Evaluation of cowpea accessions for resistance to flower bud thrips (Megalurothrips sjostedti) in Mali (original) (raw)
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Cowpea is an important grain legume in sub Saharan Africa where its protein rich grains are consumed. However, its production is hampered by some major constraints including flower bud thrips (Megalurothrips sjostedti) that can cause 60% to total crop yield loss. Therefore, the development of resistant varieties becomes necessary. Thus, the present study was designed to determine the inheritance and elucidate the genetic control of cowpea resistance to thrips. Generation mean analysis model was exploited to assess the mode of inheritance of the resistance to flower bud thrips in cowpea using six generations (P1, P2, F1, F2, BC1P1 and BC1P2) derived from cross of Komcallé and Sanzi. Parameters such as number of flowers abortion per plant, number of pods per plant, thrips damage, number of thrips per plant and 100 seeds weight were exploited for progenies evaluation. Generation mean analysis revealed the existence of additive (a), additive x dominance (ad) and dominance x dominance (dd) effects as the mode of gene action predominantly involved into cowpea for thrips resistance control. Number of effective factors for thrips damage control varied from 3 (number of aborted flowers per plant) to 6 (weight of 100 seeds). Estimated Broad and narrow sense heritabilities for flower bud thrips resistance were low indicating large effect of the environment on the trait.
STABILITY AND EXTENT OF RESISTANCE OF COWPEA LINES TO FLOWER BUD THRIPS IN UGANDA
Cowpea (Vigna unguiculata (L.) Walp.) is a legume attacked by several field insect pests, with flower thrips (Megalurothrips sjostedti Trybom) being the most damaging. It causes 20 to 100% yield losses. Cowpea constitutes an important source of protein for resource poor households in Africa. The objective of this study was to identify cowpea lines that are resistant to flower thrips as a step in developing sustainable thrips management strategies. Seventy two cowpea cultivars were screened in three locations and two rainy seasons in Uganda, for thrips damage and yield components. Up to 11 cultivars (IT2841*Brown (1.50), MU20B (1.58), EBELAT*NE39 (1.61), WC17 (1.63), WC29 (1.65), MU24C (1.65), WC5 (1.66), NE46 (1.67), WC30 (1.68), NE67 (1.69), and NE51 (1.71)) were the most resistant and stable across locations. However, thrips damage was negatively correlated with the number of days to flowering (r = -0.32), indicating that the resistance in the cultivars was explained by the flower thrips infestation escape due to later flowering. Cultivar MU9 was high yielding (813.87 kg ha-1) and the most adapted genotype to all the locations; while cultivars WC26, NE48, and NE5 were the most adapted to Arua and Serere, and WC48A was the most adapted to Makerere University Agricultural Research Institute, Kabanyolo (MUARIK). There is potential of finding resistance sources in the cultivars tested. Key Words: GGE biplot, Megalurothrips sjostedti, Vigna unguiculata
Euphytica, 2021
Flower bud thrips is one of the most destructive insect pests of cowpea in sub-Saharan Africa. Information on genetic variability among cowpea germplasm and interrelationships among traits under thrips infestation would facilitate the development of resistant varieties. The objectives of the study were to assess genetic variability for thrips resistance, estimate heritability of yield and other traits and investigate inter-trait relationships under thrips infestation. One hundred and fifty-six cowpea lines, including one resistant and one susceptible check, were screened for resistance under natural infestation at two locations in Nigeria, in 2016. Test lines were scored for thrips damage weekly for three consecutive weeks, after removal of spreader plants, to obtain damage scores (DS) 1, 2 and 3 while data were collected on agronomic traits. The data were subjected to analysis of variance from which genetic components of the phenotypic variance were computed. Interrelationships amo...
Euphytica, 2009
Cowpea is an important legume in sub-Saharan Africa where its protein rich grains are consumed. Insect pests constitute a major constraint to cowpea production. Flower bud thrips (FTh) is the first major pest of cowpea at the reproductive stage and if not controlled with insecticides is capable of reducing grain yield significantly. Information on the inheritance of resistance to FTh is required to facilitate breeding of resistant cultivars. The genetics of resistance was studied in crosses of four cowpea lines. Maternal effect was implicated while frequency distributions of the F 2 and backcross generations suggest quantitative inheritance. Additive, dominance and epistatic gene effects made large contributions and since improved inbred lines are the desired product, selection should not be too severe in the early generations to allow for desirable gene recombination. This study suggested that some of the genes involved in the control of resistance to FTh are different in TVu1509 and Sanzi. Broad sense heritability ranged from 56% to 73%. Choice of maternal parent in a cross will be critical to the success of resistance breeding.
