18TOMAS

Current knowledge on the mechanisms underlying host searching and detection is incomplete for many ectoparasitic taxa. Recently, a novel hypothesis has been formally postulated suggesting that ectoparasites may eavesdrop on host acoustic signals as cues for host detection. The main body of the postulated hypothesis has been formulated for ectoparasites eavesdropping on nestling begging signals, but it has been extended to comprise other host groups apart from birds that display begging behaviours, and also other acoustic signals apart from begging signals. The possible use of acoustic cues for host detection by ectoparasites has scarcely been investigated, yet it may greatly enhance our understanding on the evolution of signals. It may aid comprehension of the reliability of signals of need and parent-offspring communication systems, and also of sexual selection processes.. However, there are well-known examples of interspecific eavesdropping on host auditory signals by parasites that include parasitoid flies attracted to calling crickets and cicadas, and frog-biting midges and mosquitoes attracted to frog calls. Some anecdotal evidence even suggests that ectoparasites are able to detect and orient towards bird song and calls. Therefore, this proposal aims to investigate the potential use of host acoustic signals by ectoparasites as cues for host location. The hypothesis will be tested with an array of ectoparasite-host assemblages, including diverse groups of ectoparasitic insects and avian hosts, and in different contexts. We aim to produce meaningful generalizations of the idea to explain the evolution of host detection mechanisms by parasites in particular and animal communication networks in general. Thus, we will explore whether ectoparasites are attracted by nestling begging calls in the field and in the laboratory. We will also determine whether ectoparasites use nestling begging calls to synchronize their emergence with the appropriate nesting stage. Moreover, we will analyze whether ectoparasite load is related to begging intensity among bird species. We will also test the hypothesis that ectoparasites can detect avian hosts by eavesdropping on bird calls and song by means of field and laboratory approaches, and exploring whether characteristics of song are related with ectoparasite load among bird species. Results attained by this project will greatly improve fundamental and applied knowledge on host-parasite interactions, wildlife management and disease transmission processes. Confirmation of this hypothesis may have profound implications for animal and human welfare, because ectoparasites are involved in transmitting some of the most deadly and economically relevant diseases regarding livestock industry and human health. The novelty and interest of this proposal will result in a large number of publications that will be published in the most relevant journals of the areas of Ecology and Evolution. This proposal guarantees excellent results which will place Spain on top of research on host-parasite interactions, fulfilling this requirement of the Spanish Strategy of Science, Technology and Innovation.