[Population dynamics of Rhipicephalus pusillus Gil Collado, 1938 (Acarina, Ixodidae) in 1986-1987 in south-eastern Spain: modelling of the biological cycle].

The evolution of the Rhipicephalus pusillus population, a parasite of the european wild rabbit, Oryctolagus cuniculus, is studied in a locality of the Province of Granada (Spain), in 1986-1987. The moving average technique was applied to the sampling data (358 hosts), for each stage of the postembryonic cycle. This technique permitted us, together with the habitual usage of the statistics, to understand in a more complete manner, the evolution of daily changes which affect the average number of ticks over the population of the host rabbits. Various factors allowed us to envisage a strong dependency of the parasitism of the females and the larvae in relation with the developing environmental conditions, which determine the apparition and concentration of the parasites on the hosts. A very strong correlation between the parasitism by male ticks and that of the female ticks was observed for the two year duration of our investigation. However, the moment at which the distribution of the ectoparasites is contagious, the male abundance is nearly twice that of the females. The larvae respond to a similar pattern of distribution both years, but it is necessary to note a delay, which we can attribute to climatic changes registered from one year to the next. The nymphs, on the other hand, present a different distribution curve for each year. Their presence depends on climatic conditions and especially that of the situation of the ticks and hosts population in the moments proceeding: these conditions determine a deplacement of their apparition in one sense or another.