Changes in the hemolymph total protein of Galleria mellonella (Lepidoptera: Pyralidae) after parasitism and envenomation by Pimpla turionellae (Hymenoptera: Ichneumonidae)

Abstract

Venom from the endoparasitoid Pimpla turionellae L. (Hymenoptera: Ichneumonidae) contains a mixture of biologically active components, which display potent paralytic, cytotoxic, and cytolytic effects towards hosts. Here, we further investigate if parasitism or envenomation by P. turionellae alters total protein of its host Galleria mellonella L. (Lepidoptera: Pyralidae). Various venom concentrations representing doses previously determined to yield host responses yet fall below the calculated LD99 were used for pupae and larvae. Parasitization was only assayed for host pupa since P. turionellae females normally parasitize host prepupae and pupae in nature. Hemolymph total protein concentration remained relatively steady at all doses and at all time points tested in parasitized and venom-injected host pupae and larvae. The only exception to this trend was with the highest dose of venom (0.5 VRE) at 24 h for larvae that almost 2 times higher amount of protein were detected with regard to untreated ones. It is likely that the increase in protein concentration in a non-permissive host stage in the present study was induced by venom and/or general injury because the same trend was also observed in null- and PBS-injected larvae. However, neither of the treatments increased the protein concentration of G. mellonella larvae to the same extent that 0.5 VRE injection did, indicating that the increase observed in the latter treatment was not simply the result of wounding or injection of fluid. Thus, we favor the possibility that stress proteins may play a role in this event.