Cellular immune of fourth instar larvae of the potato tuber moth, Phthorimaea operculella (Lepidoptera: Gelechiidae) against to pathogenic fungi Beauveria bassiana

Background and Objectives
Knowledge on the characteristics of insects immune system can play an important role in the adoption of biological control methods such as the use of entomopathogenic fungi. Insects with a strong immune system exhibit the development of infection.
Materials and Methods
In this study, the immune responses of fourth instars larva of the potato tuber moth were investigated against two isolates of entomopathogenic fungi Beauveria bassiana includingFashand and 47 (isolated from the soil of the Fashand region and isolated from the Abr jungle of Shahrood, respectively). Concentration of 10⁵ spores / ml of each isolate was injected to the larvae. Control larvae were treated with distilled water. After 3, 6 and 10 hours, the abundance of hemocytes was evaluated in treated larvae.
Results
The results showed that after 3 hours the total number of hemocytes, plasmatocytes and granulocytes increased significantly compared to control. However, the abundance of these hemocytes decreased gradually after 10 hours post injection. 6 hours after injection, prohemocytes also showed significant decrease in numbers. The amount of enzyme activity of phenoloxidase was measured. The maximum activity of Phenoloxidase enzyme was in the isolates of Fashand and 47, respectively, in 3 hours after spores injection.
Discussion
Recognition of hemocytes and study of the interaction of pathogenic agents with immune system of Potato tuber moth has been conducted for the first time and could be used as a basis for future investigation in the context of the feasibility of the biological control of this dangerous pest of potato with Beauveria bassiana.