ISSN: 0041-3216 (Online), 0041-3216 (Print)
Volume 72 Number 4
The biology of Acraea acerata Hew and the damage on sweet potato [Ipomoea batatas (L.) Lam] in south-eastern Nigeria
The life cycle of Acraea acerata Hew was studied in the laboratory at temperature and relative humidity ranges of 26-30ºC and 40-90%, respectively. Male and female insects were caged in pairs and fed with a 10% sugar solution. Sweet potato leaves were provided as oviposition substrates. Eggs were laid in clusters and these hatched at the end of a 6-day incubation period. The larvae passed through between five and seven instar stages, the life cycle was completed between 45 and 48 days. The young instars (1st and 2nd) fed in clusters and skeletonized the leaves, while the mature larvae were solitary and fed by making large openings usually along the leaf veins. Infestation with five to ten 2nd instar larvae per plant, at six weeks after planting, caused increases in the yield of sweet potato foliage over those of the controls, but these were not significantly different (P > 0.05). This was due to a compensatory response by the plants to the insect damage. The highest population of 20 larvae depressed foliage yields by 20.0 to 37.3% as compared with the controls. This was estimated to reduce root tuber yield by 18.7% at the end of the crop growing cycle.
Keywords: Acraea acerata; Biology; Sweet potato