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Eldana saccharina Walker, 1865 - African Sugarcane Stalkborer

Summary

Indigenous to Africa, the African sugarcane stalkborer is widely distributed in sub-SaharanAfrica. Sugarcane is the main crop host of the African sugarcane stalkborer but it will also attack maize (where it is a relatively minor pest), sorghum and rice. It attacks maize plants late in their development when it can affect grain filling which results in yield loss.

Common Names

Sugarcane stalkborer, African sugarcane stemborer, Eldana borer

Synonyms

Eldana conipygaStrand, 1912

Taxonomic Position

Phylum: Arthropoda; Class: Hexapoda (Insecta);Order: Lepidoptera;Family: Pyralidae;Subfamily: Gallerinae

Origin and Distribution

Indigenous to Africa, the African sugarcane stalkborer is widely distributed in sub-Saharan Africa includingBurundi, the Democratic Republic of Congo, Kenya, Rwanda, Tanzania and Uganda.

Description

Eggs

The eggs of the African sugarcane stalkborer are yellow and oval and laid in batches and in maize usually on dry dead maize leaves. They become pink just before emergence.

Larvae

The African sugarcane stalkborer larvae are light-brown to dark-grey coloured with brown pinacula (hardened – sclerotized – areas that indicate points of muscle attachment), covered with very small dark coloured spots and have a distinct brown prothoracic shield (a plate on the dorsal surface of the thorax). The head is reddish-brown to dark-brown. Larvae may be distinguished from other stemborer larvae by the circular arrangement of crochets (hooks) on the prolegs, pinacula and tubercles (small rounded projections) along the body. 

Adults

The adult African sugarcane stalkborer is small with a wingspan of 35 mm. The forewings are pale brown with two dark spots in the centre and elongate with a rounded front edge. The hindwings are whitish with a short fringe and brown longitudinal veins. At rest the wings are folded over the abdomen in such a manner that their outer edges are parallel to each other, and they cover the lighter coloured hind wings which are hidden from view.

Similar Species

Both the adult or larval stages are unlikely to be confused with any other stem borers present inAfrica.

Life Cycle

Eggs are laid in batches of 50 - 100 eggs in folds of dead leaves, behind the leaf sheath or on dry leaves at the bases of plants or on plant debris on soil. Females may lay 400-600 eggs in their lifetime. Eggs hatch within five-six days.

Young larvae feed externally on the green surface of the plant and later tunnel into the stems where they eat out tunnels within which they pupate. 

Larvae can develop in 21 days but development may last up to three months. The larvae do not go into a state of suspended development (diapause ). Adults emerge in 7-14 days after the onset of pupation and only live for a few days.

Pest Destructive Stage

Larva (caterpillar )

Host Range

Sugarcane is the main crop host of the African sugarcane stalkborer but it will also attack maize, sorghum and rice. In the wild its hosts are wild grasses (Poaceae) such asGuinea grass (Panicum maximum), wetland sedges (Cyperaceae) such as papyrus (Cyperus papyrus), rushes (Juncaceae) and typha (Typhaceae).

Host Lifestage Affected

Vegetative growing stage

In Eastern Africa, Eldana saccharina is often only a minor pest on maize but is a major pest on sugarcane. Because the pest attacks plants later in their development, infestations affect grain filling which results in yield losses.

Host Plant Part Affected

Stems

Damage Symptoms

Stem tunnelling and/or breakage; holes in tunnelled stems often with frass hanging from them; cob damage; Reduced grain yield (weight).

Pest Management

Detection methods

African sugarcane stalkborer infestations may be detected by walking through young crops looking for characteristic feeding marks on funnel leaves, the presence of dead hearts and holes in tunnelled stems. Samples of affected stems can then cut open to find caterpillars and pupae.

African sugarcane stalkborers may be detected in older crops and in crop residues by taking random samples of stems to dissect to find caterpillars and pupae.

Cultural practices

Intercropping maize with non-hosts crops like cassava or legumes like cowpea can reduce spotted stemborer damage. Alternatively, maize can be intercropped with a repellent plant such as silver leaf desmodium (Desmodium uncinatum) and a trap plant, such as Napier grass (Pennisetum purpureum), molasses grass (Melinis minutiflora) as a border crop around this intercrop to protect maize from stemborers. The trap plant draws the adult female away from the crop. More eggs are laid on the trap plant than on the crop but the larvae develop poorly or not at all on the trap plant. This practice is known as "push-pull".

Biological control

Biological control by two parasitic wasps, Cotesia flavipes and Xanthopimpla stemmator, that attack the spotted stemborer, has shown good results. Cotesia flavipes locates the stemborers while they are feeding inside the plant stems. The wasp lays about 40 eggs into a stemborer. Upon hatching the larvae of the parasitic wasp feed internally in the stemborer, and then exits and spin cocoons. Xanthopimpla stemmator operates similarly but attacks the pupae. Habitat management practices that conserve these parasitoids and predators like ants and earwigs can help in the control of the spotted stemborer.

Chemical control

Chemical control can be achieved by applications of granules or dusts to the leaf whorl early in crop growth to kill early larval instars. This method has limited effectiveness once the larvae bore into the stem. Neem products (powder from ground neem seeds) are reportedly effective and may be applied to the leaf whorl in a 1:1 mixture with dry clay or sawdust. Pesticides are poisons so it is essential to follow all safety precautions on labels.

Sources of Information and Links

Assefa Y., Conlong D.E. and Mitchell A. (2006). Status of Eldana saccharina (Lepidoptera: Pyralidae), its host plants and natural enemies in Ethiopia. Bulletin of Entomological Research 96, 497 – 504.

Bosque-Pérez, N.A.  (1995).  Major insect pests of maize in Africa:  biology and control.  IITA Research Guide 30.  Training Program, International Institute of Tropical Agriculture (IITA), Ibadan, Nigeria.  30 p.  Second edition.

Girling D.J. (1978). The distribution and biology of Eldana saccharina Walker (Lepidoptera Pyralidae) and its relationship to other stem-borers in Uganda. Bulletin of Entomological Research 68, 471 – 488.

Kfir R., Overholt W.A., Khan Z.R. and Polaszek A. (2002). Biology and management of economically important lepidopteran cereal stem borers in Africa. Annual Review of Entomology, 47: 701-731.

Overholt W.A, Maes K.V.N and Goebel F.R. 2001. Field guide to the stemborer larvae of maize, sorghum and sugarcane in Eastern and Southern Africa. ICIPE Science Press, Nairobi, Kenya.

Polaszek A. (ed.) (1998). African cereal stemborers; economic importance, taxonomy, natural enemies and control. CAB International, Wallingford, Oxon, UK. 530pp.

Editors

Anne M. Akol, Makerere University; Maneno Y. Chidege, Tropical Pesticides Research Institute; Herbert A.L. Talwana, Makerere University; John R. Mauremootoo, BioNET-INTERNATIONAL Secretariat.

Acknowledgments

We recognise the support from the National Museums of Kenya, Tropical Pesticides Research Institute (TPRI) - Tanzania and Makerere University, Uganda. This activity was undertaken as part of the BioNET-EAFRINET UVIMA Project (Taxonomy for Development in East Africa).

Contact

BioNET-EAFRINET Regional Coordinator: [email protected]

BioNET Secretariat Tropical Pesticides Research Institute Lucid SwedBio Busitema University National Museums of Kenya SDC
BioNET-EAFRINET Kenya Agricultural Research Institute CABI Makerere University
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