Whitefly resistance in African cassava genotypes

Abstract

Whitefly (Bemisia tabaci), a major pest and vector of viruses in cassava, is the greatest current threat to cassava production in sub-Saharan Africa (SSA). Research efforts have focused on management of the two viral diseases: cassava mosaic disease (CMD) and cassava brown streak disease (CBSD), and have ignored the whitefly vector that is driving the spread of the viruses, causing CMD and CBSD in SSA. The objective of this study was to evaluate cassava genotypes for resistance to B. tabaci based on field infestation and damage in Uganda. The study was carried out in four sites with diverse agroecologies including: Namulonge, Kasese, Ngetta and Serere during 2015 and 2016.Whitefly nymph abundance and feeding damage were assessed on each test genotype from 3 to 6 months after planting (MAP). In 2015, the highest broad sense heritability estimates were 39% (4 MAP) and 53% (5 MAP) for whitefly nymph abundance and feeding damage, respectively. In 2016, broad sense heritability estimates were 23% (3 MAP) and 41% (4 MAP) for whitefly nymph abundance and feeding damage, respectively.Analysis of variance of whitefly nymph abundance showed a significant (P< 0.05) location × genotype × season interactions at 3, 4, 5 and 6 MAP. There were also significant (P< 0.05) location × genotype × season interactions at 3 and 4 MAP for whitefly feeding damage. Ten genotypes showed good levels of resistance to whitefly infestation and feeding damage including: UG120202, UG120174, NASE13, UG120160, UG120286, UG120293, UG130075, CSI-142, CS1-144 and UG130085. These genotypes may serve as parental materials for breeding programmes for whitefly and viral disease control.

Evaluation of the Efficacy of Flupyradifurone against Bemisia tabaci on Cassava in Tanzania

“…These results suggest that Mkuranga1 is less suitable as a host for B. tabaci than other cassava varieties, an observation that confirms results obtained from a study in coastal Tanzania that did not include any whitefly-control measures, in which Mkuranga1 had the lowest whitefly adult abundance of the seven varieties evaluated [ 40 ]. The performance of Mkuranga1 suggests that resistant or tolerant varieties have an important role to play in management of both vectors and viruses, as noted elsewhere [ 34 , 41 , 42 , 43 , 44 ].…”

The metabotyping of an East African cassava diversity panel: A core collection for developing biotic stress tolerance in cassava

“…Historical breeding efforts of African cassava, documented since in the 1930s [1,8,11,13] suggests a high level of in-breeding probably resulting in scarce diversity in the current national stock collections and fields. Indeed, the most promising candidates within the 5CP collection, which represent a subset of national collections, as potential sources of both whitefly and disease resistance seem to be concentrated in the Ugandan and Tanzanian lines (Table 1) which are the ones presenting the highest level of duplication and homology.…”

“…Since the raise and spread of African cassava whitefly superabundant populations, the development of improved cassava varieties possessing virus and whitefly resistance has constituted one of the core milestones of national breeding programs in Sub-Saharan African countries and international consortiums [8,11,12]. Efforts in finding natural sources of African whitefly (Bemisia tabaci) resistance have been focused on collections of local landraces and advanced lines originally developed for virus resistance [13][14][15][16][17] with the intention of pyramiding both disease and vector resistance into farmer-preferred varieties adapted to local agroecosystems.…”

Cassava (Manihot esculenta) dual use for food and bioenergy: A review

“…However, a limited number of studies have been conducted mainly to identify sources of pest resistance in cassava populations. There are African and South American genotypes that have been reported to have some levels of resistance to whiteflies (Gwandu et al, 2019; Omongo et al, 2012). Ten cassava genotypes evaluated in Uganda showed resistance to whitefly infestation and feeding damage, suggesting that they could be used as parental materials in breeding programmes for both whitefly and viral disease resistance (Gwandu et al, 2019; Omongo et al, 2012).…”