Biocontrol potential of entomopathogenic nematodes against invasive fall armyworm, Spodoptera frugiperda in India

The invasion of fall armyworm, Spodoptera frugiperda (J. E. Smith) (Lepidoptera: Noctuidae), has threatened the researchers to develop an effective biological control strategy at the global level. Larval stage remains in maize whorl, and precise placement of entomopathogenic nematodes (EPNs) opens up wide opportunity for biological control. The study evaluated the virulence of Heterorhabditis indica (Poinar) and Steinernema carpocapsae (Weiser) against all the developmental stages of S. frugiperda. The results revealed that both the tested EPNs had a high rate of ovicidal, larvicidal and pupicidal effects on S. frugiperda. The EPNs also significantly affected the adults, resulting in the deformation and death. The invasion efficiency and reproduction assays of EPNs revealed that H. indica had higher invasion efficiency and reproduction rates compared to S. carpocapsae on different larval stages and pupae. EPNs also reproduced in the adult cadavers of S. frugiperda emerged from the EPN-treated pupa. A preliminary study on the effect of EPN application on S. frugiperda was carried out under semi-field conditions by pre-releasing third instar larvae to whorl of corn plants. Application of H. indica and S. carpocapsae @ 500 IJs mixed with five gram of sand was applied manually to whorl led to mortality of 86.67 and 83.33%, respectively. The study demonstrated that both the EPN species tested showed high puissance as bio-control agents against S. frugiperda, having the potential for its successful management.