Influence of agricultural practices on Spodoptera frugiperda (JE Smith) infestation, natural enemies and biocontrol in maize

Abstract

Maize (Zea mays L.) production in Africa is threatened by the recent invasion of the fall armyworm (FAW), Spodoptera frugiperda (JE Smith). The management of this pest is laborious and requires effective, sustainable and environmentally friendly control approaches. The present study investigated the natural enemies associated with S. frugiperda in maize fields through three climatic zones in Benin. Besides, the impact of different agricultural practices on its infestation and the performance of biocontrol agents were assessed. Larvae were collected from 67 maize fields and transferred to the laboratory, incubated and monitored for parasitoid emergence. The complex of natural enemies recorded in this study consisted of: entomopathogenic fungus Metarhizium sp., nematode Hexamermis sp. and parasitoids Chelonus bifoveolatus, Coccygidium luteum, Charops sp. and Drino quadrizonula. The results revealed that maize fields sown after soybean or cotton crops and those in which insecticides and herbicides were applied were associated with higher FAW infection rates by Metarhizium sp. The use of agricultural inputs led to lower FAW parasitism by Hexamermis sp. Regarding FAW infestation, the probability of high damage scores was higher in maize fields cultivated after fallow or cotton crops and in fields with mixed crops or those in which herbicides or relatively high fertilizer rates were applied. These findings provide several insights on the interaction between agricultural practices and FAW natural enemies that can be used for the implementation of an effective integrated management system for this pest in Benin or Africa.