Abstract :
Laboratory experiments were performed to evaluate the pathogenic and lethal effects of the genera entomopathogenic nematodes, (EPNs) (Heterorhabditis bacteriophora Poinar HP88) and Sc (Steinernema carpocapsae All strains, (Steinernema carpocapsae, Steinernema. scapterisi and Steinernema. glaseri) on greater wax moth larvae, Galleria mellonella, at the three concentrations; 20IJs, 50IJs and100IJs (infective juveniles) after different times, 6, 12, 24 and 48hrs of exposure times. The mortality percentage of EPNs was determined on G.mellonella larvaefor each concentration. It was found that the infectivity of nematode strains against G. mellonella larvae was concentration-dependent; i.e. the mortality percentage increased as the infective juvenile concentrations increased. The mortality percentages among G. mellonella larvae after 48hrs post-treatment by all EPNs strains were highly significant increased at 100 IJs/L for each concentration. The treatments at 20 IJ/L noticed that, LT25 was 10.17hrs for G. mellonella larvae treated with S. carpocapsae after48hrs post-treatment.Also, results indicated S. glaseri gave the highest mortality rate for the tested larvae reached to 96.66 %, followed by S. carpocapsae achieved 96.16%, but the H. bacteriophora HP88 recorded 84.24 % mortality after four times of exposure. Meanwhile at 50IJ/L data cleared that, LT25 value was 7.36hrs for G. mellonella larvae treated with S. carpocapsae while S. carpocapsae treatment gave the highest significant mortality for the tested larvae reached to 94.45 % followed by 94.25% for S. glaseri, but H. bacteriophora recorded 86.01 % mortality. The results of the study noticed that, LT25 value was 3.26hrs for G. mellonella larvae treated with S. scapterisi also showed that S. carpocapsae treatment gave the highest significant mortality for the tested wax moth larvae recorded 98.18 % followed by S. glaseri achieved 98.09% and the H. bacteriophora recorded 92.77 % mortality at 100IJ/L after 48hrs of treatments. Also, data showed a strong coefficient correlation between the testedENPs against G. mellonella larvae. Also, there were inverse relationship between the times of infection and concentrations. Our results suggest that H. bacteriophora, S. carpocapsae, S. scapterisi and S. glaseri can be used as valuable tools in biological control programs oflast instar larvae of G. mellonella.
Keyword :
Galleria mellonella; Heterorhabditis bacteriophora; Steinernema carpocapsae; Steinernema scapterisci; Steinernema glaseri; mortality; toxicity