Changes in hemocytes of Plutella xylostella (Lepidoptera:Plutellidae) in response to Bacillus thuringiensis and thermal stresses

The circulatory system is involved in the transport and storage of food and defense against microorganisms. The success rate of this system depends on the number and type of blood cells and their proper function against contaminants in the body. In the present study, the effect of Bacillus thuringiensis and temperature stress was investigated on homocyte abundance and phenol oxidase activity in fifth larvae of Plutella xylostella. In the first experiment, rapeseed leaves were treated with sub–lethal concentrations of bacteria and fifth instar larvae were bled at 12 and 24 hours after feeding on the leaves. In the second experiment, the larvae were exposed to 4 and 30 degrees Celsius for 12 hours and temperature stress was examined on their homocytes. The results showed that feeding on canola leaves infected with bacteria after 12 and 24 hours caused a significant increase in total cells, plasmotocytes and granulocytes and phenol oxidase activity compared to the control. Temperature stresses also increased the number of homocytes and phenol oxidase activity compared to the control, which was more significant in larvae that tolerated high temperature stress. Certainly, additional research is needed to be able to evaluate the possible use of microbial control methods against cabbage willow by recognizing the safety characteristics.