Studies on the survival of the non-parasitic stages of the cattle tick Boophilus microplus in three climatically dissimilar districts of North Queensland

Abstract

Survival of the non-parasitic stages of the cattle tick, Boophilus microplus (Canestrini), has been investigated over a period of 5 years in 25, 40, and 80 in. rainfall districts of north Queensland. Engorged ticks were exposed regularly in field plots and in Stevenson screens, and the times of egg hatchmg (prehatch period) and periods of survival of the larvae were observed. The prehatch period in the three districts followed the same pattern and was related to seasonal temperature changes, varying from less than 4 weeks in midsummer to over 13 weeks in midwinter. A relationship between minimum prehatch period and mean air temperature for ticks exposed in screens was established, but the data from ticks exposed in the field were too variable to establish a relationship between prehatch periods and soil temperatures. Hatching was recorded in every month of the year from all districts, but during the driest months in the 25 in. rainfall areas many ticks in exposed situations failed to reproduce. Larval survival and total longevity also followed a similar pattern in all districts. The longest survival periods were recorded for the progeny of ticks exposed late in the wet season from March to April, and the shortest survival periods for the progeny of ticks exposed during the dry season from August to September. Mean maximum total longevity for ticks exposed in field plots in the 25 in. rainfall district varied from 10 to 22 weeks, in the 40 in. rainfall district from 14 to 22 weeks, and in the 80 in. rainfall district from 15 to 26 weeks. The data on prehatch and survival periods are a suitable basis for formulating recommendations for tick control by pasture spelling and planned dipping.