Just phoresy? Reduced lifespan in red palm weevils Rhynchophorusferrugineus (Coleoptera: Curculionidae) infested by the miteCentrouropoda almerodai (Uroactiniinae: Uropodina)

Invasive species usually act as carriers of their associated organisms like parasites and symbionts. This phenomenon has also occurred with the recent colonization of the red palm weevil, Rhynchophorus ferrugineus, in the Mediterranean area: this introduced pest is strictly associated with several species of mites (mainly belonging to the suborder Uropodina). In this paper, we document the high rate of infestation of Central and Southern Italian red palm weevil populations by the mite Centrouropoda almerodai. This mite species was found in all five investigated regions and infested the large majority of individuals (from 57 to 95%) by settling preferentially under the first pair of wings. Although this mite–weevil association is usually considered as a phoretic relationship, i.e. without impact on hosts, our study revealed that infested individuals have a significantly reduced lifespan (by one-third) in comparison with those not infested. Our study provides evidences that C. almerodai imposes a cost on its carrier host, at least under laboratory conditions, leading us to believe that the R. ferrugineus– C. almerodai relationship is also not phoretic in the wild.