Effect of infection by Beauveria bassiana on hemolymph and free amino acid in Xylotrechus rusticus

The purpose of this study was to clarify changes in the immune response of the hemolymph after infection with Beauveria bassiana in Xylotrechus rusticus larvae in order to reveal the physiological regulating mechanism of the pathogenic fungi. The results showed that B. bassiana was infectious to X. rusticus adults. The main infection sites were the thoracic internodes, lower wings, and abdomen. After infection with B. bassiana, the number of blood cells in the X. rusticus larvae was significantly higher than the control. The number of plasma cells and granulocytes in the hemolymph of the insect was largest. The total number of blood cells was mainly affected by the changes in number of plasma cells and granulocytes. The trehalose content in X. rusticus larvae after B. bassiana treatment continued to decrease compared to the control. The glucose content in the larvae hemolymph increased first, then decreased. The acid trehalase activity was significantly higher than the control, and the high activity was maintained for 60-84 h after infection with B. bassiana. Nineteen kinds of free amino acids were detected in the larvae hemolymph infected by B. bassiana. After infection, the total amount of free amino acids in the larvae hemolymph presented a trend where the amount first declined, then rose. Proline, arginine, and glutamine were the main amino acids required for the growth and development of B. bassiana in X. rusticus larvae. The amount of hemolymph and free amino acids played an important role in immunity during the infection with B. bassiana.

Automated summary

This study elucidated changes in the immune response of Xylotrechus rusticus larvae after infection with Beauveria bassiana, revealing physiological regulating mechanisms such as increased blood cell counts, alterations in free amino acids, and elevated enzyme activities.