The ability of Habrobracon brevicornis venom to elevate the nutritional suitability of a host by affecting the host larvae fat body condition was studied. To understand whether H. brevicornis crude venom impacts the host biochemical profile, the concentrations of total lipids and main sugars in the host larvae lymph were analyzed. All measurements were carried out during the first 3 days after envenomation. A significant increase in the lipid level was fixed only on the second day after envenomation. A significant increase in the total trehalose count was detected during all 3 days, while a significant increase in glucose concentration was noted only on the first day. Well-observed disruptions were fixed in thin and semithin sections of the G. mellonella larval fat body starting from the second day after envenomation. Significant increases in both phospholipase A2 and C enzyme activity as well as acid proteases were detected in the wax moth fat body after envenomation during all experimental times. At the same time, imbalances in the antioxidant system, including changes in the activities of superoxide dismutase, peroxidases, catalase, and glutathione-S-transferase, were detected. The reliable increase in the expression of the gene encoding Hsp70 was fixed both for 24 and 48 h after envenomation, while a reliable increase in the expression of the gene encoding inhibitor of apoptosis protein was detected only 24 h after wax moth larvae envenomation. Considering the absence of DNA fragmentation, the imbalance in the "ROS/antioxidants" system, and the increased activity of phospholipases and acid proteases in the fat body cells from envenomated wax moth larvae, we can hypothesize that the fat body disruption occurs in a necrotic manner. The results of the work expand the knowledge about the biochemical aspects of interaction between ectoparasitoids and their hosts.
Keywords: ectoparasitic wasp; fat body; host-parasitoid interactions; manipulation of the metabolism.
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