Galleria mellonellalarvae fat body disruption (Lepidoptera: Pyralidae) caused by the venom ofHabrobracon brevicornis(Hymenoptera: Braconidae)

Abstract

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 A 2 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

Parasitoid venom alters the lipid composition and development of microorganisms on the wax moth cuticle

“…The envenomation of wax moth larvae by H. brevicornis causes lysis of fat body cells by controlled necrotic death (necroptosis) and the release of lipids, resulting in the hyperlipidemia of the hemolymph (Kryukova et al, 2020). In addition, larval hemolymph becomes richer in amino acids and carbohydrates after envenomation by Habrobracon spp.…”

“…In addition, larval hemolymph becomes richer in amino acids and carbohydrates after envenomation by Habrobracon spp. (Becchimanzi et al, 2017;Kryukova et al, 2020). Moreover, envenomation of the host by the parasitoid leads to changes in gut microbiota and the development of spontaneous infection (Polenogova et al, 2019).…”

“…Hydrocarbons are transported through the hemolymph by lipophorin to epidermal cells; however, the mechanisms by which they cross through the integument are insufficiently understood (Bagnères & Blomquist, 2010). Habrobracon venom disrupts fat body cells and different types of hemocytes (Kryukova et al, 2015(Kryukova et al, , 2020, which may lead to the release of hydrocarbons to the hemolymph. We speculate that elevated hydrocarbon amounts in the epicuticle of envenomated larvae were due to the incomplete cessation of lipid transport.…”

“…It is possible that changes in fungal development are caused by the increased levels of carbohydrates in the cuticle. A substantial increase in the amounts of carbohydrates in the hemolymph of G. mellonella and S. littoralis after envenomation by Habrobracon has been reported (Becchimanzi et al, 2017;Kryukova et al, 2020). It is well known that carbohydrates stimulate the germination and mycelial growth of entomopathogenic, saprotrophic, and phytopathogenic fungi.…”

“…Increases in lipid amounts may be useful for the development of parasitoid larvae, as many parasitic insect species exhibit reduced lipogenesis, i.e., they consume host lipids instead of synthesizing them de novo (Visser & Ellers, 2008). In a previous study (Kryukova et al, 2020), we established that wax moth larvae, Galleria mellonella (L.) (Lepidoptera: Pyralidae), envenomated by Habrobracon brevicornis (Wesmael) [syn. Habrobracon hebetor (Say)] (Hymenoptera: Braconidae) were also characterized by fat body disruption and increased levels of total lipids and trehalose in the hemolymph.…”