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This study investigated maize farmers’ knowledge, control methods, and perception of the invasive and highly destructive insect pest, fall armyworm (Spodoptera frugiperda) in southwest Nigeria. A four-stage sampling procedure was employed in selecting 195 maize farmers in the study area. Data were obtained with the aid of structured questionnaire and analysed using percentages, means, standard deviations, and chi-square test. The majority (88.7%) of respondents observed fall armyworm attack within two months after sowing, only 30.8% of them reported total damage to maize plants by fall armyworm. Most (75.9%) of the respondents could describe the destructive larval stage of fall armyworm, 58.5% of respondents exclusively applied synthetic insecticides for fall armyworm management. The most common insecticides used by respondents were organophosphates (37.2%), pyrethroids (29.0%) and avermectins (18.2%). Perception of fall armyworm damage as a serious and worrisome problem was very high (4.82) amongst maize farmers. Strong and significant association (χ2 = 41.3) was found between farmers’ agroecological zones and the severity of fall armyworm damage reported. Integrated pest management approach is a sustainable alternative to the sole use of insecticides and should be promoted. Information provided in the study will enhance decision-making for fall armyworm management interventions in southwest Nigeria.

The fall armyworm, Spodoptera frugiperda is an invasive and trans-boundary lepidopteran insect pest. This moth species is native to the Americas but has been reported on the African continent in recent times, where its polyphagous larva has caused much damage to field maize. The fall armyworm occurs in two highly destructive strains – the ‘corn’ and ‘rice’ strains. Though morphologically identical, the two strains have different host preferences and varying susceptibility to conventional insecticides. Management of fall armyworm on maize and other crops will be enhanced by the molecular identification of existing strain or strains in local populations of the pest in existing African agro-ecologies. However, information on the presence of both strains is scarce and unclear for the different agro-ecological zones of Nigeria. Using a Polymerase Chain Reaction – Restriction Fragment Length Polymorphism (PCR-RFLP) method, strain identification analysis of larvae from 22 maize farms spread across the humid forest, derived savannah and southern guinea savannah agro-ecological zones of Nigeria was carried out. Results showed that all the larvae screened belong to the corn strain implying that only the corn strain is present on maize in the agro-ecological zones. Knowledge of the type of fall armyworm strain in African agro-ecologies is useful for the selection of appropriate bio-control agents and chemical pesticides against the pest on the continent.

Detailed information on insect pests of stored grains in Nigeria is lacking. A two-year survey was conducted to determine the species composition and abundance of insects associated with maize, millet, rice, sorghum and tamarind in eighteen locations across five agro-ecological zones in Nigeria. Sixteen coleopteran, lepidopteran and hymenopteran species were associated with stored products, with high species richness on cereal grains but low species richness on tamarind. Most of these insects are polyphagous on cereal grains, whereas the tamarind weevil Sitophilus linearis (Herbst, 1797) (Curculionidae), and Caryedon serratus (Oliver, 1790) (Chrysomelidae) were found only on tamarind in this study. The maize weevil Sitophilus zeamais (Motschulsky, 1758), rice weevil Sitophilus oryzae (Linneaus, 1763), lesser grain borer Rhyzopertha dominica (Fabricius, 1792) (Bostrichidae), rusty grain beetle Cryptolestes ferrugineus (Stephens, 1831) (Laemophloeidae) and red flour beetle Tribolium castaneum (Herbst, 1797) (Tenebrionidae) were most abundant on stored grains. The tamarind weevil, C. serratus and the sawtoothed grain beetle Oryzaephilus surinamensis (Linneaus, 1758) (Silvanidae) were most abundant on tamarind. The hymenopterans Theocolax elegans (Westwood, 1874) (Pteromalidae), Anisopteromalus calandrae (Howard, 1881) (Pteromalidae) and Cephalonomia waterstoni (Gahan, 1931) (Bethylidae) were the dominant parasitoids of larvae and pupae of the storage pests. Simpson index of diversity of insect species across locations ranged from low (0.63) to high (0.89).

The fall armyworm (Spodoptera frugiperda) is an invasive and highly destructive insect pest that has caused extensive damage to maize in Africa since its first report on the continent in 2016. Information on fall armyworm infestation and damage within African agroecologies is essential for the development of appropriate pest management strategies, but these are scant in Nigeria. Consequently, in this study, fall armyworm infestation levels and severity of damage to maize in the three major maize-growing agro-ecological zones (humid forest, derived savanna, and southern guinea savanna) of southwestern Nigeria was investigated using standard field sampling protocols. Results showed that maize infestation and damage severity varied across agroecological zones, with the humid forest being the most impacted. Information provided will enhance decision-making for effective management of the fall armyworm in southwestern Nigeria.