Studies on ticks of veterinary importance in Nigeria: intrinsic factors influencing oviposition and egg-hatch of Amblyomma variegatum under natural conditions

During the peak of rains of 1983, 1984 and 1985 in the forest zone of Nigeria, female Amblyomma variegatum engorged to various weights were subjected to different experiments for the purpose of observing the intrinsic factors which influence oviposition and egg-hatch under natural conditions. Two types of oviposition patterns were observed. New terms were introduced to quantify the relationships between the daily weight loss and daily number of eggs oviposited by a tick. These terms are "actual mass", "convertible blood mass", "oviposition efficiency" and "mass conversion rate". A major advantage of adopting the "oviposition efficiency" and "mass conversion rate" is that they relate directly to the measure of the metabolic activity utilized by the tick for the process of oviposition. The entity "convertable blood mass" also enables recognition of individual capability in the utilization of blood mass for oviposition. Investigation on the relationship of weight of eggs with sequence of oviposition showed that eggs were heavier when few eggs were laid than when numerous eggs were oviposited. The heaviest eggs were laid towards the end of oviposition. Two types of relationship were found to exit between the sequence of oviposition and the eclosion period of eggs. Adult A. variegatum engorged to more than 2.49 x were affected by immersion in water for longer than 7 days. Such ticks died without ovipositing and the water in which they were submerged became dark-red. Eggs immersed in water for periods ranging from 1-7 days hatched in about the same number of days as control eggs and their viability in terms of percent-hatch was not affected.