Development of ixodid ticks under natural conditions in Nigeria.

The developmental periods of five tick species were recorded from egg to adult stages under natural conditions. The ticks were Amblyomma variegatum, Boophilus decoloratus, B. geigyi, Hyalomma rufipes and H. truncatum and the natural condition was a grazing field on which "open" site and "shade" were recognised. The investigation took place between April 1980 and March 1981. The hatching patterns of larvae, attachment, engorgement, larvo-nymphal and nympho-adult moulting periods and the survival of larvae and nymphs during different climatic periods of the year were recorded. While the attachment and engorgement periods which were recorded on the animal were relatively constant for each tick species throughout the period of investigation the hatching patterns and moulting periods were influenced by rainfall and temperature. The moulting periods of larvae and nymphs kept in the open as well as the total duration of the life cycle were lower than those of ticks kept in the shade. The survival of larvae and nymphs of all tick species was lowest during the peak of rains and highest during the dry season; the survival was also generally higher among larvae and nymphs kept in the shade than those kept in the open. The results were related to the distribution pattern and seasonal occurrence of some of the tick species in Nigeria.