Virulence potential of two entomopathogenic nematodes, their associated bacteria, and its metabolites to larvae of Pieris brassicae L. (Lepidoptera, Pieridae) in cabbage under greenhouse and field bioassays

The cabbage butterfly ( Pieris brassicae L.) is a major insect pest of cabbage in Pakistan. Heterorhabditis bacteriophora (at 1500 infective juvenile/ ml concentraction) , Steinerma glaseri (at 1500 infective juvenile/ ml concentration) , H. bacteriophora + S. glaseri (at 1500 infective juvenile/ ml concentration), Xenorhabdus spp., (at 4 × 10 12 concentration) Photorhabdus spp., (at 4 × 10 12 concentration) metabolites of Xenorhabdus spp. (at 50% concentration) and metabolites of Photorhabdus spp (at 50% concentration) were sprayed on cabbage hybrid CB-60 grown in pots placed in the greenhouse. After 7 days, the highest P. brassicae larval mortality (90.43%) was observed where H. bacteriophora + S. glaseri were sprayed. In field experiment, best-performing treatments from greenhouse experiment were selected i.e. H. bacteriophora + S. glaseri (at 1500 infective juvenile/ ml concentration), Xenorhabdus spp., (at 4 × 10 12 concentration) and metabolites of Xenorhabdus spp. (at 50% concentration) were sprayed on a highly susceptible cabbage hybrid (CB-60). Heterorhabditis bacteriophora + Steinerma. glaseri @ 1500 infective juvenile/ ml was found to be more superior with maximum mortality (80.43) of cabbage butterfly larvae in comparison with other treatments. From the present study, it may be concluded that EPNs ( H. bacteriophora and S. glaseri ) application is more effective as compared to their symbiotic bacteria and metabolite for cabbage butterfly management.