Severity of the fall armyworm, Spodoptera frugiperda (J. E. Smith) (Lepidoptera: Noctuidae) damage and maize yield as influenced by Telenomus remus (Nixon) (Hymenoptera: Scelionidae) under sole maize and maize-cowpea intercrop in Southern Guinea Savanna, Nigeria

Background Fall armyworm (FAW), Spodoptera frugiperda (J. E. Smith, 1797) (Lepidoptera: Noctuidae) is one of the major devastating insect pests of maize worldwide. The pest is difficult to control owing to its high reproductive capacity, wide host range, high migratory ability and adaptability diverse conditions. Biological control using the egg parasitoid, Telenomus remus (Nixon) (Hymenoptera: Scelionidae) has emerged as a promising management strategy. Intercropping maize with legumes such as cowpea ( Vigna unguiculata (L.) Walp.) has shown potential to suppress FAW population. Results Field trails in a split-plot randomized complete block design with three replications evaluated FAW damage severity and yield increase in sole maize ( Zea mays L) Sammaz 52 (SM) and maize-cowpea intercrop (varieties ‘Sweet beans’ [C1] and ‘Sokoto white [C2]) under three control measures: T. remus release (TR), cypermethrin (SI) and water control (W). Treatments consisted of SM+TR, SM+SI, SM+W, M+C1+TR, M+C1+SI, M+C1+W, M+C2+TR, M+C2+SI and M+C2+W. Data on FAW incidence and severity, cob count, cob weight and grain weight were subjected to ANOVA ( p <0.05). At 3 WAP (Weeks after planting), SM+W plots had a significantly (p<0.05) higher FAW severity (57.48%) while the lowest severity occurred in M+C1+TR (28.99%) and M+C2+TR (31.26%). Intercropped plots with T. remus produced significantly higher grain weight in M+C1+TR (1.97 kg) and M+C2+TR (1.73 kg). Consequently, M+C2+TR (59%) and M+C1+TR (54%) achieved higher yield increase percentage. Conclusions Telenomus remus suppressed fall armyworm infestation on maize in treated plots owing to high parasitization of host eggs, resulting in lower FAW incidence and severity, higher cob count, cob weight, grain weight and yield increase. Intercropping maize with legumes proved effective in the management of FAW due to beneficial interactions between the planted crops; legumes retain the parasitoid, while the parasitoid obtains nectar and shelter.