Cumulative effects of host resistance on Rhipicephalus appendiculatus Neumann (Acarina: Ixodidae) in the laboratory

Abstract

The effect of host resistance on the feeding and development of Rhipicephalus appendiculatus, the African brown ear tick, was investigated. In this 3-host species the percentages of larvae and nymphs engorging on resistant cattle, and also of those subsequently moulting, were significantly less than those of ticks feeding on susceptible rabbits (i.e. without previous tick-feeding experience). The mean weights of engorged larvae, nymphs and females were significantly reduced on resistant hosts. Fewer nymphs and females engorged, even when fed on susceptible hosts, if their previous feed had been on a resistant host, and the engorged weight was also less. If only one feed during the life-cycle was on a resistant host the final egg production was reduced by a factor of 13· 2· and l· for the larval, nymphal and adult feed respectively. The egg production of a tick population with all 3 stages feeding only on resistant hosts could be reduced by more than 98% if these effects were combined.