Analysis of Fall armyworm infestations on rainy season crops under different cropping systems in two agroecological zones in Burkina Faso, West Africa

The Fall armyworm (FAW), Spodoptera frugiperda, was first reported in a few regions of Burkina Faso in 2017. Since then, it has continued to spread and damage maize crops in the country, thereby threatening food security. This study, conducted three years later, aimed to assess the pest status on major rainy season crops, and the effects of cropping systems, crop diversity, and phenology in 11 localities of Sudanian and Sudano-Sahelian zones in Burkina Faso. Two sampling periods, the first conducted at the beginning of the rainy season and the second at the end of the season, were considered. Maize was the most FAW-infested crop, mainly as monocrops (84–88% of surveyed fields). Sorghum, pearl millet, cowpeas, and peanuts were the secondary infested crops, more infested when intercropped with maize. Maize fields were more FAW-affected in the Sudanian zone, whereas the secondary infested crops were significantly more affected in the Sudano-Sahelian zone. The highest field infestation rates were recorded during the second survey period, coinciding in most cases (> 90%) with the flowering and post-flowering of maize. Then, FAW attacks were found in vegetative, flowering, and post-flowering cereal organs. Despite the technical recommendations, most farmers (57.30 ± 10.34 and 66.78 ± 6.74% in the Sudanian and Sudano-Sahelian zones, respectively) did not apply insecticide in infested maize fields. Thus, in 3 years, the FAW has become an important pest of cereals, specifically maize, in the main agricultural zones of Burkina Faso. These results should be taken into account to develop effective control actions against FAW.