Chemical resistance of cowpea genotypes to aphids (aphis craccivora koch) and bruchids (callosobruchus maculatus F.).
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Date
2024
Authors
Siyunda, Aaron Chimbelya
Journal Title
Journal ISSN
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Publisher
The University of Zambia
Abstract
Cowpea [Vigna unguiculata (L.) Walp] is an annual legume, considered important as a cash and nutritional security grain legume in the semi-arid regions of sub-Saharan Africa. Cowpea yields in the sub-Sahara African region are low partly due to several biotic stress factors, which includes several insects. One of the major insect pests at the developmental stage in cowpea production is the aphid species, Aphis craccivora Koch and at post-harvest stage, the bruchid (Callosobruchus maculatus F.). Therefore, this research seeks to contribute to knowledge on useful genetic materials and associated traits for cowpea resistance to aphids and bruchids in cowpea genotypes by firstly, identify cowpea genotypes that exhibit multiple resistance to aphid and bruchid infestation, secondly, by identify aphid and bruchid resistance metabolites linked to the genes associated with multiple insect resistance in cowpea and lastly, by determining the heritability of genes associated with production of metabolites linked to multiple insect resistance in cowpea. The germplasm used consisted of three parental lines namely; Musandile (MS-parent), Bubebe (BB-parent), and Lutembwe (LT-parent) obtained from Zambia Agricultural Research Institute (ZARI), one landrace variety namely; Namuseba and 101 advanced mutant lines (7th generation mutants) provided by the Department of Plant Sciences under the School of Agricultural Sciences, at the University of Zambia, and 5 purelines from the International Institute of Tropical Agriculture (IITA). The non-restricted aphid screening, was conducted in the field at the University of Zambia (UNZA) (Lat= -15.39058o, Long = 28.32813o ), and the restricted aphid screening was conducted in the greenhouse at Natural Resources Development College (NRDC) ((Lat= -15.3833o , Long= 28.3667o ),) in Lusaka Province, Zambia. Bruchid screening was conducted in the insectarium laboratory, Department of Plant Science, School of Agricultural Sciences at the University of Zambia. The metabolite analyses (qualitative analysis) were conducted in the chemistry laboratory at the University of Zambia, and by Food and Drugs laboratory (quantitative analysis). Significant differences at a 5% level of significance were observed among 110 genotypes under consideration with regard to aphid and bruchid resistance. Mutant lines were identified to possess different resistance traits MS1-8-2-6-8-1 (aphid resistance only), LT11-5-2-2-2 (bruchid resistance only), and BBBT1-11 (aphid and bruchid resistance). Phenolics were identified to be highly responsible for the multiple resistant trait expressed by BBBT1-11, under the control of three or more genes. BBBT1-11 can be utilized in breeding programs with a target of breeding multiple insect resistant cowpea genotypes. Further research should also be conducted in order to genotype the BBBT1-11 and identify the QTLs responsible for the trait observed in BBBT1-11.
Description
Thesis of Master of Science in Plant Breeding and Seed Systems.