Browsing by Author "Mayamba, Alex"

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    Factors influencing the distribution and abundance of small rodent pest species in agricultural landscapes in Eastern Uganda
    (Journal of Vertebrate Biology, 2020) Mayamba, Alex; Byamungu, Robert M.; Vanden Broecke, Bram; Leirs, Herwig; Hieronimo, Proches; Nakiyemba, Alice; Isabirye, Moses; Kifumba, David; Kimaro, Didas N.; Mdangi, Mshaka E.; Mulungu, Loth S.
    Small rodents are increasingly gaining importance as agricultural pests, with their distribution and abundance known to vary across landscapes. This study aimed at identifying ecological factors in the landscape that may influence small rodent distribution and abundance across agricultural landscapes in Uganda. This information may be used to inform the development of adaptive control measures for small rodent pests. Small rodent trapping surveys were conducted in three agro-ecosystem landscapes: Butaleja, Mayuge and Bulambuli districts in Eastern Uganda between November 2017 to June 2018 covering both dry and wet seasons. Data on small rodent abundance and richness, vegetation characteristics, land use/cover characteristics, farm management practices and soil characteristics were collected from quadrats. Additionally, Geographic Information System and remote sensing were used to determine vegetation characteristics (Normalized Difference Vegetation Index – NDVI) and land use/cover from satellite images. Our results showed that crop field state (including hygiene, crop type and growth stage) is the most important variable with an overall relative importance of 34.4% prediction value for the abundance of Mastomys natalensis across the landscape studied. In terms of number of species encountered (species richness), results showed field crop status scoring highest with an overall relative importance of 39.8% at predicting small rodent species richness. Second in importance for overall rodent abundance was percentage composition soil silt particles with 15.6% and 18.1% for species richness and abundance respectively. Our findings have important implications for small rodent management, where land use characteristics, especially field crop state, is a critical factor as different conditions tend to affect rodent abundances differently. The study thus recommends that control efforts should be planned to consider field crop state; i.e. field hygiene where fields should be kept free of weeds to eliminate potential rodent breeding/habitation sites thus lowering rates of reproduction and population increase.
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    Fitness of the Pestiferous Small Rodent Mastomys Natalensis in an Agroecosystem in Mayuge District, Lake Victoria Crescent, Uganda
    (Mammalia, 2020) Mayamba, Alex; Isabirye, Brian E.; Byamungu, Robert M.; Nakiyemba, Alice; Isabirye, Moses
    A 2.5-year study was conducted to understand the fitness of Mastomys natalensis in an agroecosystem in relationship with environmental predictors. The study was conducted in Mayuge district, in the Lake Victoria Crescent zone in Eastern Uganda. Fitness was measured in terms of survival, maturation and capture probability and estimated using multi-event capture-recapture models. Survival rates were higher after high rainfall in the previous month and increased with increasing population density of the animals. Maturation rate, on the other hand, showed no significant association with any predictor variables, while capture probability was significantly associated with sex of the animals, with higher capture probability for males. The results demonstrate that the fitness of M. natalensis in an agroecosystem is dependent on rainfall, sex and current population density. The aforementioned results were associated with increasing vegetation which provides cover for animal nesting and abundant food for the animals during rainfall periods and thus increased survival, high mobility in males in search for mates thus exposing animals to high chances of being captured and increased prey saturation at high population density resulting in high animal survival. These results have important implications for the timing of management strategies, i.e. control efforts should be enforced during the rainfall seasons to prevent high population buildup in the succeeding seasons.
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    Integrated Management of Fruit Flies – Case Studies from Uganda
    (Springer, Cham., 2016) Isabirye, Brian E.; Nankinga, Caroline K.; Mayamba, Alex; Akol, Anne M.; Rwomushana, Ivan
    Fruit flies (Diptera: Tephritidae) pose a threat to commercialisation of the horticulture industry in Uganda. They impair the quality and quantity of fruits produced, and limit access to lucrative regional and global markets. Here we explore past and present efforts, and future plans for research and management, of fruit flies in Uganda. Early research geared towards collection and identification of fruit flies recognised the pest status of many species and highlighted the need for establishing sustainable management strategies. Subsequently large-scale research initiatives have substantially increased knowledge on the biology and ecology of fruit flies in Uganda. Based on these studies, integrated pest management (IPM) options for fruit flies have been designed and piloted. Amongst the most promising options are the Male Annihilation Technique (MAT) in combination with the Bait Annihilation Technique (BAT) or Protein Food Bait (PFB) and Orchard Sanitation (OS). Fruit bagging is also receiving attention. It is now recommended that IPM options are combined and scaled up in an area-wide approach. The government of Uganda has demonstrated genuine commitment to eradication of fruit flies through three key project initiatives: (i) Gaining insight into the ecological and physiological factors influencing fruit fly populations and infestation rates in mango-growing regions of Uganda (NARO-MSI); (ii) Equipping key technical personnel at local and district levels with knowledge on identification and management of key fruit fly pest species (NAADS); (iii) Promotion and adoption of IPM practices for fruit fly management (NARO-ATAAS). These initiatives will ensure the long-term sustainability of management options.
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    Population and Breeding Patterns of the Pest Rodent: Mastomys Natalensis in a Maize Dominated Agroecosystem in Lake Victoria Crescent Zone, Eastern Uganda
    (African Zoology, 2021) Mayamba, Alex; Byamungu, Robert Modest; Isabirye, Moses; Makundi, Rhodes H.; Kimaro, Didas N .; Massawe, Apia W.; Kifumba, David; Nakiyemba, Alice; Mdangi, Mshaka E.; Isabirye, Brian E.; Mulungu, Loth S.
