Life-stage and sex influencePhilornisectoparasitism in a Neotropical woodpecker (Melanerpes striatus) with essential male parental care

Abstract

The nestlings of many Neotropical bird species suffer from Philornis (Diptera: Muscidae) ectoparasitism. While nestlings are typically considered the intended targets, recent work indicates that Philornis infest adult birds more frequently than previously appreciated, yet few studies have concurrently surveyed nestlings and adults for Philornis in the same population. Over six field seasons (2012 to 2017), I documented the presence of current or recent subcutaneous Philornis infestations on adult and nestling Hispaniolan Woodpeckers (Melanerpes striatus) from the same population. I tested the following three non-mutually exclusive hypotheses regarding occurrence of Philornis on adult birds: (1) nestlings are more vulnerable to Philornis parasitism than adults, (2) nesting is associated with Philornis parasitism in adults, and (3) Philornis parasitism is associated with incubation and brooding investment. While nestling and adult woodpeckers exhibited similar prevalence of parasitism, parasitized nestlings hosted on average 3.5 times more Philornis wounds (larvae plus scars) than parasitized adults. Nesting per se was not significantly associated with parasitism among adults, as breeding and non-breeding adults showed similar prevalence and intensity. However, adult males, which perform overnight incubation and brooding, were significantly more likely to be parasitized than adult females. This last result supports the hypothesis that incubation and brooding investment increase the risk of Philornis parasitism for adults, but this conclusion is complicated by the lack of an association between parasitism and nesting status. Together, these results raise questions about the degree of host life-stage specialization and whether adult parasitism is incidental or part of an alternative parasitic strategy for Philornis.

Life‐stage and sex influence Philornis ectoparasitism in a Neotropical woodpecker Melanerpes striatus with essential male parental care

“…The data that support the findings of this study are openly available in the repository OSF.IO at this link: https://doi.org/10.17605/OSF.IO/UNKSW (LaPergola 2023). The registration at OSF.IO can also be viewed here: https://doi.org/10.17605/OSF.IO/HGU5Q.…”

Mortality of an adult Antillean Palm Swift (<em>Tachornis phoenicobia</em>) associated with <em>Philornis</em> sp. parasitism in the Sierra De Bahoruco, Dominican Republic

“…Philornis typically targets nestlings, where the static environment would conceivably be more conducive for locating and infecting hosts. Although records of Philornis larva infesting adult birds are increasingly recognized and reported (Quiroga et al 2020, LaPergola 2021, evidence thus far supports the hypothesis that adult infestation is incidental. For example, in the comparatively less aerial Hispaniolan Woodpecker, Philornis parasites were only slightly more likely to occur on nestlings than on adult birds, but the parasite loads of nestlings were ~3.5 times greater on average than those of adult woodpeckers (LaPergola 2021).…”

“…The aerial foraging habits of swifts might make Philornis targeting adults less feasible and less successful as a strategy. The most likely route to infestation would be when an adult remains in contact with an infested nest for a prolonged period of time, such as during incubation or brooding (Quiroga et al 2020, LaPergola 2021. The incubation behavior of ANPS is unknown, but in at least some swift species, both parents incubate and brood young (Steeves et al 2020, Gunn et al 2021, so the specimen here might have been infested while brooding or roosting with young.…”