Immunological Responses of Sesamia cretica to Ferula ovina Essential Oil

The current research was performed aiming to investigate the effects of Ferula ovina essential oil on the fourth instar larval hemogram of Sesamia cretica. Four main sorts of circulating hemocytes, including prohemocytes, plasmatocytes, granulocytes (GRs), and oenocytoides, were identified in the fourth instar larvae. Treatment of the larvae with the concentration of 1000 ppm of the essential oil led to an enhancement of the total hemocyte and GR count followed by a dose-dependent decrease at the concentrations of 2500 and 7000 ppm. Plasmatocyte numbers declined in all the treatments with more significant effects at increased doses. The greatest numbers of GRs, plasmatocytes, and total hemocytes were found after 48 h of treatment. The highest phenol-oxidase activity was recorded 12 h after treatment at the concentration of 2500 ppm. The highest effect on nodule formation was exerted by the concentration of 7000 ppm 12 h after treatment. The results of the present study clearly indicated that the treatment of larvae by the essential oil of F. ovina decreased the numbers of total and differential hemocyte counts although phenol-oxidase activity and the number of nodules showed no decline in the treated larvae. These results demonstrated that Ferula ovina essential oil has a significant effect on the immune ability of the studied insect and can be useful and usable for future research to practical management of this pest.