, have be en tested against one susceptible and two resistant strains (kdr and s uper-kdr) of houseflies (Musca domestica L.). A range of structural va riations 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 n o correlation of resistance with structural features was detectable fo r this region. Other changes examined were the substituent on the phen yl ring in the 'acid' component and the bridging group in the 'alcohol ' component where small variations in response were observed. Examinat ion of the effect of varying the 'alcohol' side chain was limited by l ack of active analogues.