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A field screening trial undertaken in Uganda showed that a number of Musa L. (Musaceae) cultivars and hybrids displayed high levels of resistance to banana weevil, Cosmopolites sordidus (Germar) (Coleoptera: Curculionidae), while most highland banana cultivars tended to be susceptible to weevil attack. In this study, research was undertaken to determine modalities of resistance to banana weevil. Laboratory studies suggested that all cultivars were attractive to the weevil and that females freely oviposited on all cultivars. While some differences were found between cultivars in attractivity and egg numbers, these were not related to subsequent damage. Therefore, antixenosis does not appear to play an important role in host-plant resistance to banana weevil. Larval survivorship rates in living corms were, for the most part, low on resistant cultivars, suggesting that antibiosis mechanisms offer the primary avenues of resistance. In the laboratory, development was slower on some resistant cultivars although survivorship rates on excised corm material were not as well related to levels of resistance as that on living material. Sap appeared to play a minor role in reducing egg eclosion rates on some resistant cultivars. Methanol extracts from Kayinja, a resistant cultivar, inhibited larval development on corms of susceptible cultivars in the laboratory. [ABSTRACT FROM AUTHOR]

Abstract  : Potato (Solanum tuberosum L.) is a nutritious starchy tuber crop consumed as a staple food in most potato growing countries. Its productivity and production are limited by climate change; thus, it is of utmost importance to tap into the diversity of germplasm resources, therefore, diversifying the potato varieties available for production. The objectives of this study were to determine the phenotypic diversity among the selected Agricultural Research Council-Vegetable, Industrial and Medicinal Plants (ARC-VIMP) potato varieties for tuber yields and processing quality and to determine the correlation between measured traits. Two imported and 22 local potato varieties were planted in three different environments in South Africa. Significant (P < 0.001) differences in the tested varieties across all environments were observed for all measured traits. High broad-sense heritability (> 0.6) was observed for most of the traits, except for fry colour and the yield of unmarketable tubers. Nine ARC varieties and three standard varieties were associated with high tuber yield and quality traits, indicating their suitability for the fresh market and processing industry. Variety Mondial and five ARC varieties were associated with high tuber yield, indicating their suitability for the fresh market. Varieties released between 2004 and 2021 had high tuber yield, dry matter and specific gravity compared to the standard varieties and varieties released between 1980 and 1999, although there were slight differences in the magnitudes of their traits measured. These varieties could be recommended for commercial production for specific markets and for use as potential parents for further genetic improvement of the potato crop. [ABSTRACT FROM AUTHOR]