Biology subjects

Mwangangi, J.

Publications and source records attributed to Mwangangi, J..

4 recordsLinked to original sources

bioRxiv2026

Larval habitat bacteria emit volatile semiochemicals that modulate oviposition site selection in the malaria vector Anopheles gambiae (Diptera: Culicidae)

BackgroundLarval habitat management is increasingly recognized as a complementary strategy for malaria vector control. While bacterial communities are abundant in mosquito breeding sites, their role in shaping oviposition behavior of Anopheles gambiae (Diptera: Culicidae) remains poorly understood. This study evaluated the relative attractiveness or repellency of water infused with bacterial isolates obtained from mosquito larval habitats to gravid Anopheles gambiae. MethodsWe isolated and taxonomically characterized bacteria from 30 larval habitats in coastal Kenya using 16S rRNA sequencing. Thirty-two representative isolates were tested in two-choice oviposition bioassays with gravid An. gambiae s.s., and volatile organic compounds (VOCs) emitted were analyzed by GC-MS. Statistical analyses included Students t-tests, Mann-Whitney U tests, and calculation of the Oviposition Activity Index (OAI). ResultsProteobacteria dominated larval habitats (78%), with frequent genera including Aeromonas, Acinetobacter, Pseudomonas, Enterobacter, and Cronobacter. Most isolates exerted strong deterrent effects, with Aeromonas hydrophila, Enterobacter hormaechei, and Pseudomonas mendocina completely inhibiting oviposition (OAI = -1; 100% repellency). Other isolates such as Neobacillus drentensis and Aeromonas veronii reduced egg deposition by >85%. In contrast, a small subset (Aquitalea pelogenes, Pseudomonas oleovorans, Cronobacter sakazakii) showed weak, non-significant attraction (OAI = 0.15-0.23). GC-MS revealed that highly repellent isolates emitted abundant benzenoids, ketones, phenols, ethers, oxygenated heterocycles, and aldehydes. ConclusionsBacterial volatiles strongly modulate oviposition site selection in An. gambiae, with most isolates acting as potent repellents. These findings highlight microbial VOCs as promising candidates for novel vector control strategies targeting gravid mosquitoes. Limitations include the laboratory-based bioassay design and lack of field validation of VOC activity. Future work should identify specific bioactive compounds and evaluate their efficacy under natural conditions. Research HighlightsO_LIBacteria from mosquito larval habitats influence oviposition of Anopheles gambiae. C_LIO_LISeveral bacterial isolates significantly repel gravid mosquitoes. C_LIO_LIGC-MS analysis revealed VOCs including benzenoids, ketones, phenols, and aldehydes. C_LIO_LIBacterial volatiles show potential for novel mosquito control strategies. C_LI

microbiology↗

bioRxiv2025

Ecological diversity of Anopheles gambiae s.l. and insecticide resistance across refugee camps in Kenya

Malaria remains a major threat during humanitarian crises, necessitating targeted vector control strategies informed by local vector dynamics. Between May and July 2023, we conducted larval surveys in refugee settlements across Dadaab, Kakuma, and Kalobeyei (Kenya), collecting Anopheles larvae. Genotyping of 728 specimens revealed spatial variations in species composition. Overall, Anopheles arabiensis was the dominant species (59%, n=426), followed by Anopheles coluzzii (35%, n=252), and Anopheles rufipes (1%, n=7). In Dadaab, An. arabiensis was overwhelmingly dominant (94%, n=352/374). In contrast, the Kakuma/Kalobeyei complex was characterized by the co-occurrence of An. coluzzii (72%, n=252/350) and An. arabiensis (22%, n=74/350), with An. rufipes exclusively found in Kalobeyei (7%, n=6/89) (Figure 2B). Notably, no members of the Anopheles funestus group or Anopheles stephensi were detected. However, approximately 5% of the larvae across the sites could not be resolved molecularly. High frequencies of the L1014F kdr mutation, a pyrethroid resistance marker, were detected in An. coluzzii (Kakuma: 50%; Kalobeyei: 63%) and An. arabiensis (Kakuma: 10%; Kalobeyei: 30%) populations in Turkana County. Interestingly, no kdr mutations were observed in the An. arabiensis population from Dadaab. These findings highlight significant spatial diversity in vector species composition and resistance profiles, with An. coluzzii emerging as a dominant, pyrethroid-resistant vector in the Kakuma/Kalobeyei complex. The results underscore the urgent need for targeted interventions, including resistance monitoring and alternative insecticide-based strategies, to mitigate malaria transmission risks in fragile, humanitarian settings. Further studies are warranted to address unidentified larval species and seasonal transmission dynamics. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=125 SRC="FIGDIR/small/682237v1_fig2.gif" ALT="Figure 2"> View larger version (12K): org.highwire.dtl.DTLVardef@1f3788forg.highwire.dtl.DTLVardef@1701f58org.highwire.dtl.DTLVardef@19d566org.highwire.dtl.DTLVardef@95716_HPS_FORMAT_FIGEXP M_FIG O_FLOATNOFigure 2.C_FLOATNO Species composition of Anopheles mosquitoes in Kakuma, Kalobeyei, and Dadaab refugee camps, Kenya. (A) Overall relative abundance of Anopheles species identified by PCR and ITS2 sequencing. (B) Spatial distribution and abundance of the predominant species, An. coluzzii and An. arabiensis, across individual sampling sites. C_FIG

