Insect pests of the kumara crop

Abstract

The kumara (Ipomoea batatas) or sweetpotato crop is propagated by sprouting roots stored from the previous season The warm humid conditions within propagation beds protected by plastic cloches produce densely packed sprouts that can support infestations of aphids such as the potato aphid (Macrosiphum euphorbiae) The sprouts are hardened by removal of the plastic covers and transplanted into freshly prepared fields where they are susceptible to the garden symphylid (Scutigerella immaculata) grazing on newly formed roots and greasy cutworm larvae (Agrotis ipsilon) chewing through plant stems at ground level The plants tend to develop a profuse canopy during the season which supports convolvulus hawk moth larvae (Agrius convolvuli) and large populations of soybean looper larvae (Thysanoplusia orichalcea) However foliage damage is generally not considered of economic importance considering the plants vigour Sweetpotato roots swell as the season progresses and are vulnerable to damage by black field crickets (Teleogryllus commodus) and larvae of whitefringed weevil (Graphognathus leucoloma) black beetle (Heteronychus arator) and pasture wireworm (Conoderus exsul) Following harvest larvae of the tropical armyworm (Spodoptera litura) and detritus moth (Opogona omoscopa) may cause considerable loss of root quality over prolonged storage periods