Standardizing in-vivo mass production technique for entomopathogenic nematode Heterorhabditis bacteriophora (Nematoda: Heterorhabditidae)

Abstract

Biological control is a need of hour to protect crops in a sustainable manner without disturbing ecological balance. Entomopathogenic nematodes (EPNs) have a potential to be used effectively and selectively as inoculative agents for classical biological control. EPNs production can be done in both in vivo and in vitro. In vivo method was preferred during present studies aimed at standardizing mass production technology for Heterorhabditis bacteriophora that can easily be adopted at small scale farms. Different cost-effective diets used for rearing Galleria mellonella (GWM) (Lepidoptera: Pyralidae) were standardized to show their effect on development and production of in vivo mass production of EPNs on GWM larvae. Diet consisting of maize flour (400 g), wheat flour, wheat bran, milk powder (200 g each), yeast (100 g), glycerol (350 ml) and honey (350 ml) was found best among all the diets tested for rearing GWM with 93.5 percent larvae surviving to cocoon formation stage and average larval weight of ca 300 mg for inoculating 5 GWM larvae in 50 mm diameter inoculation arena, 0.5 ml of formalin solution (0.1 percent) was found to create optimum moisture in the arena to give quick mortality of GWM. The inoculation dose (200 ± 2.1 IJs/larva) of EPNs and temperature of 20 °C were found to give highest harvest of infective juveniles (IJs/larva) from the host. Enhanced effectiveness of EPN application can be assisted through advanced diet which is most significant factor influencing consistent development of GWM in turn affecting EPNs maximum harvest.