ecology↗

bioRxiv2025

The complete mitochondrial genome of Tunga penetrans and insights into flea phylogeny

Tungiasis, one of the oldest and most neglected tropical diseases endemic to sub-Saharan Africa and the Americas, is caused by the female parasitic flea, Tunga penetrans. The flea burrows into the skin, leading to acute and chronic inflammation, often exacerbated by bacterial superinfection. Despite its significant public health impact, genomic studies on T. penetrans are scarce. Here, we present the first complete mitochondrial genome of T. penetrans, comprising 17,279 base pairs and encoding 13 protein-coding genes, 22 transfer RNAs and 2 ribosomal RNAs. Phylogenetic analysis of the cox2 gene revealed a divergent basal lineage from Brazil, supporting a South American origin of T. penetrans and highlights genetic differentiation within the Americas. Clustering of the Ecuadorian and African isolates further suggests historical connections, likely linked to transatlantic maritime trade. The tree highlights a strong South American origin and evidence of migration and diversification, facilitated by human and animal movement. Phylogenetic analysis of the complete genomes relying on the protein-coding genes of other fleas revealed that T. penetrans is closely related to Dorcadia ioffi, a semi-sessile flea of goats and sheep in China. This mitochondrial genome provides a critical resource for future studies on molecular epidemiology, evolutionary history, and control of tungiasis.

genomics↗

bioRxiv2019

Urban ecology of arboviral mosquito vectors along the Kenyan coast

BackgroundThe emergence and re-emergence of arboviral infections particularly Chikungunya, dengue hemorrhagic fever, rift valley fever, and yellow fever in humans around the world threatens global health and security. The purpose of this study was to determine the urban ecology of the common arboviral mosquito vectors in urban Coastal Kenya areas.\n\nMaterials and MethodsThe current study was conducted in urban settings of Kilifi and Mombasa counties in coastal Kenya in 2016 to 2017. Adult mosquitoes were collected both indoors and outdoors by CDC light traps and BG-Sentinel traps respectively. All blood fed mosquitoes were tested for blood meal sources by an Enzyme Linked Immunosorbent Assay (ELISA). Mosquito larvae were collected using standard dippers and pipettes. Egg survivorship in dry soil was evaluated by collecting of soil samples from dry potential breeding habitats, watering them for hatching and rearing of the eventual larvae to adults. Mosquitoes were screened for Flavivirus, Alphavirus, and Phlebovirus arboviruses using Reverse Transcriptase quantitative Polymerase Chain Reaction (RT qPCR).\n\nResultsA total of 3,264 adult mosquitoes belonging to ten species of Culex, Aedes and Anopheles were collected. Overall, the predominant species were Cx. quinquefasciatus 72.4% (n=2,364) and Ae. aegypti, 25.7%, (n=838). A total of 415 breeding habitat types were identified indoors (n=317) and outdoors (n=98). The most productive habitat types in both indoors and outdoors were: assorted small containers, water tanks, drainages, drums and jericans. Overall, 62% (n=18) of the soil samples collected from the two sites (Kilifi and Malindi) were positive for larvae which were used as proxy to measure the presence of eggs. The mosquitoes had high preference for human blood (29.81%) and chicken (3.73%) but none had fed on either goat or bovine. Of 259 mosquitoes tested for viral infection, 11.6% were positive for flavivirus only.\n\nConclusionDomestic and peri-domestic containers were identified to be the key breeding areas of arboviral vectors. Therefore, efforts should be put in place targeting the productive habitat types.

ecology↗