Toxicity and efficacy of selected insecticides for managing invasive fall armyworm, Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae) on maize in Indonesia

The fall armyworm (FAW), Spodoptera frugiperda (J.E. Smith), has become an important maize pest that invaded Indonesia in the early 2019. As a highly polyphagous pest, S. frugiperda larvae feed on a total of 353 different host plants belonging to 76 plant families with causing yield losses up to 100%. To overcome this pest, maize grower in some countries using insecticides. Therefore, this study was conducted during 20192020 at Padjadjaran University, Faculty of Agriculture and at farmer's field in the Ciledug sub-district of Cirebon, West Java, Indonesia to evaluate the efficacy of several insecticides against S. frugiperda in laboratory and screenhouse to confirm field efficacy against natural infestation. Nineteen insecticides belonging to different chemical group were first tested for their toxicity against the larvae under laboratory conditions and the result will be used as a baseline susceptibility data to ditermine insecticide efficacy against of S. frugiperda in screenhouse and natural infestations in maize fields. The results showed that among insecticides tested, the highest mortality (>80%) were noted with emamectin benzoat, chlorfenapyr, phoxim, methomyl and indoxacarb under laboratory, screenhouse and field conditions. Among all the treatments, significantly higher maize yield of 29.28 t/ha was recorded in emamectin benzoat with 33.89% increase over control, followed by phoxim (29.92 t/ha), indoxacarb (27.5 t/ha), methomyl (26.88 t/ha) and chlorfenapyr (26.38 t/ha) with a per cent increase of 24.10, 14.68, 11.49 and 9.42%, respectively over control. The lowest yield was noticed in untreated control (24.11 t/ha). Emamectin benzoate was consistently more effective than other insecticides at suppressing S. frugiperda populations and protecting maize plants. Furthermore, these insecticides can be used as one of the components of integrated pest management of S. frugiperda and delayed the development of resistance against insecticides.