Effect of infectivity
concentration for Mass Propagation of Heterorhabditis indica in Different Host
Manochaya S. and Ramakrishna Krishnaveni
Res. J. Biotech.; Vol. 20(10); 305-310;
doi: https://doi.org/10.25303/2010rjbt3050310; (2025)
Abstract
Entomopathogenic nematodes (EPNs) are promising biological control agents against
several insect pests. This work assessed the effectiveness of three EPN inoculation
techniques: spread plate, immersion and shaking on five insect hosts: Bombyx mori
larvae (BML), Bombyx mori pupae (BMP), Galleria mellonella larvae (GML), Philosamia
ricini larvae (PRL) and Philosamia ricini pupae (PRP). The spread plate method consistently
resulted in the highest mortality, with BML exhibiting ~72% mortality followed by
BMP (~64%), GML (~66%), PRL (~54%) and PRP (~44%). Mortality was significantly lower
in the immersion and shaking methods (p < 0.0001). A dose-dependent response was
observed with EPN concentrations ranging from 50 to 1000 IJs/mL where PRL showed
the steepest increase in mortality (R² = 0.61) and PRP showed the lowest susceptibility
(R² = 0.30).
The emergence of infective juveniles also increased linearly with concentration,
being highest in BML (R² = 0.90) and BMP (R² = 0.87) and lowest in PRP (R² = 0.94
but with lower absolute numbers). Control host GML maintained consistent mortality
(~63–74%) and supported IJ emergence (~9–27), confirming its reliability as a baseline
comparator. These findings highlight the influence of inoculation technique and
host-specific susceptibility on EPN effectiveness, offering insights for optimizing
biocontrol applications in integrated pest management programs.