    Multimammate mice (Mastomys natalensis) are a key rodent pest species to cereal crop production in Sub-Saharan Africa. This study aimed at generating information on the population fluctuation and breeding patterns of M. natalensis in a maize dominated agro-ecosystem in the Mayuge district, Eastern Uganda. The area is characterised by a bimodal rainfall pattern with rains in the periods March to May and August to November. A Capture–Mark–Recapture study was established in cultivated and fallow field habitats with, in each habitat, two plots of 60 m by 60 m with 49 evenly spaced trapping points. Trapping was conducted monthly for three consecutive nights, and the study extended from January 2016 to June 2018. A Generalised Linear Mixed Model analysis showed significantly higher population density estimates (β = 0.69, p<0.0001) in fallow land compared to cultivated fields, and also significantly higher density estimates( β = 0.75, p = 0.006) in the first wet season and lowest in the first dry season. The percentage breeding females differed significantly across months (χ 2 = 27.05, df = 11, p = 0.003) and seasons (χ 2 = 17.64, p = 0.0003). Breeding females occurred throughout all the months of trapping, but with significantly higher percentages in the months of March to July (i.e. first wet season extending to second dry season) and generally lowest in the first dry months (i.e. January and February in 2017, and February 2018). The results of this study have important consequences for the timing of control efforts, and recommends that control should be initiated during the dry seasons prior to wet seasons to counteract potential damaging population build up in later wet seasons when crop planting is expected.
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    Seasonal Population Fluctuations of Bactrocera Invadens (Diptera: Tephritidae) in Relation to Mango Phenology in the Lake Victoria Crescent, Uganda
    (Fruits, 2014) Mayamba, Alex; Nankinga, Caroline Kukiriza; Isabirye, Brian; Akol, Anne Margaret
    Timing of management practices requires an understanding of pest population dynamics in given cropping systems. Our study was designed to establish the population trends of B. invadens in mango orchards and to determine if population fluctuations were reflected in fruit infestation levels during changes in mango phenology. Bactrocera invadens flies were trapped weekly from February 2011 to November 2012, using methyl eugenol and DDVP (dichlorvos) insecticidal strips. Trapping was done in three mango orchards in the Luweero district of Uganda’s Lake Victoria Crescent. Mango fruit samples were incubated for the retrieval of puparia to calculate positivity (proportion of fruits infested) and fruit infestation indices (number of puparia per kg of fruit) for each stage of fruit maturity. Results. Mean trap catches of adult B. invadens varied significantly over the months (range : ~11 flies per trap per day (FTD) to over 590 FTD; P £ 0.0001). During each year, infestations peaked during June-July and January-February. Trap catches were higher in the major fruiting season compared with the minor fruiting season and were the highest when mango was at the physiological maturity and ripe stages. Fruit infestation and positivity were highest for fruit at the physiological maturity and ripe stages and lowest at the fruit set stage. Our findings show that B. invadens is present year-round and all stages of mango fruit development are susceptible to attack. Thus, control measures should be implemented throughout the year and preferably started at fruit set to lessen fruit fly population build-up and damage to fruits.
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    Species Composition and Community Structure of Small Pest Rodents (Muridae) in Cultivated and Fallow Fields in Maize‐ Growing Areas in Mayuge District, Eastern Uganda
    (Ecology and evolution,, 2019) Mayamba, Alex; Byamungu, Robert M.; Makundi, Rhodes H.; Kimaro, Didas N.; Isabirye, Moses; Massawe, Apia W.; Kifumba, David; Nakiyemba, Alice; Isabirye, Brian E.; Mulungu, Loth S.
    Pest rodents remain key biotic constraints to cereal crops production in the East African region where they occur, especially in seasons of outbreaks. Despite that, Uganda has scant information on rodents as crop pests to guide effective management strategies. A capture–mark–recapture (CMR) technique was employed to study the ecology of small rodents, specifically to establish the species composition and community structure in a maize-based agro ecosystem. Trapping of small rodents was conducted in permanent fallow land and cultivated fields, with each category replicated twice making four study grids. At each field, a 60 × 60 m grid was measured and marked with permanent trapping points spaced at 10 × 10 m, making a total of 49 trapping points/grids. Trapping was conducted monthly at 4-week interval for three consecutive days for two and half years using Sherman live traps. Eleven identified small rodent species and one insectivorous small mammal were recorded with Mastomys natalensis being the most dominant species (over 60.7%). Other species were Mus triton (16.1%), Aethomys hendei (6.7%), Lemniscomys zebra (5.2%), Lophuromys sikapusi (4.8%), Arvicanthis niloticus (0.9%), Gerbilliscus kempi (0.1%), Graphiurus murinus (0.1%), Steatomys parvus (0.1%), Dasymys incomtus (0.1%), and Grammomys dolichurus (0.1%). Spatially, species richness differed significantly (p = 0.0001) between the studied field habitats with significantly higher richness in fallow land compared with cultivated fields. Temporally, total species richness and abundance showed a significant interaction effect over the months, years, and fields of trapping with significantly (p = 0.001) higher abundances during months of wet seasons and in the first and third year of trapping. In terms of community structure, higher species diversity associated more with fallow field habitats but also with certain rare species found only in cultivated fields. Synthesis and applications. Based on these findings, management strategies can be designed to target the key pest species and the most vulnerable habitats thus reducing the impact they can inflict on field crops.