Cotesia favipes (CAM) (hymenoptera: Braconidae) supresses immune responses in diatraea favipennella (BOX) (lepidoptera: Crambidae)

Abstract

The present research aimed to elucidate which aspects of immune responses in Diatraea favipennella are suppressed by the parasitoid Cotesia favipes, thus, ensuring parasitism success. We investigated the presence of apoptosis in fat body cells through the TUNEL technique. According to the results, reduced levels of nitric oxide and phenoloxidase activity were observed in larvae parasitized for three days, and reduced total number of hemocytes, after three and seven days. An increase in plasmatocytes and decrease in spherulocytes numbers were observed in the differential count on the third day of parasitism. The number of melanized microspheres in parasitized larvae was low and indicated less intense melanization. The ultrastructural analysis confrmed the immunosuppressive effect of C. favipes on the encapsulation response of D. favipennella because only the formation of hemocytes capsules, adhered to the microspheres’ surface, was evidenced in non-parasitized caterpillars. The effect of parasitism was also recorded on the third day with the presence of hemocytes and apoptosis in fat body cells, including aspects of degeneration in the latter. We concluded that C. favipes suppresses cellular and humoral immunological responses in D. favipennella and drastically affects the host’s fat tissue.