Research Papers

Permanent URI for this communityhttps://repository.tmu.ac.ke/handle/123456789/169

The research papers are organized by faculties

Browse

Subject: search.filters.subject.Western Kenya

Search Results

Now showing 1 - 2 of 2
  • No Thumbnail Available
    Item
    Reduced bio-efficacy of aged PermaNet® 3.0 Nets against local pyrethroid-resistant Anopheles arabiensis in Western Kenya
    (Frontiers in Tropical Diseases, 2026-01-30) Machani, Maxwell G.; Zhou, Guofa; Oyweri, Job; Nzioki, Irene; Githure, John; Atieli, Harrysone; Wang, Chloe; Zhong, Daibin; Lee, Ming-Chieh; Afrane, Yaw A.; Yan, Guiyun
    Background: Long-lasting insecticidal nets (LLINs) are central to malaria control and designed to protect for up to three years; however, increasing pyrethroid resistance undermines their effectiveness. Piperonyl butoxide (PBO) LLINs, designed to enhance pyrethroid efficacy, are recommended in high-resistance areas, yet their long-term operational bio-efficacy remains unclear. This study evaluated the killing efficacy of PBO LLINs over three years of field use compared to standard LLINs and monitored insecticide resistance in local Anopheles gambiae s.l. populations. Methods: During a trial in Muhoroni, western Kenya (2021–2024), standard and PBO LLINs were collected at 6, 18, and 36 months of use. Residual bio-efficacy was assessed using WHO cone bioassays against a susceptible Anopheles gambiae s.s. Kisumu strain and field An. gambiae s.l. populations. WHO tube and bottle assays determined insecticide resistance, while synergist assay assessed metabolic resistance. Quantitative polymerase chain reaction detected target-site mutations (kdr-1014 F/S and Ace-1 G119S). Results: Molecular identification confirmed all An. gambiae s.l. were Anopheles arabiensis, showing increasing pyrethroid resistance, with deltamethrin mortality declining from 96.3% (2021) to 22.7% (2024) while remaining susceptible to pirimiphos-methyl and clothianidin. PBO pre-exposure restored deltamethrin mortality from 22.7% to 98.9%. The frequency of 1014F increased from 0.09 to 0.17 and 1014S from 0.04 to 0.06, with no Ace-1 mutations detected. Standard LLINs retained >80% efficacy against the susceptible strain for 18 months but were below threshold against field mosquitoes even when new. PBO LLINs were effective at baseline against field populations but declined sharply, with mortality dropping to 24% by 6 months. Overall, both net types exhibited a marked decline in killing efficacy over time against field mosquitoes, with mortality falling < 20% within six months. Conclusion: Anopheles arabiensis showed increasing pyrethroid resistance, driven largely by metabolic mechanisms. Standard LLINs showed suboptimal killing efficacy against field populations, while PBO LLINs achieved high baseline efficacy but declined significantly by six months. These findings indicate that PBO LLINs can improve protection against resistant vectors but may be insufficient in high-resistance areas, underscoring the need for alternative non-pyrethroid interventions, strategic deployment, and revised LLIN re-distribution cycles aligned with their functional lifespan.
  • No Thumbnail Available
    Item
    Drivers of Organic Fertiliser Adoption and Use Intensity Among Smallholder Maize Farmers in Lake Victoria Region, Western Kenya
    (Open access publication ., 2025-07-16) Rosebell Achieng Owuor; Alphonce Juma Odondo; Caleb Ollweny; Mathews Dida
    Smallholder farmers account for about 75% of maize production in Kenya. The current average on farm productivity is 1.43 ton/ha against the potential of 6 ton/ha. In Western Kenya, low soil organic carbon is one of the contributors to the low maize productivity. Studies have shown that organic fertilizers contribute towards increase in soil productivity. However, there is paucity of information on the relationship between drivers of organic fertilizers adoption and use intensity among the farmers, which the study seeks to address. A total of 358 farmers were interviewed in the 2020/21 growing seasons. Heckman’s two-stage model was estimated. The results demonstrate that age, education, gender, soil quality perception and access to supportive resources are pivotal in shaping organic farming decisions. There is need for targeted extension services to less educated and older farmers. Off-farm income generation should be encouraged. Integrated soil fertility management approaches that address nutrient replenishment and soil erosion control is necessary, and there is need to promote mechanization or subsidization of organic fertilizer application on larger farms as this may help overcome labour constraints and improve organic fertilizer adoption on a broader scale. The results may be a source of literature for subsequent studies in related fields.