title: Colony pace: a life-history trait affecting social insect epidemiology.
abstract: Among colonies of social insects, the worker turnover rate (colony 'pace') typically shows considerable variation. This has epidemiological consequences for parasites, because in 'fast-paced' colonies, with short-lived workers, the time of parasite residence in a given host will be reduced, and further transmission may thus get less likely. Here, we test this idea and ask whether pace is a life-history strategy against infectious parasites. We infected bumblebees (Bombus terrestris) with the infectious gut parasite Crithidia bombi, and experimentally manipulated birth and death rates to mimic slow and fast pace. We found that fewer workers and, importantly, fewer last-generation workers that are responsible for rearing sexuals were infected in colonies with faster pace. This translates into increased fitness in fast-paced colonies, as daughter queens exposed to fewer infected workers in the nest are less likely to become infected themselves, and have a higher chance of founding their own colonies in the next year. High worker turnover rate can thus act as a strategy of defence against a spreading infection in social insect colonies.
authors.affiliation: Institute of Integrative Biology (IBZ), ETH Zürich, ETH Zentrum CHN Universitätsstrasse 16, Zürich 8092, Switzerland severine.buechel@zoologi.su.se.
authors.forename: Séverine Denise
authors.initials: SD
authors.lastname: Buechel
authors.affiliation: Institute of Integrative Biology (IBZ), ETH Zürich, ETH Zentrum CHN Universitätsstrasse 16, Zürich 8092, Switzerland.
authors.forename: Paul
authors.initials: P
authors.lastname: Schmid-Hempel
mesh_terms: D000818:Animals; D001516:Bees / Q000469:parasitology* / Q000502:physiology; D003421:Crithidia / Q000235:genetics / Q000502:physiology; D005838:Genotype; D006790:Host-Parasite Interactions; D008018:Life Cycle Stages; D013045:Species Specificity; D013997:Time Factors
keywords: Bombus; host–parasite interaction; life history; non-immunological defence; social insects; worker longevity