Biology subjects

Getahun, M. N.

Publications and source records attributed to Getahun, M. N..

7 recordsLinked to original sources

bioRxiv2025

Clove-derived eugenol induces strong avoidance behaviour in the invasive fruit fly, Drosophila suzukii

The success of invasive species often relies on sensory adaptations that allow them to exploit new environments. Unlike most of its relatives, the spotted-wing drosophila (Drosophila suzukii) lays eggs in ripening fruit, making it a serious and rapidly spreading agricultural pest worldwide. Spice plants produce volatiles that repel many insects, making them a potential source of D. suzukii behavioural modulators. Here, we examined whether volatiles from clove (Syzygium aromaticum) could alter the behaviour and fitness of D. suzukii. Behavioural assays revealed strong aversion: adults avoided grapes treated with clove extract, while gravid females laid significantly fewer eggs on treated fruit in both no-choice and choice assays. Clove exposure adversely impacted fitness, resulting in slower larval growth, reduced adult weight, decreased emergence rate, and shortened lifespan. Gas Chromatography-mass spectrometry analyses identified eugenol as the predominant volatile. Consistent with this, synthetic eugenol elicited strong avoidance not only in grapes but also across various host fruits, including apple, banana, blueberry, guava, mango, orange, papaya, raspberry, strawberry, and tomato. Furthermore, molecular docking and single-sensillum recordings indicated that eugenol binds most strongly to DsuzOR88a, followed by DsuzOR69a and DsuzOR23a odorant receptors. Subsequently, cheminformatic screening of 1,000 eugenol analogues revealed several structural variants predicted to interact strongly with OR88a, offering additional candidate repellents. By combining behavioural, analytical chemistry, electrophysiological, and cheminformatic approaches, our study demonstrates that clove, through its major volatile eugenol, disrupts host use and reduces fitness in D. suzukii. These results highlight the ecological role of plant-derived repellents in insect-plant interactions and position eugenol as a promising natural compound for sustainable fruit pest management.

ecology↗

bioRxiv2024

Stomoxys flies (Diptera, Muscidae) are competent vectors of multiple livestock hemopathogens

Stomoxys flies are widely distributed and economically significant vectors of various livestock pathogens of veterinary importance. However, the role of Stomoxys spp. in pathogen transmission is poorly understood. Therefore, we studied the feeding patterns of these blood feeders collected from specific locations in Kenya, to identify various vertebrate hosts they fed on, and the livestock hemopathogens they carried, to elucidate their role in pathogens transmission. Our findings show that field-collected Stomoxys flies carried several pathogens including Trypanosoma spp., Anaplasma spp., and Theileria spp. that were also found in the blood of sampled livestock, namely camels and cattle. The findings on blood meal analysis show that Stomoxys flies fed on a variety of domestic and wild vertebrate hosts. We further determined whether Stomoxys spp. are vectors of hemopathogens they harbored by studying the vector competence of S. calcitrans, S. niger niger, and S. boueti species complex, through laboratory and natural experimental in vivo studies. We show that in the process of blood feeding Stomoxys spp. complexes can transmit T. evansi (8.3%) and T. vivax (30%) to Swiss white mice. In addition, field-collected Stomoxy spp. were exposed to healthy mice for blood meal acquisition, and in the process of feeding, they transmitted Theileria mutans and Anaplasma spp. to Swiss white mice (100% infection in the test mice group). All mice infected with both trypanosomes via stomoxys bite died while those infected with Theileria and Anaplasma species did not, demonstrating virulence difference between pathogens. The key finding of this study showing broad feeding host range, cosmopolitan, plethora of pathogens harboured, and efficient vector competence in spreading multiple pathogens suggests profound role of Stomoxys on pathogen transmission and infection prevalence in livestock. Author summaryStomoxys flies are highly adaptable to several ecological settings, including metropolitan areas. In contrast, tsetse flies (genus Glossina), the main biological vectors of African trypanosomes, have a limited distribution to parks and other conservation areas. Stomoxys flies could play a significant role in the spread of animal African trypanosomes, among other hemopathogens, particularly in areas with or without tsetse infestation. Although there have been speculations about the potential role of Stomoxys flies in the transmission of various pathogens, there is lack of data to link hemopathogens occurring in both bloodmeal hosts of Stomoxys and in the flies, and further in vivo experimental studies to confirm the vector competence of Stomoxyine flies. Here, we explored a host and pathogens network, and investigated species diversity at various ecologies, and demonstrated that Stomoxys flies feed on diverse vertebrate hosts and are infected with a plethora of pathogens. We also showed experimentally that they could transmit some of these hemopathogens to mice, for instance, T. vivax, T. evansi, Theileria mutans, and Anaplasma spp. with varying infection success rates. Stomoxys flies could play a significant role in transmitting and spreading various hemopathogens of veterinary importance and possibly maintaining their circulation in livestock, which could explain the occurrence of animal African trypanosomes in the regions outside the tsetse belts.

