The free-living phase and seasonal variation of Boophilus microplus in Botucatu, São Paulo State, Brazil

Abstract

A 3-year study of the non-parasitic and parasitic phases of the cattle tick Boophilus microplus was carried out in Botucatu, São Paulo state, Brazil. Engorged females were exposed in pastures of Brachiaria decumbens at intervals of 30 days, and left in the environment protected from sun radiation and rainfall. The preoviposition and oviposition periods were influenced by climatic changes, and there was a negative correlation with the air temperature, humidity, and rainfall. Oviposition was observed throughout the year, however between the period of May to August the eggs did not hatch. The longest and shortest larval survival periods were recorded on the progeny of ticks exposed, respectively, in August and March. The seasonal variation of B. microplus was studied by the counts, at intervals of 2 weeks, of engorged females on the left side of a group of nine cross-bred cattle of both sexes and approximately two years old. Peak in tick burdens were observed in winter, while the lower levels were recorded in September and October, although this variation showed, by simple linear regressive analysis, a strong similirarity just between the first and the third cycles. There was a tendency of influence of the temperature and rainfall on the burdens on the animals.