E se il punteruolo affamasse Steinernema carpocapsae?

Abstract

Rhynchophorus ferrugineus (Olivier 1790) (Coleoptera: Curculionidae), phytophagus of palms, has been used as a model to deepen the knowledge of the host-entomopathogen relationship. The effects of Steinernema carpocapsae (Nematoda: Steinernematidae) on the growth and immunoactivity of R. ferrugineus larvae were compared with another model insect Galleria mellonella L. (Lepidoptera: Pyralidae). Although S. carpocapsae had a negative effect on the weight and mortality of R. ferrugineus, it was not able to replicate in the hemolymph with the same rates found for the moth. In vivo and in vitro effects of S. carpocapsae on the phagocytic responsesof the hemocytes of R. ferrugineus and G. mellonella were also different in some respects, although in both cases S. carpocapsae was not encapsulated by the hemocytes. To compare the defensive capabilities of the humoral and cellular immune system of R. ferrugineus and G. mellonella, in particular against the Gram negative bacterium Xenorhabdus nematophila (Enterobacteraceae), known symbiont of S. carpocapsae, the minimum inhibitory concentration by hemolymph and hemocyte lysate was measured, which inhibits bacterial growth and colony forming units per milliliter (CFU / ml) of X. nematophila in the different hemolymphs. It was found that the number of CFU / ml of X. nematophila was a thousand times greater in G. mellonella than in the red palm weevil. This data may suggest reduced quantities of the entomapathogenicbacterium for the reproduction of the nematode, and therefore a reduced proliferation of S. carpocapsae in R. ferrugineus.