pathology↗

bioRxiv2024

Exploring the dynamic ticks-camel-pathogens interaction

The ability of ticks to interact and adapt to different ecologies and hosts determines their vectorial competence for various pathogens, however ticks-livestock-pathogens interaction studies are limited. With our ticks-hosts-pathogens interface studies, we found 14 species of ticks feeding on various livestock. Ticks showed a strong preference for one-humped camels (Camelus dromedarius). The camel nostril was the most preferred predilection site. The most prevalent tick species on camels was Hyalomma rufipes. We found two novel Amblyomma gemma variants which are distinct both morphologically and genetically from previously described Amblyomma gemma. The signature odors from camel breath and body were attractive to H. rufipes; demonstrating ticks utilize camel-derived metabolites to find their host. Our research shows that H. rufipes and camel hosts have unique and shared pathogens showing H. rufipes vector and camels reservoir host qualities. Our study unravels the dynamic interactions between ticks, pathogens, and camels that all influence the likelihood of pathogen adaptation and transmission dynamics. IMPORTANCETicks are obligatory hematophagous arachnids, serving as vectors for a wide array of pathogens that can be transmitted to animals and humans. The ability of ticks to acquire and transmit various pathogens depends on its attraction to quality reservoir host and the survival of the pathogens in ticks gut and other tissues. However, the complex dynamics of tick-pathogens interaction and host-seeking behavior remains understudied. This investigation revealed notable variation in tick preference for domestic animals, camel being the most preferred host. Moreover, our spatial analysis about tick attachment sites showed nostril is the most preferred sites by various tick species. Our epidemiology data showed variation in the pathogens harbored by camel (host) and vector (H. rufipes), demonstrating the camels efficiency as reservoir host and ticks vector competence for various pathogens. With our behavioral experiment using H. rufipes and its preferred hosts (camel) breath and body signature odors, we identified novel attractants for H. rufipes, thus offering new avenues for combating TBDs. Overall, our study presents novel insights into how multiple factors shape tick-host-pathogens interaction.

ecology↗

bioRxiv2024

Multimodal interactions in Stomoxys navigation reveals synergy between olfaction and vision.

Stomoxys flies exhibit an attraction towards objects that offer no rewards, such as traps and targets devoid of blood or nectar incentives. This behavior provides an opportunity to develop effective tools for vector control and monitoring. However, for these systems to be sustainable and eco-friendly, the visual cues used must be selective in attracting the target vector(s). In this study, we modified the existing blue Vavoua trap, originally designed to attract biting flies, to create a deceptive host attraction system specifically biased towards attracting Stomoxys. Our research reveals that Stomoxys flies are attracted to various colors, with red proving to be the most attractive and selective color for Stomoxys compared to other colors tested. Interestingly, our investigation on cattle-Stomoxys interaction demonstrates that Stomoxys flies do not have preference for a specific livestock fur color phenotype, despite variation in spectrum. To create a realistic sensory impression of the trap in the Stomoxys nervous system, we incorporated olfactory cues from livestock host odors that significantly increased trap catches. The optimized novel nanopolymer bead dispenser capable of effectively releasing the attractive odor, carvone + p-cresol, with strong plume strands, longevity. Overall, red trap baited with nano polymer beads dispenser is environmentally preferred.

