Obligate endosymbionts limit thermal tolerance of host species: Buchnera and aphids

The thermal tolerance of an organism limits its ecological and geographic range and ispotentially affected by dependence on temperature-sensitive symbiotic partners. Aphidspecies vary widely in heat sensitivity, but almost all aphids are dependent on the nutrient-provisioning intracellular bacterium Buchnera, which has a reduced genome potentially limiting heat tolerance. We addressed whether heat sensitivity of Buchnera underlies variation in thermal tolerance among five aphid species. We measured how heat exposure of juvenile aphids affects later survival, maturation time, and fecundity.