Seasonal Distribution of Spodoptera frugiperda Smith (Lepidoptera: Noctuidae) in Ethiopia

Abstract

The alien invasive insect pest, Spodoptera frugiperda Smith (Lepidoptera: Noctuidae), commonly referred as to fall armyworm (FAW), is causing significant losses to maize production in Africa since its detection in 2016. Despite being the primary insect pest of the main food crop in the country, researchers are more focused on control methods’ development. There is no or little research done on the seasonality of the pest which greatly helps in timing intervention time by farmers. The primary purpose of this research was to determine how S. frugiperda in maize fields changed with the seasons. S. frugiperda surveys were carried out in Ethiopia's major maize-growing regions. These include Afar, Benishangul Gumuz, Amhara, Tigray, South Nation, Nationality and Peoples (SNNP), and Oromia in the dry and rainy seasons, respectively, from 2018 to 2019 and 2019 to 2020.The survey sites were purposively selected based on production statistics of maize and S. frugiperda occurrence reports in Ethiopia. From different regions, a total of 480 maize-producing farmers’ fields were surveyed: 240 fields in the dry season and 240 fields in the rainy season. Out of the 240 maize fields surveyed during the dry season, 218 fields were infested by S. frugiperda. During the rainy season, out of 240 fields, 146 fields were infested by S. frugiperda. The dry season had an average percentage of infestation of 35.5 to 70%, while the rainy season ranged from 20 to 70%. The average percentage of infested plants per plot for the dry season was higher in Afar, Amhara, Tigray and Oromia, while the lowest was recorded at Benishangul Gumuz and SNNP. During the dry season, the average infestation of S. frugiperda in the regions ranges from 22.6 to 52.2 percent, and during the rainy season, it ranges from 11.3 to 46.6 percent. Afar (46.6 percent), Oromia (22.0 percent), Amhara (18.8 percent), SNNP (13.6), Benishangul Gumuz (16.1 percent), and Tigray had higher average percentage infestations during the wet season (11.3). The findings revealed that S. Frugiperda is an economically important maize pest both in the off-season and in the rainy season, while the off-season infestation is slightly larger than the rainy season.

Keywords:Cropping season, Fall armyworm, Infestation, Invasive, Dry season, Rainy season, Population density

DOI: 10.7176/ALST/98-01

Publication date:June 30^th 2023