Potential use of Heterorhabditis bacteriophora IJs for the control of Spodoptera frugiperda (Smith, 1797) in small Andean productive systems: culture, harvest and application
摘要
Armyworm Spodoptera frugiperda is a significant invasive pest of maize crops, and its control often relies on genetically engineered maize expressing Bacillus thuringiensis proteins. However, insect resistance to these proteins has been reported, and small-scale Andean maize production systems frequently lack access to these hybrids. To explore alternative control measures, this study evaluated the susceptibility of S. frugiperda larvae to the entomopathogenic nematode Heterorhabditis bacteriophora. Galleria mellonella was used as a host for mass rearing of H. bacteriophora; initially, infective juveniles (IJs) concentrations of 100, 200, or 300/larvae were inoculated into this host and their survival, as well as the number of recovered nematodes was evaluated. Additionally, fourth or fifth-instar larvae of S. frugiperda were exposed to 400, 800, or 1200 IJs and their mortality was assessed by 120 h. Nematode production began 17 days post-infestation, peaked at 19 days after the infestation of G. mellonella and declined by 21 days. The efficacy of H. bacteriophora in controlling S. frugiperda was influenced by both the initial infestation concentration and the duration of exposure. After 72 h, a mortality rate of 25% was observed at the lowest concentration, while the highest concentration resulted in 75% mortality. No significant differences were observed when comparing treatments in the mean lethal time (LT50), and complete mortality occurred within 120 h. Conclusively, these results demonstrate the potential of H. bacteriophora as a biological control agent for S. frugiperda in small-scale Andean maize production systems, offering a sustainable and environmentally friendly alternative to chemical control methods.