biostudies-literatureKaech HSwiss National Science Foundatione8551https://www.ebi.ac.uk/biostudies/studies/S-EPMC8796928biostudies-literatureUnknown12(1)Endosymbiont-conferred resistance to parasitoids is common in aphids, but comes at a cost to the host in the absence of parasitoids. In black bean aphids (<i>Aphis fabae</i>), costs in terms of reduced lifespan and lifetime reproduction were demonstrated by introducing 11 isolates of the protective symbiont <i>Hamiltonella defensa</i> into previously uninfected aphid clones. Transfection of <i>H</i>.<i> defensa</i> isolates into a common genetic background allows to compare the costs of different endosymbiont isolates unconfounded by host genetic variation, but has been suggested to overestimate the realized costs of the endosymbiont in natural populations, because transfection creates new and potentially maladapted host-symbiont combinations that would be eliminated by natural selection iEcology and evolutionSimilar cost of <i>Hamiltonella defensa</i> in experimental and natural aphid-endosymbiont associations.PMC8796928CRSII3_154396Vorburger CJud SKaech HfalseSimilar cost of <i>Hamiltonella defensa</i> in experimental and natural aphid-endosymbiont associations.Endosymbiont-conferred resistance to parasitoids is common in aphids, but comes at a cost to the host in the absence of parasitoids. In black bean aphids (<i>Aphis fabae</i>), costs in terms of reduced lifespan and lifetime reproduction were demonstrated by introducing 11 isolates of the protective symbiont <i>Hamiltonella defensa</i> into previously uninfected aphid clones. Transfection of <i>H</i>.<i> defensa</i> isolates into a common genetic background allows to compare the costs of different endosymbiont isolates unconfounded by host genetic variation, but has been suggested to overestimate the realized costs of the endosymbiont in natural populations, because transfection creates new and potentially maladapted host-symbiont combinations that would be eliminated by natural selection i2022-01-01T00:00:00Z2022 Jan2026-07-09T12:14:18.47Z2026-07-09T11:15:50.084ZS-EPMC87969283512704910.1002/ece3.8551