Effects of symbiotic status on cellular immunity dynamics in Sitophilus oryzae

Many insects maintain intracellular symbiosis with mutualistic bacteria that improve their adaptivecapabilities in nutritionally poor habitats. Adaptation of insect immune systems to such associations hasbeen shown in several symbiotic consortia, including that of the rice weevil Sitophilus oryzae with thegammaproteobacterium Sodalis pierantonius. Although authors have mostly focused on the role of humoralimmunity in host-symbiont interactions, recent studies suggest that symbiotic bacteria may alsointerfere with the cellular, hemocyte-based, immunity. Here, we have explored hemocyte dynamics inS. oryzae in the presence or absence of S. pierantonius, and in response to bacterial challenges. We haveidentified five morphotypes within larval hemocytes, whose abundance and morphometry drasticallychange along insect development. We show that hemocytes make part of the weevil immune system byresponding to pathogenic infections. In contrast with previous results on other insect species, however,our analyses did not reveal any symbiotic-dependent modulation of the hemocyte global population