title: Antifungal activity in thrips soldiers suggests a dual role for this caste.
abstract: The social insect soldier is perhaps the most widely known caste, because it often exhibits spectacular weapons, such as highly enlarged jaws or reinforced appendages, which are used to defend the colony against enemies ranging in size from wasps to anteaters. We examined the function of the enlarged forelimbs of soldiers (both male and female) of the eusocial, gall-inhabiting insect Kladothrips intermedius, and discovered that they have little impact on their ability to repel the specialized invading thrips Koptothrips species. While the efficacy of the enlarged forelimb appears equivocal, we show that soldiers secrete strong antifungal compounds capable of controlling the specialized insect fungal pathogen, Cordyceps bassiana. Our data suggest that these thrips soldiers have evolved in response to selection by both macro- and micro-organisms. While it is unknown whether specialized fungal pathogens have been major selective agents in the evolution of the soldier caste in general, they were probably present when sociality first evolved and may have been the primordial enemies of social insects.
authors.affiliation: Department of Biological Sciences, Macquarie University, New South Wales 2109, Australia.
authors.forename: Christine
authors.initials: C
authors.lastname: Turnbull
authors.forename: Holly
authors.initials: H
authors.lastname: Caravan
authors.forename: Thomas
authors.initials: T
authors.lastname: Chapman
authors.forename: David
authors.initials: D
authors.lastname: Nipperess
authors.forename: Siobhan
authors.initials: S
authors.lastname: Dennison
authors.forename: Michael
authors.initials: M
authors.lastname: Schwarz
authors.forename: Andrew
authors.initials: A
authors.lastname: Beattie
mesh_terms: D000045:Acacia / Q000469:parasitology; D000818:Animals; D000935:Antifungal Agents / Q000737:chemistry*; D001522:Behavior, Animal / Q000502:physiology*; D005075:Biological Evolution; D049628:Body Size; D032661:Cordyceps / Q000502:physiology; D005260:Female; D005552:Forelimb / Q000033:anatomy & histology / Q000502:physiology; D008297:Male; D008826:Microbial Sensitivity Tests; D010941:Plant Tumors / Q000469:parasitology; D013172:Spores, Fungal / Q000187:drug effects*; D061149:Thysanoptera / Q000033:anatomy & histology / Q000737:chemistry* / Q000382:microbiology / Q000502:physiology
chemical_list: D000935:Antifungal Agents