Biochemical Effects of Heterorhabditis bacteriophora, Steinernema carpocapsae, Steinernema scapterisi and Steinernema glaseri on Galleria mellonella Larvae (Lepidoptera: Pyrallidae)

The present study aimed to investigate the biochemical effect of four entomopathogenic nematode strains, Heterorhabditis bacteriophora poiner (HP88), Steinernema carpocapsae (S.c), Steinernema scapterisi (S.s)andSteinernema glaseri (S. g) against the last larval instar of the greater wax moth G. mellonella. The biochemical variations due to nematodes infection were estimated after 6, 12, 24 and 48hrs exposure times and by 20, 50 and 100 infective juveniles (IJs) concentrations. The content of total protein showed significant decreases at all treatments compared with control, meanwhile, a significant increase was determined after 24hrs of treatment with 100 IJs of both (S. c) and (S.s) strains. The most pronouncing reduction estimated 48 hrs post-treatment with (S. c) strain and scored 15.58±1.5 mg/g. b. wt. with a reduction percent -74.60% post-inoculation with 50 IJ. Clear dysfunction in protease, Aspartate aminotransferase (AST) and Alanine aminotransferase (ALT) activities demonstrated after all treatments. At 100 (IJs), all treatments provoked a significant reduction in protease activity except after 48hrs of treatment with HP88, a non-significant increase (82.98±2.43 μg tyrosine/min/ g. b. wt.) was reported. All tested entomopathogenic nematodes induced a high significant increase in AST activity compared to control.At 100 (IJ) the increasing percentage reached its maximum level (195.60%) after 24hrs of the treatment with (S. g) as relative activity of control. Fluctuation in ALT activity by elevation and inhibition was recorded in comparison with the control experiment. High significant increase of the enzyme activity from 6 to 48hrs (604.64±4.46 and 518.96±4.43 μg pyruvate/g. b. wt.) with percentages of 88.97% and 114.10% clearly determined at 100(IJ) with (S. c) treatment compared to control. On the other hand, a highly significant decrease in ALT activity was recorded (167.82±1.84 μg pyruvate /g. b. wt.) with a reduction percentage of -64.20 % of treatment with (S. g) after 24hrs at 50 IJs as compared with control.