Pathogenicity of five entomopathogenic nematodes from Gansu Province on Spodoptera frugiperda

This study used a series of bioassays to examine the efficiency of using 5 species and 10 indigenous isolates of entomopathogenic nematodes to control the 2^nd instar larvae of Spodoptera frugiperda. The pathogenicity of entomopathogenic nematodes with a high virulence were tested against prepupae and pupae. All isolates, showed infectivity to the 2^nd instar S. frugiperda larvae; Steinernema feltiae 0663PG and Steinernema krussei 0657L were particularly effective. After exposing one 2^nd instar S. frugiperda larva to 160 S. feltiae 0663PG for 72 h, the mortality rates were 100% for the former. When exposed to 50 S. krussei 0657L, the 2^nd instar S. frugiperda larvae had a mortality rate of 80%. The S. frugiperda prepupae pupated successfully after 2 d of being infected with S. feltiae 0663PG. When exposed to 3200 S. feltiae 0663PG for 15 d, S. frugiperda pupae had eclosion rates of 96.67%. However, after exposing one S. frugiperda pupae to 12800 S. feltiae 0663PG for 13 d, S. frugiperda pupa had eclosion rates of 93.33%. The mortality rates of S. frugiperda prepupae and pupae were less than 10%. The results showed that S. feltiae 0663PG has great potential as a biological control for S. frugiperda larvae. The S. frugiperda prepupae and pupae were insensitive to the entomopathogenic nematodes, and infections of the latter had no significant effect (P > 0.05) on the rate and time of the emergence of S. frugiperda pupae.