Timing of infestation influences virulence and parasite success in a dynamic multi-host–parasite interaction between the invasive parasite, Philornis downsi, and Darwin’s finches

Author(s)
Arno Cimadom, Sabine Tebbich
Abstract

Recently commenced host–parasite interactions provide an excellent opportunity to study co-evolutionary processes. Multi-host systems are especially informative because variation in virulence between hosts and temporal changes provides insight into evolutionary dynamics. However, empirical data under natural conditions are scarce. In the present study, we investigated the interaction between Darwin’s finches and the invasive fly Philornis downsi whose larvae feed on the blood of nestlings. Recently, however, the fly has changed its behavior and now also attacks incubating females. Two sympatric hosts are affected differently by the parasite and parasite load has changed over time. Our study observed a reversal of trends described two decades ago: while, currently, small tree finches (Camarhynchus parvulus) experience significantly higher parasite load than warbler finches (Certhidea olivacea), this was the opposite two decades ago. Currently, fledging success is higher in warbler finches compared to small tree finches. Our data indicate that not only intensity but also timing of infestation influences hosts’ reproductive success and parasite fitness. During incubation, prevalence was higher in warbler finches, but once chicks had hatched, prevalence was 100% in both species and parasite load was higher in small tree finches. Furthermore, our results suggest faster development and higher reproductive success of P. downsi in small tree finch nests. A change in host preference driven by larvae competition could have led to the reversal in parasite load.

Organisation(s)
Department of Behavioral and Cognitive Biology
Journal
Oecologia
Volume
195
Pages
249–259
ISSN
0029-8549
DOI
https://doi.org/10.1007/s00442-020-04807-5
Publication date
12-2020
Peer reviewed
Yes
Austrian Fields of Science 2012
106051 Behavioural biology
Keywords
ASJC Scopus subject areas
Ecology, Evolution, Behavior and Systematics
Portal url
https://ucris.univie.ac.at/portal/en/publications/timing-of-infestation-influences-virulence-and-parasite-success-in-a-dynamic-multihostparasite-interaction-between-the-invasive-parasite-philornis-downsi-and-darwins-finches(409396f3-7033-4f24-8304-5974db6d72db).html