ecology↗

bioRxiv2023

Multi-omics analyses reveal rumen microbes and secondary metabolites that are unique to livestock species

Ruminant livestock like cattle, sheep, goat, and camel, have a unique digestive system with complex microbiota communities that facilitate feed conversion and production of various secondary metabolites including greenhouse gases, which are significant in livestock-vector and livestock environment interactions. However, there is limited understanding of the diversity of rumen microbes and secondary metabolites that have advantageous traits to livestock physiology, productivity, climate, and defense across different ruminant species. In this study using metagenomics and metabolomics data from four evolutionary distinct livestock species, we show that there are signature microbes and secondary metabolites for each species. For instance, camels host a unique anaerobic fungus(F) called Oontomyces, cattle harbor more unique microbes like Psychrobacter (F) and three unique bacteria genera Anaeromyces, Cyllamyces, and Orpinomyces. Goats have Cleistothelebolus (F), while sheep host Liebetanzomyces (F). This phenomenon may indicate that there are species-specific microbes that requires host rumen-microbes environment balance. Additionally, there are conserved core bacterial microbes present and in equal abundance regardless of the host genetics, indicating their essential role in maintaining crucial functions. The studied livestock fed on diverse plant materials, including grass, shrubs to acacia trees. Regarding secondary metabolites camel rumen is rich in organic acids, goat with alcohols, and hydrocarbons, sheep with indoles and cattle with sesquiterpenes. These results have implications for manipulating the rumen environment to target specific microbes and secondary metabolite networks, thereby enhancing livestock productivity, resilience, reducing susceptibility to vectors, and environmentally preferred livestock husbandry. IMPORTANCERumen fermentation that depends on feed component and rumen microbes plays a crucial role in feed conversion and production of various metabolites, important for physiological functions, health and environmental smartness of ruminant livestock, in addition to providing food for humans. However, given the complexity and variation of the rumen ecosystem and feed of these various livestock species combined with inter-individual differences between gut microbial communities, how they influence the rumen secondary metabolites remains elusive. Using metagenomics and metabolomics approaches, we show that each livestock species has signature microbe(s) and secondary metabolites. These findings may contribute towards understanding rumen ecosystem, microbiome and metabolite networks, that mayprovide a gateway to manipulate rumen ecosystem pathways towards making livestock production, efficient, sustainable and environmentally friendly.

microbiology↗

bioRxiv2021

Transmission of Candidatus Anaplasma camelii to laboratory animals by camel-specific keds, Hippobosca camelina

