Meeting Abstract
We investigated how blood loss and other outcomes of hematophagous mite infestations contribute to previously reported developmental trade-offs in European starling nestlings. We first microwaved nests to reduce ectoparasites in all treatment groups one day after egg laying ceased, and assigned the nests to one of three treatments: control, blood loss and mite infestation. To simulate infestation, immediately following microwaving, we inoculated mite infestation nests with ≈ 40 Northern fowl mites. To assess treatment effectiveness on mite levels, blood spots on the eggs from nests in all treatments were assessed 10 days later. Nestling growth and survival were assessed on brood days (BD) 5, 10 and 15. On BD 5 and 10, we collected ≈10% of the blood from nestlings in the blood loss treatment and much smaller blood samples from nestlings in the other two treatments. Nestlings in all treatments were bled similarly on BD 15. From these samples we assessed blood glucose and hemoglobin concentrations, as well as hematocrit. Preliminary analyses indicate that wing length, tarsus length, body mass and blood glucose increased significantly with age, but there were no significant treatment effects. We found an interaction between treatment and age, where nestlings in the mite infestation treatment had lower levels of hematocrit and hemoglobin than other nestlings especially on BD 15. These results suggest that the effects of mite infestation extend beyond those of mere blood loss, perhaps involving a trade-off involving increased energetic demands associated with immune activation. Results will be discussed further in light of ongoing analysis of bacterial killing capacity of plasma across development, assessment of mite loads in nests after fledging, and possible seasonal influences.