2017
Cowpea flower bud thrips causes about 80% yield losses in cowpea. Host plant resistance is the most easy and durable solution to the damaging effects caused by this insect. However, resistance to thrips is quantitatively inherited, thus less amenable through conventional breeding. The objective of this study was to identify QTL associated with resistance to cowpea flower bud thrips in a bid to facilitate the improvement of cowpea resistance to thrips. A mapping population consisting of 150 F2 plants derived from cross between the highly resistant SANZI (female) and the highly susceptible VYA (male) was screened under artificial infestation in the screen house. Thrips damage scores were used as the parameter for resistance. A total of 232 polymorphic Single Nucleotide Polymorphism (SNP) markers were used for genotyping of F2 and the parents. Three significant QTLs for thrips resistance Fthp28, Fthp87 and Fthp129were detected on chromosomes 2, 4 and 6 accounting for 24.5, 12.2 and 6.5...
Screening of 25 cowpea genotypes for resistance to Megalurothrips sjostedti Trybom in southern Ghana
LEGUME RESEARCH - AN INTERNATIONAL JOURNAL
In sub-Saharan Africa, Megalurothrips sjostedti Trybom are the most destructive insect pest of cowpea. It causes approximately 100% reduction in cowpea yield. Synthetic insecticides are widely used in controlling this pest, however, health and environmental hazards are another challenge. This study sought to evaluate 25 cowpea genotypes from Ghana, Mali, Nigeria, Niger, Burkina Faso, Togo and South-Sudan for resistance to this pest under field screening using a 5 by 5 alpha lattice design with 2 checks at University of Ghana farms. The results revealed Laduni 1B as resistant, 20 moderately resistant and 4 susceptible genotypes were also identified in this study. In the determination of correlated and non-correlated variables, ten traits were reported important to the resistance of cowpea genotypes to flower bud thrips. The genotypes with resistance could be used to introgress the resistant trait into other preferred but susceptible cowpea varieties.
Inheritance of cowpea resistance to flower thrips in Uganda germplasm
Journal of Plant Breeding and Crop Science
Flower thrips [Megalurothrips sjostedti (Trybom)] is the most damaging insect pest on cowpea. However, information regarding the nature of gene action governing the inheritance of resistance to thrips is not available for cowpea genotypes in Uganda. This study was carried out to determine the inheritance pattern of cowpea resistance to flower thrips. Five resistant cowpea genotypes and three susceptible genotypes were crossed in full diallel mating design. F2 progenies were evaluated along with the parents in alpha lattice design with two replications under natural thrips infestation at Kabanyolo, Arua and Serere in Uganda. Combining ability analysis was performed using method one and model one of diallel analysis. The results showed that the environmental effects were highly significant (P<0.001). Additive, dominance and epistasis effects had major contributions. The broad sense heritability varied from 18 to 42% for thrips damage scores and from 0 to 6% for thrips counts. The estimates of narrow sense heritability were low for thrips damage score (2 to 18%) and thrips counts (0 to 9%). Genotypes TVU-1471 and TVU-1509 were identified as good transmitters of resistance to flower thrips. Crosses TVU-1509 x NE5, TVU-473 x Sanzi, TVU-123 x Sanzi, TVU-123 x TVU-473, and TVU-473 x TVU-1509 presented significant (P<0.05) and negative SCA effects for thrips damage scores and thrips counts and would be the most useful in breeding as some of their progenies would have high resistance to flower thrips. This study provides the basis of an efficient breeding program of cowpea for flower thrips resistance.
African Journal of Biotechnology, 2008
The first major insect pest of cowpea at reproductive stage is the flower bud thrips (FTh), which, if not controlled, is capable of causing significant grain yield reduction. Breeding for resistance to FTh in cowpea has been hindered by the quantitative nature of the resistance, and the breakdown of resistance under high insect infestation. The purpose of this study was to use molecular markers to identify genetic loci associated with the expression of resistance to FTh. A set of 92 recombinant inbred lines (RILs) was generated from a cross between susceptible and resistant lines. One hundred and thirty nine markers [134 Amplified Fragment Length Polymorphism (AFLP) and 5 cowpea derived microsatellites] were used to construct a linkage map using this set of RILs. The linkage map spans 1620 cM of the cowpea genome and markers were distributed in 11 linkage groups. Average distance between adjacent markers was 9.6 cM. There were significant associations between 23 DNA markers and resi...
Crop Protection, 2004
The effect of host plant resistance on growth and developmental parameters of the bean flower thrips Megalurothrips sjostedti Trybom was determined on nine cowpea (Vigna unguiculata {L.}Walp.) cultivars under laboratory conditions. Newly emerged adults M. sjostedti were confined on peduncles with floral buds of the different cowpea cultivars. M. sjostedti suffered 100% preimaginal mortality on cowpea lines Moussa local, TVu1509, TVx3236, Sewe and Sanzibanili. Antibiosis is believed to be the mechanism of resistance operating in these cultivars. On KVx404-8-1, M. sjostedti had a prolonged developmental period though not significantly different from Vita 7, the susceptible check at Po0:01: IT91K-180 supported the development and survival of M. sjostedti with the suitability index (growth index) not significantly different from the susceptible check (Vita 7