Ecological observations on the cattle tick, Boophilus microplus (Canestrini)

Studies were undertaken during 1948-1950 on Boophilus microplus under field conditions in southern Queensland to determine the duration of the non-parasitic stages, and to relate this information to tick incidence on cattle. In the area where the observations were made, the population of ticks on cattle is high in summer and autumn and low in minter and spring. Each week throughout the investigation engorged female ticks, freshly fallen from cattle, were placed in a pasture plot and their subsequent history recorded. Concurrently, observations were made on the changes in tick population on a dairy herd on an adjacent farm. Female ticks exposed on the plot between April and July produced virtually no progeny, and it is probable that the ticks in the pasture traversed by the dairy cattle exhibited a similar, though less severe, inhibition of reproduction. This failure to reproduce, combined with the dying out of larvae and protracted developmental periods of eggs, reduced to very low levels the larval population available to infest cattle during the months of August–October. Ticks exposed from late July to the following autumn produced progeny. There was a tendency for the progeny of ticks exposed in the late winter and early spring to hatch a t about the same time in the late spring, and this synchronous hatching was probably responsible for the 'spring rise' in tick population on cattle. It appears likely that the engorged female adults dropped in the early autumn represent the most important stage in the overwintering of the species in this area. Some of their larvae survive the adverse winter conditions, either in the free-living or the parasitic stage, and give rise to adults, which fall in the late winter and spring, and which in turn produce the larvae of the spring rise.