Social parasitism and hyperparasitism in ant societies: Acoustic mimicry by the parasitoïd ichneumon eumerus in the pupal case of the butterfly phengaris alcon in red ant colonies

Details

Supervisors

Van Dyck, Hans ; Barbero, Francesca ; Sielezniew, Marcin

Faculty

Faculté des sciences

Degree label

Master [120] en biologie des organismes et écologie, à finalité approfondie

Abstract

enWithin terrestrial ecosystems, ants (Formicidae) are among the most significant contributors to biomass, abundance, and diversity. Their broad geographical distribution and eusocial organization have provided an ecological framework that has supported the evolution of numerous associations with various organisms, a phenomenon known as myrmecophily. Among the 100,000 myrmecophilous invertebrate species, approximately 10,000 of them socially parasitize ant colonies. One of the most studied examples is the butterfly Phengaris alcon. This brood parasite integrates Myrmica colonies at its larval stage primarily through chemical mimicry and further elevates its social status by mimicking the vibroacoustic emissions of queen ants. This strategy allows this parasite to access resources and services of the colony until its emergence. However, despite this special treatment, P. alcon larvae remain vulnerable to parasitism as the social parasite itself has a highly specialized parasite: Ichneumon eumerus. This parasitoïd wasp invades ant colonies to oviposit in P. alcon larvae. Once the parasitized P. alcon caterpillars pupate, I. eumerus larvae consume their host while preserving the pupal case, in which they will continue to develop for several weeks. While research has provided insights into the interaction between I. eumerus and Myrmica ants during the infiltration and exfiltration phases, less attention has been given to the interaction that occurs during the parasitoïd's developmental phase within the ant colony. In this study, we investigated whether I. eumerus also attracts ants to take care of the pupal case in which it is developing. We also examined whether I. eumerus emits vibroacoustic emissions from within the pupal case and if these signals resemble those produced by unparasitized P. alcon pupae. Finally, we assessed whether the parasitoïd's emissions play a role in the interaction with ants to enhance the parasitoïd’s survival.