02209nas a2200205   4500008004100000020001400041245013200055210006900187260001400256300001400270490000800284520155800292653001301850653002201863653002301885653001001908100002801918700001501946856004201961       2008                        eng d  a0031-182000aSynchronization of host-parasite cycles by means of diapause: host influence and parasite response to involuntary host shifting0 aSynchronization of hostparasite cycles by means of diapause host  cSeptember  a1343-13520 v1353 aMany parasites require synchronization of their infective phases with the appearance of susceptible host individuals and, for many species, diapause is one of the mechanisms contributing to such coincidence. A variety of ecological factors, like changes in host temperature produced by involuntary host shifting (Substitution of the usual host by an infrequent one), can modify host-parasite synchronization of diapausing ectoparasites of endothermic species. To understand the influence of host shifting on the mechanisms of parasite synchronization, we conducted experiments using the system formed by the ectoparasitic fly Carnus hemapterus and its avian hosts. We simulated the occurrence of the usual host and natural cases of host shifting by exposing overwintering carnid Pupae from Bee-eater nests (Merops apiaster) to the earlier incubation periods of two Carnus host species that frequently reoccupy Bee-eater nests. Pupae exposed to host shifting treatments advanced the mean date of emergence and produced an earlier and faster rate of emergence in comparison with Pupae exposed both to the control (absence of any host) and Bee-eater treatments. The effect was more evident for the treatment resembling the host with the most dissimilar phenology to the one of the usual host. Our results show that host temperature is an environmental cue used by this nest-dwelling haematophagous ectoparasite and reveal that Carnus hemapterus has some potential to react to involuntary host shifting by means of plasticity in the termination of diapause.10aCarnidae10aCarnus hemapterus10aon Merops apiaster10aSpain1 aCalero-Torralbo, M., A.1 aValera, F.  u<Go to ISI>://ZOOREC:ZOOR14503013830 02168nas a2200193   4500008004500000020001400045245013100059210006900190260000900259300001200268490000700280520154500287653002201832653001101854100002001865700003201885700001501917856004201932       2008                        Engldsh    a0024-406600aEctoparasite load is linked to ontogeny and cell-mediated immunity in an avian host system with pronounced hatching asynchrony0 aEctoparasite load is linked to ontogeny and cellmediated immunit  cJuly  a463-4730 v943 aSeveral contrasting hypotheses have been proposed to account for host age-biased parasite distribution, with some of them suggesting a key role of ectoparasites in the evolution and maintenance of weight hierarchies within broods. We examined parasite distribution among individual hosts across the whole period of host exposure to the parasite in a host system that shows distinct within-brood differences in age and age-related mortality. By contrast to previous hypotheses, we found that the abundance of a haematophagous, mobile ectoparasite Carnus haemapterus on nestling European rollers (Coracias garrulus) was highest approximately during the mid-nestling stage of their host, coinciding with the inflection point of the host growth phase. Parasite load increased neither with absolute resource availability (i.e. body size), nor body condition index. By contrast to previous evidence, higher parasite load under natural conditions was associated with a stronger cell-mediated immune response. However, this association was moderated by low parasite densities, as well as a better brood body condition index. Overall, although we revealed remarkable host ontogenetic effects on parasite distribution, the present study suggests that a highly mobile ectoparasite generally prefers healthier hosts. We propose that, in host systems with a marked asynchrony of hatching and background mortality within the brood, parasites favour persistence rather than nutritional attractiveness of the host. (C) 2008 The Linnean Society of London.
10aCarnus hemapterus10aEurope1 aVaclav, Radovan1 aCalero-Torralbo, Miguel, A.1 aValera, F.  u<Go to ISI>://ZOOREC:ZOOR14409054805 