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  1. Home
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Browsing by Author "Kyamanywa, S."

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    Farmer-participatory Evaluation of Cowpea integrated Pest Management (IPM) Technologies in Eastern Uganda
    (Crop Protection, 2003) Nabirye, J.; Nampala, P.; Ogenga-Latigo, M.W.; Kyamanywa, S.; Odeke, V.; Adipala, E.
    A three-season study was conducted with the goal of verifying integrated pest management (IPM) technologies developed at Makerere University for management of cowpea field pests. Ten IPM-field schools with 10–20 farmers were run for three consecutive seasons of 2000 A (first rains), 2000 B (second rains), and 2001 A. Each school evaluated seven treatments that included farmers’ practices; cowpea monoculture and cowpea/sorghum intercrop mixtures, and five varying insecticide spray regimes. The key insect pests targeted by the sprays included aphids, Aphis craccivora Koch, flower thrips, Megalurothrips sjostedi Trybom, the legume pod borer, Maruca vitrata Fabricius (formerly M. testularis Geyer), and a range of pod sucking bugs (i.e., Nezera viridula Linnaeus, Clavigralla tomentosicollis Stal., Riptortus dentipes Fab.). The experiment was a randomized complete block design with farms (i.e., field schools) as replicates. Results indicated that combining cultural practices and spraying once each at budding, flowering, and podding stages was more effective and profitable than spraying cowpea weekly throughout the growing season. An IPM practice which combined early planting, close spacing cowpea (30×20cm2), and three insecticide applications once each at budding, flowering and podding stages, had the highest yields of 791kg/ha with a 51% yield gain over the farmers’ traditional practices. Farmer evaluation over the three seasons revealed that this practice was most preferred by farmers, with a farmer preference of 46.4%, 57.1%, 71.4%, and 89.3% at planting, vegetative, flowering and harvesting evaluation stages, respectively.
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    Genetic Basis of Maize Resistance to Multiple Insect Pests: Integrated Genome-Wide Comparative Mapping and Candidate Gene Prioritization
    (Genes, 2020) Badji, A.; Kwemoi, D. B.; Machida, L.; Okii, D.; Mwila, N.; Agbahoungba, S.; Kumi, F.; Ibanda, A.; Bararyenya, A.; Solemanegy, M.; Odong, T.; Wasswa, P.; Otim, M.; Asea, G.; Ochwo-Ssemakula, M.; Talwana, H.; Kyamanywa, S.; Rubaihayo, P.
    Several species of herbivores feed on maize in field and storage setups, making the development of multiple insect resistance a critical breeding target. In this study, an association mapping panel of 341 tropical maize lines was evaluated in three field environments for resistance to fall armyworm (FAW), whilst bulked grains were subjected to a maize weevil (MW) bioassay and genotyped with Diversity Array Technology’s single nucleotide polymorphisms (SNPs) markers. A multi-locus genome-wide association study (GWAS) revealed 62 quantitative trait nucleotides (QTNs) associated with FAW and MW resistance traits on all 10 maize chromosomes, of which, 47 and 31 were discovered at stringent Bonferroni genome-wide significance levels of 0.05 and 0.01, respectively, and located within or close to multiple insect resistance genomic regions (MIRGRs) concerning FAW, SB, and MW. Sixteen QTNs influenced multiple traits, of which, six were associated with resistance to both FAWandMW, suggesting a pleiotropic genetic control. Functional prioritization of candidate genes (CGs) located within 10–30 kb of the QTNs revealed 64 putative GWAS-based CGs (GbCGs) showing evidence of involvement in plant defense mechanisms. Only one GbCG was associated with each of the five of the six combined resistance QTNs, thus reinforcing the pleiotropy hypothesis. In addition, through in silico co-functional network inferences, an additional 107 network-based CGs (NbCGs), biologically connected to the 64 GbCGs, and di erentially expressed under biotic or abiotic stress, were revealed within MIRGRs. The provided multiple insect resistance physical map should contribute to the development of combined insect resistance in maize.
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    Genomic Prediction of Tropical Maize Resistance to Fall Armyworm and Weevils: Genomic Selection Should Focus on Effective Training Set Determination
    (ResearchGate, 2020) Badji, A.; Machida, L.; Kwemoi, D. B.; Kumi, F.; Okii, D.; Mwila, N.; Agbahoungba, S.; Ibanda, A.; Bararyenya, A.; Nghituwamhata, S. N.; Odong, T.; Wasswa, P.; Otim, M.; Ochwo-Ssemakula, M.; Talwana, H.; Asea, G.; Kyamanywa, S.; Rubaihayo, P.
