Fall Armyworm, Spodoptera frugiperda Infestations in East Africa: Assessment of Damage and Parasitism.

The fall armyworm (FAW), Spodoptera frugiperda, threatens maize production in Africa. A survey was conducted to determine the distribution of FAW and its natural enemies and damage severity in Ethiopia, Kenya and Tanzania in 2017 and 2018. A total of 287 smallholder maize farms (holding smaller than 2 hectares of land) were randomly selected and surveyed. FAW is widely distributed in the three countries and the percent of infested maize fields ranged from 33% to 100% in Ethiopia, 93% to 100% in Tanzania and 100% in Kenya in 2017, whereas they ranged from 80% to 100% and 82.2% to 100% in Ethiopia and Kenya, respectively, in 2018. The percent of FAW infestation of plants in the surveyed fields ranged from 5% to 100%. In 2017, the leaf damage score of the average of the fields ranged from 1.8 to 7 (9 = highest level of damage), while 2018, it ranged from 1.9 to 6.8. In 2017, five different species of parasitoids were recovered from FAW eggs and larvae. Cotesia icipe (Hymenoptera: Braconidae) was the main parasitoid recorded in Ethiopia, with a percent parasitism rate of 37.6%. Chelonus curvimaculatus Cameron (Hymenoptera: Braconidae) was the only egg-larval parasitoid recorded in Kenya and had a 4.8% parasitism rate. In 2018, six species of egg and larval parasitoids were recovered with C. icipe being the dominant larval parasitoid, with percentage parasitism ranging from 16% to 42% in the three surveyed countries. In Kenya, Telenomus remus (Hymenoptera: Scelionidae) was the dominant egg parasitoid, causing up to 69.3% egg parasitism as compared to only 4% by C. curvimaculatus. Although FAW has rapidly spread throughout these three countries, we were encouraged to see a reasonable level of biological control in place. Augmentative biological control can be implemented to suppress FAW in East Africa.

The Efficacy of Selected Synthetic Insecticides and Botanicals against Fall Armyworm, Spodoptera frugiperda, in Maize.

Fall armyworm (FAW) was reported for the first time in Africa in 2016. FAW is widely distributed in Ethiopia, causing significant damage to maize. Nine synthetic insecticides belonging to different chemical groups and 11 pesticidal plants (botanicals) were tested for their efficacy against FAW under laboratory, greenhouse, and field conditions. In the laboratory, Radiant, Tracer, Karate, and Ampligo caused over 90% larval mortality 72 h after application. Malathion had moderate activity, causing 51.7% mortality 72 h after application, while Carbaryl was less effective, causing 28% mortality 72 h after application. In the greenhouse experiment, all synthetic insecticides reduced foliar damage to maize compared to the untreated control. Chemical sprays did not affect plant height, stem thickness, or leaf number. The highest fresh weight (471 g) was obtained from plants treated with Radiant. Among the botanicals tested, Azadirachta indica, Schinnus molle, and Phytolacca dodecandra resulted in the highest percentage larval mortality (>95%) 72 h after application. In the field, non-treated control plants showed extensive leaf injury compared to the synthetic insecticide- and botanical-treated plants. The synthetic insecticides and botanicals that showed high efficacy against FAW larvae can be used as components for integrated pest management (IPM) plans for FAW under smallholder farmer conditions in Ethiopia and elsewhere in Africa.