- Title
- Diversity and distribution of lepidopteran stem borers and their wild host plants in Western Cape and KwaZulu-Natal provinces, South Africa
- Creator
- Kokwana, Bongiwe
- Subject
- Stem borers--South Africa Pests--South Africa Grain--Diseases--South Africa
- Date
- 2016
- Type
- Thesis
- Type
- Masters
- Type
- Entomology
- Identifier
- http://hdl.handle.net/10353/11729
- Identifier
- vital:39101
- Description
- Lepidopteran stem borers are infamous among cereal crops and sugarcane growers because of their pests status in these crops. Lepidopteran stem borers often infest cereal crops such as maize (Zea mays L.), sorghum (Sorghum bicolor L.), pearl millet (Pennisetum glaucum L.), sugarcane (Saccharum spp.). However, in natural habitats, the stem borers feed on a wide variety of wild host plants species in the Poaceae, Cyperaceae and Typhaceae families. Some wild host plants in close approximation of cultivated fields act as reservoirs for stem borers during the absence of cultivated crops. Understanding of the diversity of the stem borers, their host plants and their interactions was very important in development of management strategies for the stem borer populations. For an example, grasses such as Napier grass (Pennisetum purpureum Schumach.) and Sudan grass(Sorghum vulgare var. Sudanense (Piper) Hitchc.) act as trap plants whereas other grasses such as Molasses grass (Melinis minutiflora P. Beauv.) and legume silverleaf (Desmodium uncinatum (Jacq.) DC.) act as repellents to stem borer moths. In South Africa, studies on the diversity and distribution of lepidopteran stem borers in wild habitats are limited. Previous studies concentrated on diversity, abundance, and distribution of stem borers and their natural enemies on cultivated crops because of the economic importance of cultivated crops. In view of the foregoing, this study was conducted to investigate the diversity and distribution of lepidopteran stem borers and their host plants in wild habitats in the Western Cape and KwaZulu-Natal Provinces of South Africa and to generate mtDNA COI sequences of the stem borer species in natural habitats. These sequences can be accessed in databases and assist in identification of previously unknown stem borers in cultivated crops. Therefore this study contributes to development of monitoring and early identification tool of the stem borer movements between host plants assemblages. Surveys were conducted in Western Cape and KwaZulu-Natal provinces, South Africa during the rainy season of 2014 and 2015 in 38 localities to catalogue the diversity of lepidopteran stem borers in wild host plants. The sites visited belonged to five vegetation types: grassland, the Indian Ocean coastal belt, savanna, forest, and wetlands. A total of 237 lepidopteran stem borers was collected during study yielding 21 species that belonged to Noctuidae (Acrapex sp. 89, Acrapex sp. 90, Acrapex sp. 92, Acrapex sp., Acrapex minima, New genus NG11), Sesamia calamistis Hampson, Sesamia sp., Sesamia natalensis Le rü sp. nov., Sesamia nov sp. 4, Sesamia nov sp.36, Conicofrontia bipartita Hampson, Conicofrontia sesamoides Hampson, Conicofrontia diamensa Hampson, Pirateolea piscator Fletcher , Sciomesa mesophaea Aurivillius), Crambidae(Chilo partellus Swinhoe and Calamotropha paludella Hibner) Pyralidae (Phycitiinae sp. 1 and Phycitiinae sp. 2) and Tortricidae were recorded from 20 wild host plant species. Stem borer wild host plants species were Cymbopogon dieterlenii Stapf ex Schweick.,Cymbopogon nardus (L.) Rendle, Cymbopogon pospischilii (K. Schum.) C.E. Hubb., Digitaria macroglossa Henrad, Eriochloa meyeriana (Nees) Pilg.,Eriochloa fatmensis (Hochst. &Steud.) Clayton, Imperata cylindrica (L.) Raeusch., Miscanthus capensis (Nees) Andersson, Paspalum urvillei Steud., Panicum maximumJacq., Pennisetum purpureum Schumach., Phragmites australis (Cav.) Trin. Ex Steud.,Rottboellia cochinchinensis (Lour.) Clayton, Setaria homonyma (Steud.) Chiov.,Sorghum arundinaceum (Desv.) Stapf.,Cyperus divesDelile, Cyperu sdistans Pursh, Cyperus fastigiatus Rottb., Cyperus sexangularis Nees and Typha latifolia (L.).The diversity of stem borer species varied among vegetation types, host plants, and altitude. Morphological identification of specimens from these surveys indicated a high diversity of stem borer species in the Noctuidae family, followed by Pyralidae, Crambidae, and Tortricidae respectively. Of all the stem borers collected in the two provinces, noctuid species were most abundant in all vegetation types from low to high altitudes representing 62.45percent, whereas pyralids, crambids, and tortricids made up 26.58percent, 9.28percent, and 1.69percent respectively. The diversity and distribution of stem borers were affected by latitude. KwaZulu-Natal had higher latitudes ranging between -28.37717˚ and -31.07800˚ and had higher diversity, distribution and the of stem borers host plants, while Western Cape Province had lower diversity and distribution at latitudes ranging between -34.00280˚ and -34.05343˚. Morphological identification of stem borers was complemented with the mtDNA cytochrome oxidase I gene (COI) to investigate evolutionary relationships between the stem borer species collected in this study. Of the 12 sequences searched from the databases and the Genebank only five sequences were identified to species level; UFH024 was identified as Sciomesa mesophaea, the other four were identified as Conicofrontia sesamoides, Conicofrontia bipartita; and the first ever record of Calamotropha paludella in South Africa and Pirateolea piscator. Five sequences; UFH026, UFH028, UFH029, UFH030, UFH032 were only identified to order.
- Format
- 76 leaves
- Format
- Publisher
- University of Fort Hare
- Publisher
- Faculty of Science and Agriculture
- Language
- English
- Rights
- University of Fort Hare
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