Influence of environmental factors on oviposition and egg development in Amblyomma limbatum and Aponomma hydrosauri (Acari: Ixodidae).

This study examined the influence of temperature and light on the length of the pre-oviposition period of engorged females of two Australian ixodid ticks, Amblyomma limbatum and Aponomma hydrosauri. The hatching success and development time of eggs of both species were also compared at different temperatures and relative humidities. Darkness was found to have no effect on the duration of the pre-oviposition time or reproductive output of females of either species. In contrast, the preoviposition period of females of both species decreased with increasing temperature. Amb. limbatum females had shorter pre-oviposition periods than Ap. hydrosauri at all temperatures examined. Temperature and relative humidity had a marked effect on the hatching success of eggs. Eggs of both species had reduced hatching success at low relative humidities. Eggs failed to hatch at temperatures below 21 degrees C. Ap. hydrosauri eggs also failed to hatch at 34 degrees C while Amb. limbatum eggs failed to hatch at 36 degrees C. Within the range of temperatures suitable for egg development, the hatching times of eggs of both species decreased with increasing temperature. Amb. limbatum eggs developed faster than Ap. hydrosauri eggs at temperatures greater than 25 degrees C, but slower at cooler temperatures. These differences in the duration of their preoviposition period, and the responses of females and their eggs to different temperatures and relative humidities correlate with the different climates the two species experience throughout most of their distributional range.