    Genomic selection (GS) can accelerate variety release by shortening variety development phase when factors that influence prediction accuracies (PA) of genomic prediction (GP) models such as training set (TS) size and relationship with the breeding set (BS) are optimized beforehand. In this study, PAs for the resistance to fall armyworm (FAW) and maize weevil (MW) in a diverse tropical maize panel composed of 341 double haploid and inbred lines were estimated. Both phenotypic best linear unbiased predictors (BLUPs) and estimators (BLUEs) were predicted using 17 parametric, semi-parametric, and nonparametric algorithms with a 10-fold and 5 repetitions cross-validation strategy. n. For both MW and FAW resistance datasets with an RBTS of 37%, PAs achieved with BLUPs were at least as twice as higher than those realized with BLUEs. The PAs achieved with BLUPs for MW resistance traits: grain weight loss (GWL), adult progeny emergence (AP), and number of affected kernels (AK) varied from 0.66 to 0.82. The PAs were also high for FAW resistance RBTS datasets, varying from 0.694 to 0.714 (for RBTS of 37%) to 0.843 to 0.844 (for RBTS of 85%). The PAs for FAW resistance with PBTS were generally high varying from 0.83 to 0.86, except for one dataset that had PAs ranging from 0.11 to 0.75. GP models showed generally similar predictive abilities for each trait while the TS designation was determinant. There was a highly positive correlation (R=0.92***) between TS size and PAs for the RBTS approach while, for the PBTS, these parameters were highly negatively correlated (R=-0.44***), indicating the importance of the degree of kinship between the TS and the BS with the smallest TS (31%) achieving the highest PAs (0.86). This study paves the way towards the use of GS for maize resistance to insect pests in sub-Saharan Africa.
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    Influence of socioeconomic, product and service quality attributes on certified sweetpotato seed use in Uganda
    (African Journals Online (AJOL), 2024-08-07) Musoke, C.; Kyazze, F.B.; Kibwika, P.; Kyamanywa, S.; Mukasa, S.B.
    The sweetpotato (Ipomoea batatas (L) Lam) seed system in Uganda is transiting from an informal to a formal setting, by integrating the use of certified sweetpotato seed (CSS) in the production system. Use of CSS enhances productivity by controlling the spread of the sweetpotato virus disease (SPVD) and seed degeneration. However, owing to the limited understanding of product and service quality attributes by farmers, the sustained use of CSS has remained dismal. The objective of this study was to investigate the contribution of farmer socioeconomic characteristics; product and service quality attributes to sustained use of CSS in Uganda. A total of 289 sweetpotato farmers from Central (Mpigi district) and Northern (Omoro district) Uganda, representing low and high SPVD prevalence zones, respectively, were interviewed to obtain information on product attributes (acceptability, accessibility, affordability and awareness) and service attributes (reliability, tangibility, assurance, responsiveness and empathy). Data were subjected to a Double Hurdle analysis. Results revealed that users of CSS scored more for product and service quality attributes, than their non-user counterparts. There was a highly positive correlation between use of CSS and education level in central; but a modestly positive in northern Uganda. Reliability (b = 0.289, 12.612) positively drove the use and extent of use of CSS; while for tangibility (b = -0.302, -11.742), the converse was true. Also, acceptability (b = 0.469, 22.048) increased the use and extent of use of CSS; yet accessibility increased only the use in both locations (b = 0.268). Thus, efforts to scale-out CSS use in the study areas should focus more on affordability, awareness, assurance and empathy based on location; putting into consideration education level and group membership differences.
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    Insecticide application to reduce pest infestation and damage on cowpea in Uganda
    (African Plant Protection, 1998-08-05) Omongo, C.A.; Adipala, E.; Ogenga-Latigo, M.W.; Kyamanywa, S.
    Field assessments were carried out in seven districts of eastern and northern Uganda to establish pest infestation of cowpea (Vigna unguiculata) and the extent of insecticide usage to control these pests. More than 60 % of the farmers in eastern Uganda applied insecticides to control cowpea pests whereas no farmers in the northern region used chemieels for this purpose. The extent of pest infestation at different crop growth stages appeared to influence pesticide application, with mostlarmers spraying during the vegetative (30 %) and flowering (50 %) stages. and only a few at podding (10 %). There was evidence 01 ineffective/uneconomical use of insecticides. On-farm trials indicated that insecticide protection at all crop growth stages gave the best control. leading to yield gains 01 more than 50 %. Spraying during vegetative and flowering stages was also effective. giving yield gains of about 40 %. A three-spray programme (at vegetative growth. flowering and podding) was most profitable in the short rainy season at Serere (marginal return = 6.08) and second best in the long rainy season at Kabanyolo (marginal return = 4.35).
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    Maize resistance to stem borers and storage pests: The need for new genetic and functional genomics approaches in future research
    (African Journal of Rural Development, 2017) Badji, A.; Otim, M.; Machida, L.; Odong, T.L.; Kyamanywa, S.; Rubaihayo, P.
