An experimental evaluation of conventional control measures against the sheep tick,Ixodes ricinus(L.) (Acari: Ixodidae). I. A unimodal seasonal activity pattern

Abstract Questing individuals ofIxodes ricinus(L.) on a naturally infested moorland in Wales were censused every fortnight from January 1981 to October 1982 by blanket-dragging, and feeding ticks were counted on the sheep hosts. The seasonal activity patterns for ticks in all three stages were unimodal, with nymphs and adults active between March and July, and larvae active between April and August. This unimodal, as opposed to the usually described bimodal, pattern is explained in terms of the long cold winters and short summers of this field site. The survival time of questing nymphs was calculated from an analysis of their changing lipid content during the activity season to be a maximum of four months, which is consistent with the other field observations. The precise identification of the pattern of activity, as well as being essential for the application of appropriately timed control procedures, is necessary for the interpretation of the tick-host interactions under various control regimes that were applied.