A Survey of Organophosphate Susceptibility in Populations of Bovicola ovis (Schrank) (Phthiraptera: Trichodectidae)

Abstract

A toxicological survey of 28 field populations of the sheep body louse, Bovicola ovis, identified only one strain whose response to diazinon was recognisably separate from the normally distributed responses of the other strains. the resistance factor (at LC50) of this strain was about 9 times. Resistance to diazinon correlated positively with resistance to coumaphos, but not to propetamphos. the lack of correlation between strain resistances to diazinon and cypermethrin indicates that organophosphate chemicals can be recommended to woolgrowers whose flocks are infested by pyrethroid‐resistant lice. Conversely, the results presented here suggest that, at least for the diazinon‐resistant strain, a pyrethroid or propetamphos treatment would be the most appropriate control option. Copyright © 1994, Wiley Blackwell. All rights reserved