    Insect pests are primary constraints in maize (Zea mays) production in many places in sub-Saharan Africa. Stem borers and storage pests are responsible for severe yield losses and health hazards due to mycotoxin contamination. Integrated pest management (IPM) strategies have moved from control methods and transgenic resistance to recognizing the necessity of host plant resistance (HPR) especially in the context of an ever changing climate and its forecasted negative consequences. For that, a wealth of scientific knowledge has been generated over the years although the goals are far to be reached. Here, we first review current literature on maize resistance mechanisms as regards to insect herbivory. We show that there are numerous insect species that feed on maize before narrowing down to stem borers and storage pests. We also look at the basis of maize resistance in terms of its biochemical components and analyze the progress of genetic studies in terms of QTL mapping and trait genes identification. Finally, we highlight the usefulness of new genetic and functional genomic approaches in underpinning the genetic basis of maize resistance to insect pests in general and particularly stem borers and storage pests.
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    Novel source of sorghum tolerance to the African stem borer, Busseola fusca
    (African Journal of Plant Science, 2012-08-16) Muturi, P. W.; Rubaihayo, P.; Mgonja, M.; Kyamanywa, S.; Hash, C. T.
    Sorghum (Sorghum bicolor) is an important cereal food crop in semi-arid tropics, but its productivity is curtailed mainly by insect pests and diseases. The African stem borer, Busseola fusca Fuller (Lepidopteran: Noctuidae), is among the most injurious pests of sorghum in sub-Saharan Africa and is responsible for >15% sorghum grain yield losses. Sorghum from India with records of stem borer invasion could provide supplementary and novel resources of tolerance to this pest. Utilization of tolerant varieties in combination with other methods of control is likely to offer a sustainable strategy for B. fusca management in sorghum production. The objective of this study was to evaluate several local and exotic sorghum genotypes for tolerance to B. fusca. Genotype Swarna from India which is known to be susceptible to Chilo partellus was used as a susceptible check. There is limited information regarding tolerant/resistant sorghum to B. fusca. Seven commercial cultivars and 20 introductions from India were evaluated for B. fusca tolerance at Kabete, in central province of Kenya, during long and short rainy seasons in 2010. Selection index were based on leaf damage, dead hearts, exit holes and stem tunneling. The following genotypes named ICSA 467, ICSA 473, MACIA and ICSB 464 were found to be the most tolerant to B. fusca. These tolerant genotypes, can be used as novel sources of tolerance, and could be introgressed into the local common varieties since they are well adapted to the local environment.
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    Oviposition preference and offspring performance of Crocidolomia pavonana (Lepidoptera: Pyralidae) on different host plants
    (Journal of Applied Entomology, 2010) Karungi, J.; Lubanga, U. K.; Kyamanywa, S.; Ekbom, B.
    The cabbage head caterpillar Crocidolomia pavonana (Fabricius) (Lepidoptera: Pyralidae) is an increasingly devastating pest on white cabbage (Brassica oleracea var. capitata) in Uganda. Screen house and field trials were used to assess oviposition preference and offspring performance of C. pavonana on six hosts in the genus Brassica: kale (B. oleracea var. acephala), cauliflower (B. oleracea var. botrytis), broccoli (B. oleracea var. italica), Chinese cabbage (B. campestris spp. pekinensis), Indian mustard (B. juncea (L.) Czern.) and white cabbage (B. oleracea var. capitata). To assess oviposition preference, the hosts were offered to C. pavonana in multiple-choice (all six); two-choice (cabbage with each of the other hosts) or cabbage-only situations. After specified oviposition periods, egg numbers on individual plants were recorded. To determine C. pavonana offspring performance on the six hosts, whole plants were placed in individual cages, where larvae were monitored for development time, pupal weight and foliage consumption. Results of the choice tests indicated that C. pavonana preferred Chinese cabbage and broccoli for oviposition. In two-choice arrangements, all the tested host plants were able to greatly reduce oviposition on white cabbage (69–100%) when compared with the monocrop. Chinese cabbage was the most suitable host with regard to C. pavonana offspring performance as demonstrated by the shortest development time and highest pupal weight. Chinese cabbage and broccoli can be used as traps for the pest but the resulting larvae should be destroyed regularly to prevent accumulation in the system.
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    Portable PCR field-based detection of sweetpotato viruses
    (African Crop Science Journal, 2020) Ssengo, J.; Wasswa, P.; Mukasa, S.B.; Okiror, A.; Kyamanywa, S.
