Potential of Entomopathogenic Nematode HbSD as a Candidate Biocontrol Agent against Spodoptera frugiperda

SIMPLE SUMMARY: Spodoptera frugiperda is a highly destructive and polyphagous pest that causes severe damage to various crops. Great efforts have been devoted to developing more effective and friendly strategies to minimize losses caused by S. frugiperda. In the current study, the infective capabilities of entomopathogenic nematode species HbSD, belonging to Hetrerorhabditis bacteriophora, were evaluated under laboratory, greenhouse and field conditions. The results showed that HbSD was highly lethal to S. frugiperda under laboratory/greenhouse conditions; however, the efficacy of HbSD decreased in the field trials. To better exploit HbSD as a biological agent, more efforts need to be carried out in future field work, including the optimization of production, formulation and application technology and other diverse factors. ABSTRACT: Spodoptera frugiperda is a highly destructive and polyphagous pest that causes severe damage to various crops, especially maize. The wide use of chemical insecticides to control S. frugiperda results in resistance against commonly used chemicals and resistant mutations will expand in populations accompanied by a spread to vulnerable areas. Consequently, more effective and friendly strategies must be explored to minimize losses caused by S. frugiperda. Entomopathogenic nematodes (EPN) are good candidates for the biological control of different species of insect pests, including S. frugiperda. In the current study, the infective capabilities of the EPN species HbSD, belonging to Hetrerorhabditis bacteriophora, were evaluated against S. frugiperda under laboratory, greenhouse and field conditions. In laboratory assays, HbSD was highly virulent against 3rd/5th instar larvae, which was related to HbSD concentration and exposure durations. In greenhouse assays, spraying aqueous HbSD also showed good performance in killing larvae on maize leaves. However, the virulence of HbSD decreased in field trials where many adverse factors affecting survival and efficacy were encountered by HbSD. Overall, our study provides an alternative EPN for the biological control of S. frugiperda with the potential to be developed as a sustainable option for efficient pest management.