In herbivorous insects, the degree of host specialisation may be one ecological factor that shapes
lifespan. Because host specialists can only exploit a limited number of plants, their lifecycle should be
synchronised with host phenology to allow reproduction when suitable hosts are available. For species
not undergoing diapause or dormancy, one strategy to achieve this could be evolving long lifespans.
From a physiological perspective, oxidative stress could explain how lifespan is related to degree of host
specialisation. Oxidative stress caused by Reactive Oxygen Species (ROS) might help underpin ageing
(the Free Radical Theory of Aging (FRTA)) and mediate differences in lifespan. Here, we investigated
how lifespan is shaped by the degree of host specialisation, phylogeny, oxidative damage accumulation
and antioxidant protection in eight species of true fruit flies (Diptera: Tephritidae). We found that
lifespan was not constrained by species relatedness or oxidative damage (arguing against the FRTA);
nevertheless, average lifespan was positively associated with antioxidant protection. There was no
lifespan difference between generalist and specialist species, but most of the tephritids studied had
long lifespans in comparison with other dipterans. Long lifespan may be a trait under selection in fruitfeeding
insects that do not use diapause.