A comparison of permethrin and methomyl insecticides for the control of a multiresistant strain of houseflies (Musca domestica)

Abstract A methomyl sugar bait formulation and permethrin residual spray were compared for the control of a multi‐insecticide resistant strain of housefly in a UK pig farm. The methomyl was applied as a granular scatter bait at the manufacturer's recommended rate of 25 mg m−2 active ingredient (a.i.) to the treated floor area. Permethrin was applied at 32, 64 and 128 mg m−2 a.i. to structural surfaces. The highest deposit rate of permethrin used was four times that recommended by the manufacturer for the control of flying insects. The methomyl bait gave effective control but the permethrin spray failed at all deposit rates tested. The use of permethrin increased resistance to this compound at the KD50 level from x 13 to x 560 within 10 weeks and significantly increased the proportion of flies resistant to natural pyrethrins synergised with piperonyl butoxide (P<0.01).