Feeding of adult Ornithodoros tartakovskyi ticks using a modified artificial membrane feeding system.

Development and maintenance of laboratory tick colonies provides reliable access to a variety of tick species at multiple life stages. Advances in techniques for the membrane feeding of ticks reduce the number of laboratory animals needed for colony maintenance. In the present study, modifications to the existing protocol for in vitro feeding of the argasid species Ornithodoros tartakovskyi were made. Adult O. tartakovskyi ticks of both sexes were allowed to feed to engorgement using a novel membrane feeding apparatus in a six-well plate format with well-inserts of laboratory-grade, wax sealing film. Of the 193 ticks placed on the membrane, 89% (n = 172) fed until engorgement and subsequently detached. The modified feeding method described will aid in future laboratory tick-based research because it allows for increased containment, ease of sorting, successful in vitro feeding, easy replacement of blood meals and a reduction in the total volume of blood meal required.

Nocturnal and diurnal rhythms in the unstriped Nile rat, Arvicanthis niloticus.

In a laboratory population of unstriped Nile grass rats, Arvicanthis niloticus, individuals with two distinctly different patterns of wheel-running exist. One is diurnal and the other is relatively nocturnal. In the first experiment, the authors found that these patterns are strongly influenced by parentage and by sex. Specifically, offspring of two nocturnal parents were significantly more likely to express a nocturnal pattern of wheel-running than were offspring of diurnal parents, and more females than males were nocturnal. In the second experiment, the authors found that diurnal and nocturnal wheel-runners were indistinguishable with respect to the timing of postpartum mating, which always occurred in the hours before lights-on. Here they also found that both juvenile and adult A. niloticus exhibited diurnal patterns of general activity when housed without a wheel, even if they exhibited nocturnal activity when housed with a wheel. In the third experiment, the authors discovered that adult female A. niloticus with nocturnal patterns of wheel-running were also nocturnal with respect to general activity and core body temperature when a running wheel was available, but they were diurnal when the running wheel was removed. Finally, a field study revealed that all A. niloticus were almost exclusively diurnal in their natural habitat. Together these results suggest that individuals of this species are fundamentally diurnal but that access to a running wheel shifts some individuals to a nocturnal pattern.