    Sweetpotato (Ipomoea batatas Lam.) production is greatly constrained by viral infections, especially Sweet potato feathery mottle virus and Sweet potato chlorotic stunt virus that synergistically cause a severe sweetpotato virus disease. The impact of viruses is aggravated by the vegetative nature of the crop and inaccessibility to dependable diagnostic tools in rural areas where sweetpotato production is done. This makes it hard for seed inspectors to perform quality checks prior to use of vines for planting. The objective of this study was to develop a procedure that allows for detection of sweetpotato viruses on-site. This involved modification of the Lodhi et al. (1994) nucleic acid extraction procedure, by omitting some of the laboratory specific steps and varying the incubation time in liquid nitrogen, instead of the freezer. Incubation in liquid nitrogen for only 1.5 hours yielded as high quality RNA compared to that of the original protocol, when incubation was done at 4°C overnight in a freezer. Reverse transcriptase (RT) was run using a portable miniPCR thermocycler; and the resulting cDNA was amplified using this miniPCR machine instead of using a laboratory stationed conventional PCR thermocycler. The cDNA was efficiently amplified and amplicons were similar to those obtained with the original extraction protocol and subsequent amplification by the conventional RT-PCR. Our protocol reduced extraction time from about 16 hours for the original protocol, to about 2 hours and 45 minutes. If this tool is utilised by the crop protection departments, we believe it will contribute greatly towards sustainable sweetpotato production through making timely recommendations.
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    Prevalence of viruses infecting cowpea in Uganda and their molecular detection
    (African Journal of Biotechnology, 2012-01-26) Amayo, R.; Arinaitwe, A. B.; Mukasa, S. B.; Kyamanywa, S.; Rubaihayo, P. R.; Edema, R.
    The main areas for cowpea cultivation in Uganda were surveyed in June and October 2006 for viruses affecting the crop. Seed and leaf samples from symptomatic and asymptomatic plants were collected from farmers’ fields and analysed for infecting viruses using double antibody sandwich enzyme-linked immunosorbent assay (DAS-ELISA). The viruses detected in the leaf and seed samples were: cucumber mosaic cucumovirus (CMV), cowpea mild mottle calarvirus (CPMMV), cowpea mottle carmovirus (CPMoV), Cowpea chlorotic mottle bromovirus (CCMV), Cowpea yellow mosaic comovirus (CYMV), cowpea severe mosaic comovirus (CPSMV), cowpea aphid-borne mosaic potyvirus (CABMV) and Southern bean mosaic sobemovirus (SBMV). CPMV was detected only in leaf samples. CMV and CABMV were later confirmed using reverse transcription polymerase chain reaction (RT-PCR). Of the viruses detected in leaf samples, 53.26% occurred as single infections, 24.46% dual and 22.28% multiple infections. Similarly, analysis of seed samples revealed infection of 40.6, 34.6 and 24.8% for single, dual and multiple infections, respectively. Multiple virus infections were associated with more disease severity and higher yield losses. The seed transmission levels of 23.0, 20.3 and 16.4% were recorded for CMV, CPMMV and CABMV, respectively. This study identified six more viruses in addition to what was previously reported in the country, of which eight were seed-borne. This necessitates the need for the production and use of virus-free seeds, development of virus resistant genotypes and adoption of efficient seed certification systems.
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    Relating shading levels and distance from natural vegetation with hemipteran pests and predators occurrence on coffee
    (Journal of applied entomology, 2015) Karungi, J.; Nambi, N.; Ijala, A. R.; Jonsson, M.; Kyamanywa, S.; Ekbom, B.
    The study was carried out to determine the effect of shading levels and/ or distance from the natural alpine vegetation (NAV) on the occurrence of two insect functional groups: hemipteran herbivores and generalist predators in farmers’ coffee fields in the Mt. Elgon region of Uganda. Three distance categories from the NAV, that is (i) 0–250 m; (ii) 250– 1000 m and (iii) 1000–1500 m, were used to demarcate farms in the first stage of selection, and within each distance category, three levels of shading, that is (i) no shade, (ii) moderate shade and (iii) full shade, were used for final selection of coffee farms for the study. A total of 90 individually owned coffee fields were studied; 30 for each distance category, of which 10 represented each shading level. In two separate rounds, inventories of scale insects (Coccus spp.), antestia bugs (Antestiopsis spp.), root mealybugs (Planococcus spp.) and aphids (Toxoptera aurantii) on coffee plants were made for the hemipteran herbivores, whereas ants (Formicidae) and spiders (Araneae) were recorded for the predatory taxa. The results showed that the interaction between distance from the NAV and shading level consistently influenced the occurrence of the insects in both functional groups. For scale insects, root mealybugs and ants, it was closest to the NAV that shading-level effects were most discernible and generally limiting. To the contrary, the occurrence of aphids and spiders increased with the increase in the level of shading for plants furthest from the NAV. These results indicate that if inclusion of shade trees is to be a strategy in ecological pest management, the level of shading should be determined basing on the insect taxa as well as other pertinent factors in the landscape.

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