Agroecological Factors Determining Occurrence and Abundance of the Fall Armyworm (Spodoptera frugiperda) on the Outlooks of Maize Production in Benin

Abstract

The fall armyworm (Spodoptera frugiperda J.E. Smith) is one of the most notorious pests of maize crops worldwide. However, few studies have shown the influence of agroecological factors and future distribution patterns of the FAW in Benin. This study assessed the abundance of the FAW in the Territorial Agricultural Development Agency Division 4, with extrapolation of the data in relation to environmental variables in the study areas leading to future FAW distributions in these regions. For this purpose, FAW surveys were carried out in 80 maize fields at three stages of maize development (sowing, flowering and maturity). Magurren's formula and Shannon's diversity index were used to assess species abundance. Mixed effects Poisson and MaxEnt models were developed to investigate the distribution patterns of FAW and the relative influence of agroecological factors on FAW presence and abundance. Results showed that FAW abundance varied from one region to another, depending on the stage of maize development and the areas. All model parameters were statistically significant at the 5% level (p-value < 0.05) except sowing stage (p-value > 0.05). Flowering stage showed a significant negative effect on FAW abundance, with an IRR ≈ 0.31, indicating that FAW abundance at maturity is reduced by about 69% compared to flowering. In contrast, the effect of sowing stage was not significant (IRR ≈ 1.30). These results also suggest that pest management strategies can be adapted to new climatic conditions. This would allow a proactive rather than a reactive approach.