Population dynamics of ticks on indigenous cattle in a pastoral dry to semi-arid rangeland zone of Uganda

Studies on seasonality and population dynamics of ticks on indigenous cattl e and their crosses (calves) were carried out in Buruli Ranching Scheme, Na biswera, Luwero district of Uganda on three treatment groups of animals: gr oup 1 (twice a week dipping), group 2 (once a month dipping) and group 3 (n o tick control). During this study, four major species of ticks of economic importance were recorded in decreasing order of abundance: Rhipicephalus a ppendiculatus, Rhipicephalus evertsi evertsi, Amblyomma variegatum and Boop hilus decoloratus. Of these ticks, a seasonal pattern of activity was only observed in R. appendiculatus ticks, with peak activities occurring during rainy seasons. Greater numbers of ticks were recorded on cows than calves i n the three treatment groups, with the exception of A. variegatum where the reverse occurred. The mean numbers of ticks per animal were highly signifi cantly different (p < 0.01) when group I animals were compared with group 2 and 3 animals. However, no significant differences (p > 0.05) were observe d in mean tick numbers between group 2 and 3 animals. Highly significant di fferences (p < 0.01) were observed in mean tick numbers on cows and calves (more than 12 months old) in different calving seasons. The state of lactat ion only affected tick counts on cows in group 1; significantly more ticks (p < 0.01) were observed in lactating than nonlactating cows. Furthermore, significantly greater (p < 0.05) numbers of ticks (with the exception of B. decoloratus) were recorded during the second year of study (March 1992-May 1993) than the first year (January 1991-February 1992), despite lower rain fall during the former period. Exp App; Acarol 23: 79-88 (C) 1999 Kluwer Ac ademic Publishers.