acerata is a production constraint in some localities of Eastern Africa.
Outbreaks are sporadic and seasonal and usually occur at the beginning of the
dry season. Complete defoliation and/or repeated defoliation results in reduced
Africa (Kenya, Tanzania, Uganda, Rwanda, Burundi, Congo,
Zambia, Ethiopia and Nigeria) and South America
caterpillars feed on the leaves of
sweetpotato, generally working from the edge inward, and leaving only the midrib
and main veins. They can completely defoliate plants.
Young caterpillars hatch in large groups inside a nest formed of several
leaves joined with web. They feed on the upper leaf surface, and the
leaves of the nest become brown and shrivelled and covered with frass.
Older larvae become solitary and feed at night, usually remaining on the soil
Egg. The pale yellow eggs measure about 0.5 mm
wide and 0.7 mm long, and are laid on the leaf surface in groups of several
larvae are greenish-black and covered with fleshy, branching spikes.
Caterpillars reach a size of 20-24 mm before pupating.
Pupa. The pupae
are cream to blackish with brownish banding on the back, and measure 12-15 mm.
The adult sweetpotato butterfly has orange wings with
brown margins. Wingspan is 30-40 mm.
A. acerata is found in all zones of
sweetpotato production in Eastern Africa, but is considered a constraint in
relatively dry agroecological zones. Outbreaks are common in Rwanda.
Females lay eggs in batches of 70 to 500 eggs on both
surfaces of the leaves. Development is temperature-dependent. The egg stage
takes 5 to 10 days. The larva passes through five larval stages in 16 to
26 days. The larvae are concentrated in a protective webbing for the first 2
weeks after hatching. They then become solitary and hide from the sunlight on
the ground during the day. For pupation the caterpillars crawl up the plant or any
convenient support, such as tall grass or a wall bordering the sweetpotato
field. Here the pupa is suspended in a vertical position. The pupal stage takes 4
to 10 days.
The insects prefer sweetpotato. Observations were made
that A. acerata completed all its life stages on several Ipomoea
spp., which are indigenous to Africa.
The "nests" of young caterpillars can consist
of several leaves and are easily spotted in the field. Pretty, orange
butterflies, swarming over a sweetpotato field, are easily recognisable.
The traditional method of controlling outbreaks has been
to handpick and destroy nests of young caterpillars. A limiting factor might be
lack of labour.
Severe outbreaks might warrant the use of contact
No parasitoids were recovered from eggs or adults. Larvae
have been observed to be parasitised by the hymenopterans Apanteles acraea
Wlkn, Zenillia vara Cuarran, Charops sp. and Meteorus sp.
and one dipteran, Carcelia normula. Total parasitism could reach 25% in
the dry season. Pupae have been observed to be parasitised by two species of Brachymeria
(Chalicididae) while the ants Camponotus rufoglaucus Forel and Pheidole
megacephala (F.) preyed on larvae. The pathogenic fungus Beauveria
sp. was observed on larvae in the field during the rainy season.
sweetpotato with onion and/or the silverleaf desmodium, Desmodium uncinatum,
might reduce the number of eggs laid by the females on sweetpotato.
Ames, T., Smit,
N.E.J.M., Braun, A.R., O’Sullivan, J.N., and Skoglund, L.G. 1996. Sweetpotato:
Major pests diseases, and nutritional disorders. International Potato Center
(CIP). Lima, Perú. 152 p.
Hitimani, N., 2001. Host plant finding by Acraea
acerata Hew. (Lepidotera: Nymphalidae), the sweet potato butterfly:
Implications for pest management. PhD thesis, The University of Edinburgh, U.K.,
Lefèvre, P.C., 1948. Acraea acerata Hew. parasite
de la patate douce. Bulletin Agronomique du Congo Belge. 39: 49-76.
N.E.J.M., Lugojja, F., Ogenga-Latigo, M.W. 1997. The sweet potato butterfly (Acraea
acerata Hew., Nymphalidae): a review. International Journal of Pest
Management, 43: 275-278.
by: Nicole E.J.M. Smit