Modulation of immune responses of Rhynchophorus ferrugineus (Insecta: Coleoptera) induced byudthe entomopathogenic nematode Steinernema carpocapsae (Nematoda: Rhabditida).

摘要

Aim of this study was to investigate relationships between the red palm weevil (RPW)udRhynchophorus ferrugineus (Olivier) and the entomopathogenic nematode Steinernema carpocapsaeud(EPN); particularly, the work was focused on the immune response of the insect host in naive larvae andudafter infection with the EPN. Two main immunological processes have been addressed: the activity andudmodulation of host prophenoloxidase-phenoloxidase (proPO) system, involved in melanization of not-selfudand hemocytes recognition processes responsible for not-self encapsulation. Moreover, immune depressiveudand immune evasive strategies of the parasite have been investigated. Our results suggest that RPWudpossess an efficient immune system, however in the early phase of infection, S. carpocapsae induces audstrong inhibition of the host proPO system. In addition, host cell-mediated mechanisms of encapsulation,udare completely avoided by the parasite, the elusive strategies of S. carpocapsae seem to be related to theudstructure of its body-surface, since induced alterations of the parasite cuticle resulted in the loss of its mimetic properties. S. carpocapsae before the release of its symbiotic bacteria, depress and elude RPWudimmune defenses, with the aim to arrange a favorable environment for its bacteria responsible of theudsepticemic death of the insect target.