Unexpected seasonal variation in offspring size and performance in a viviparous ectoparasite.
Offspring size and performance in invertebrates often decrease with maternal age or as a response to seasonal environment. In viviparous ectoparasites maternal provision may wholly determine offspring performance outside the host. The viviparous deer ked (Lipoptena cervi), an ectoparasite of cervids, breeds from autumn to spring. We reared deer ked pupae through the reproductive period to investigate whether offspring size and performance vary according to maternal age and offspring environment. We expected that, in autumn, young females would produce the largest offspring to ensure that early-born pupae would survive a long period of winter diapause, and that offspring size would decrease with maternal age and decreasing diapause length. Diapause was associated with a significant weight loss, which reduced survival through post-diapause development. It was thus surprising that the early-born offspring were the smallest, and that size and survival (eventually) increased towards the spring. The variability among offspring in the length of off-host period seems to be an important component of life-history evolution in this ectoparasite, and should be studied further. Unexpected seasonal variation in the offspring size of this blood-feeding ectoparasite may result from changes in female resources due to weakening host condition as the winter progresses.
Department of Biology, University of Oulu, FI-90014 Oulu, Finland. laura.harkonen@oulu.fi
Laura
L
Härkönen
Eija
E
Hurme
Arja
A
Kaitala
D000818:Animals; D049628:Body Size / Q000502:physiology*; D003670:Deer; D004175:Diptera / Q000033:anatomy & histology / Q000502:physiology*; D004478:Ectoparasitic Infestations / Q000469:parasitology; D004777:Environment; D016014:Linear Models; D008423:Maternal Age; D012621:Seasons; D016019:Survival Analysis; D013997:Time Factors