Anaplasmosis, caused by infection with bacteria of the genus Anaplasma is an important veterinary and zoonotic disease. The characterization of transmission has concentrated on ticks and little is known about non-tick vectors of livestock anaplasmosis. This study investigated the presence of Anaplasma spp. in camels in northern Kenya and whether the hematophagous camel ked, Hippobosca camelina, acts as a vector. Camels (n = 976) and > 10,000 keds were sampled over a three-year study period and the presence of Anaplasma species was determined by PCR-based assays targeting the Anaplasmataceae 16S rRNA gene. Camels were infected by Candidatus Anaplasma camelii occurring from 63 - 78% during the dry (September 2017), wet (June-July 2018), and late wet seasons (July-August 2019). 10 - 29% of camel keds harbored Ca. Anaplasma camelii acquired from infected camels during blood feeding. We determined whether Anaplasma positive camel keds could transmit Ca. Anaplasma camelii to small laboratory animals via blood-feeding. We show competence in pathogen transmission and subsequent infection in mice and rabbits by both direct detection in blood smears and subsequent molecular identification by PCR. Transmission of Ca. Anaplasma camelii to mice (8 - 47%) and rabbits (25%) occurred readily after ked bites. Hence, we demonstrate, for the first time, the potential of H. camelina as a vector of anaplasmosis. This key finding provides the basis for establishing ked control programmes for improvement of livestock and human health. Author summaryHematophagous flies such as Tabanids and Stomoxys, among other biting flies, are mechanical transmitters of various pathogens such as African trypanosomes and Anaplasma species. However, little is known about the role of common camel-specific biting keds (also known as camel flies or louse flies, genus Hippobosca) in pathogen transmission. Keds inflict painful bites to access host blood, and in the process may transmit bacterial hemopathogens frequently detected in both camels and their keds. We confirmed by experimental blood-feeding, gene amplification, and amplicon sequencing that camel keds can transmit "Candidatus Anaplasma camelii" from naturally-infected camels to healthy mice and rabbits. The high prevalence of camel anaplasmosis throughout the year in northern Kenya could be explained by the infestation camel-specific H. camelina, whose capacity as efficient fliers, unlike ticks, promotes disease transmission and maintenance within and among camel herds. Although this study focused on the transmission of Anaplasma sp. by camel keds, it is possible that other hemopathogens could also be transmitted by these flies through a similar mechanism. Notably, in the absence of their preferred hosts, keds occasionally bite humans and other vertebrates they come across in order to acquire bloodmeals, and in the process could transmit zoonotic pathogens.

microbiology↗

bioRxiv2020

Molecular characterization of pathogenic African trypanosomes in biting flies and camels in surra-endemic areas outside the tsetse fly belt in Kenya

BackgroundAfrican animal trypanosomosis is becoming prevalent beyond its traditionally defined geographical boundaries and is a threat to animals beyond the tsetse belts in and outside Africa. However, knowledge of infections with clinically important trypanosome species and their diversity among field-collected hematophagous biting flies and domestic animals is limited mainly to tsetse and their mammalian hosts in tsetse-infested areas. This study aimed to examine the presence of trypanosomes in both biting flies and domestic animals outside the tsetse belt in northern Kenya, potential mechanical vector species, and their host-feeding profiles. MethodsWe screened for pathogenic African trypanosomes in blood samples from domestic animals and field-trapped flies by microscopy and sequencing of internal transcribed spacer (ITS1) gene PCR products. We sequenced kinetoplast maxicircle genes to confirm Trypanosoma brucei detection and the RoTat 1.2 and kinetoplast minicircle genes to differentiate type-A and type-B Trypanosoma evansi, respectively. Further, we identified the hosts that field-trapped flies fed on by PCR-HRM and sequencing of 16S rRNA genes. ResultsHippobosca camelina, Stomoxys calcitrans, Tabanus spp., and Pangonia rueppellii are potential vectors of trypanosomes outside the tsetse belt in Marsabit County, northern Kenya. We identified Trypanosoma spp., including Trypanosoma vivax, T. evansi, T. brucei, and T. congolense in these biting flies as well as in camels (Camelus dromedarius). Trypanosomes detected varied from single up to three trypanosome species in H. camelina and camels in areas where no tsetse flies were trapped. Similar trypanosomes were detected in Glossina pallidipes collected from a tsetse-infested area in Shimba Hills, coastal Kenya, showing the wide geographic distribution of trypanosomes. Furthermore, we show that these biting flies acquired blood meals from camels, cattle, goats, and sheep. Phylogenetic analysis revealed diverse Trypanosoma spp. associated with variations in virulence and epidemiology in camels, which suggests that camel trypanosomosis may be due to mixed trypanosome infections rather than only surra (T. evansi), as previously thought.

pathology↗