A preliminary investigation into resistance to synthetic pyrethroids by the sheep biting louse (Bovicola ovis) in New Zealand

Abstract

Increasing reports of failure of synthetic pyrethroids for the control of Bovicola ovis on sheep lead to a preliminary investigation into the insecticide resistance status of this pest during 1994. Eighteen strains of lice from North and South Island flocks experiencing failure of synthetic pyrethroid treatments to control lice were exposed to cypermethrin (high-cis) in a treated surface (contact) bioassay. Lice from a group of hermit sheep were chosen as a reference susceptible strain against which resistance of field strains was measured and resistance factors (RFs) calculated. Low to moderate resistance to cypermethrin (high-cis) was demonstrated, with RFs ranging from 1.0 to 12.4.

Navigating the resistance: Current perspectives on ectoparasite control in veterinary medicine

“…According to the conducted studies, the prolonged usage of ectoparasites of the same class over an extended period of time is a risk factor for the emergence of ectoparasitic resistance in Australia (Levot et al, 1995;Wilson et al 1997;Jonsson et al, 2000). It can also be an issue when identical products are used to control various ectoparasites and the epidemiology of different types of infestations, such as resistance in external parasites when macrocyclic lactone anthelmintics are used (FAO, 2004).…”