Insect Pest Complex and Beneficial Insects Associated with Sweet Potato (Ipomoea batatas) (Lam.) in Southern Nigeria and Key Pests to Consider in Control Programmes

Abstract

Survey of insects on sweet potato, Ipomoea batatas (Lam) was conducted in Southern Nigeria during two cultivation periods within a season, March-July and August-December, to identify key pests and beneficial species that can be exploited in future biocontrol programmes.  The recorded insects consisted of thirty four different species and approximately 80% were defoliators. The Order Orthoptera had the highest number of individual species (29.4%), followed by Coleoptera and Lepidoptera pests in equal percentages (23.5%). Members from these Orders were the key pests and they were responsible for the most significant damage to the foliage and the tuber. Specifically, economic damage was caused by sweet potato butterfly (Acraea acerata), leaf folders (Brachmia and Helcystogramma spp), and sweet potato army worms (Spodoptera spp) and white plume moths (Pterophorus pentadactyla) and they are considered as potential targets of control programmes. The beneficial insects (5.9%), comprised of Adonis lady beetle (Hippodamia variegate), Transverse lady beetle (Coccinella transversalis) (Coleoptera: Coccinellidae), Black cockroach-wasp (Dolichurus spp), Cicada killer (Sphecius speciosus) and Praying mantids (Mantis religiosa) (Mantodea: Mantoididae). About 80-100% damage to foliage was recorded, indicating a severe pest pressure on sustainable sweet potato production under organic system in Southern Nigeria and the need to develop ecologically adaptable management approaches.