Fall armyworm outbreak in mainland Southeast Asia: Spatial mapping and impact on regional maize production

Abstract The rapid spread of fall armyworm (FAW), Spodoptera frugiperda , into Africa and Asia has raised concerns due to its significant damage to maize crops. Despite extensive efforts to combat FAW in Southeast Asia, gaining a comprehensive understanding of its impacts in this region is challenging. This study integrates information on FAW outbreak and maize production, with a particular focus on mainland Southeast Asia (MSEA), to support regional pest management strategies. We assessed the risk of FAW presence in MSEA by mapping its distribution in the Asia-Pacific region and compiled data on maize production and FAW infestation within MSEA. Our focus was on the spread of FAW and its impact on maize production, and ongoing issues following widespread FAW infestations during 2018–2019. The mapping suggests the widespread distribution of FAW in the Asia-Pacific region, posing a significant threat in high maize production areas. In MSEA, maize is crucial due to its extensive cultivation area, relatively high land productivity, and anticipated increase in feed demand. During 2018–2019, FAW infestations were widespread in MSEA, coinciding with decreased maize yields in Thailand. Despite a significant decline in FAW prevalence in Thailand and Vietnam after 2019, the findings indicate a persistent threat from FAW, which could still trigger local outbreaks and high infestation rates during specific maize growing seasons. This study underscores the threat of FAW in MSEA, considering its impact on the Asia-Pacific region and the agricultural economy within MSEA, and emphasizes the importance of regional control measures. Our cross-country research provides a foundation for effective regional cooperation to control FAW.