Sesamia cretica Ledereer
Taxonomic placing: Insecta, Holometabola, Lepidoptera, Noctuidae.
Common name: Sorghum borer, pink borer.
Geographical distribution: Northern and eastern Africa, the Mediterranean region, the Middle East to Pakistan and India.
Morphology: Female length about 15 mm, forewings yellow-brown, marked with darker brown spots, hindwings whitish. Geographic races with slightly different coloring of the forewings have been recorded. Larva red-pink, about 30-35 mm long.
Host plants: Various Poaceae (Gramineae) of economic importance, like maize (corn), sorghum, sugar cane and wheat, as well as many wild grasses.
Life cycle: A female lays 10-12 egg batches, coming to a total of about 100-300, and lives for less than one week. The young larvae crawl into leaves to feed and then tunnel into the stems. They feed for 4-6 weeks, boring several galleries there, and hibernate till the next growing season. The larvae pupate within the lower part of the stalks or between stems and leaf sheaths, near or underneath the soil surface. Adults emerge in the spring and start a new generation. In the Middle East the pest completes 3-4 partially-overlapping generation. The threshold of development is around 7°C and about 260 day degrees are required to complete a generation.
Economic importance: Sesamia cretica is listed as an A1 quarantine pest for South-East Asia. It is a major pest in Egypt, as its losses may exceed 60-70% of the maize and sugarcane crops. The larvae initially feed on the leaf epidermal tissues and then bore into the heart of the host plants. The plant’s growing points may be killed. Later in the season they feed on corn tassels and ears, and on the sorghum panicles.
Management
Monitoring: Light-trapping provides early warning of adult activity, especially of the first generation. Collecting egg masses, larvae and pupae from damaged stems indicates imminent infestations. The presence of one or more transverse rows of small circular holes across leaves of the whorl indicates pest attack.
Horticultural methods: Plowing or burning the corn and sorghum stubble will reduce the pest’s hibernating populations. The manipulation of maize and sugarcane planting dates may avoid the attack of first-generation moths. In Israel reductions in the pest’s numbers was attributed to a decline in the cultivation of sorghum.
Plant resistance: There is little evidence of progress in developing tolerance or resistance to S. cretica in corn. In Sudan stem thickness of sugarcane was correlated with resistance.
Biological control: Sesamia cretica is attacked by several hymenopterous parasitoids that attack its eggs and larvae. In Egypt Telenomus sp. (Scelionidae) destroyed over 70% of the egg masses of the pest. In addition, up to 90% of the newly hatched larvae were killed by spiders. The ant Paratrechina sp. was the most abundant and active predator of pupae in the soil. The pest is also susceptible to a granulosis virus, but its effect seems to be limited. The importance of the natural enemies of S. cretica is strongly indicated by high infestations that occur in areas which were heavily sprayed by insecticides, possibly due to the destruction of natural enemies.
References
CABI/EPPO, 2001. Sesamia cretica. Distribution Maps of Plant Pests, Map No. 241. Wallingford, UK: CAB International.
El-Amin, E.M. 1984. Relative susceptibility of seven sugar cane varieties to the stem borer, Sesamia cretica Led., under conditions of natural infestation at Sennar, Sudan. Beiträge zur Tropischen Landwirtschaft und Veterinarmedizin 22: 73-77.
Fediere, G., Taha, A., Ela, S.A., Lery, X., Zeddam, J.L., Veyrunes, J.C. and Giannotti, J. 1993. Account of a granulosis virus of Sesamia cretica Led. (Lepidoptera Noctuidae), a major pest of maize in north-east Africa: DNA characterization and viral diagnosis. Comptes Rendus de l’Academie des Sciences. Series 3, Sciences de la Vie: 316: 1350-1354.
Hafez, M., El-Kifl, A.H. and Fayad, Y.H. 1977. On the bionomics of Platytelenomus hylas Nixon, as egg parasite of Sesamia cretica Led., in Egypt. Bulletin de la Société Entomologique d’Egypte 61: 161-178.
Hafez, M., Salama, H.S. and Tolba, R.A. 1971. Investigations on the biology of the corn borer Sesamia cretica Led. (Lepidoptera — Agrotidae). Zeitschrift für Angewandte Entomologie 67: 38-44.
Melamed-Madjar, V., and Tam, S. 1980. A field survey of changes in the composition of corn borer populations in Israel. Phytoparasitica 8: 201-204.
Temerak, S.A. and Negm, A.A. 1979. Impact and differential effect of certain biomortality factors on the eggs and newly-hatched larvae of the pink borer, Sesamia cretica Led. (Lep., Noctuidae) on two sugarcane varieties. Zeitschrift für Angewandte Entomologie 88: 313-318.
Temerak, S.A. and Temerak, S.A. 1981. Qualitative and quantitative survey on the oophagous wasps attacking the pink borer, Sesamia cretica Led. (Lep., Noctuidae) on 3 gramineous crops in Upper Egypt. Zeitschrift für Angewandte Entomologie 91: 398-402.