Research Articles (Zoology and Entomology)

Permanent URI for this collection


Recent Submissions

Now showing 1 - 7 of 7
  • ItemOpen Access
    In vivo efficacy of curcumin and curcumin nanoparticle in trypanosoma congolense, broden 1904 (kinetoplastea: trypanosomatidae)-infected mice
    (MDPI, 2023) Molefe-Nyembe, Nthatisi Innocentia; Adeyemi, Oluyomi Stephen; Kondoh, Daisuke; Kato, Kentaro; Inoue, Noboru
    Curcumin (CUR) is known for its wide folkloric effects on various infections; however, its solubility status has remained a hindrance to its bioavailability in the host. This study evaluated the comparative effects of CUR and CUR-nanoparticle in vitro on T. congolense, T. b. brucei, and T. evansi. Additionally, CUR and CUR-nanoparticle anti-Trypanosoma efficacy were assessed in vivo against T. congolense. All the CUR-nanoparticles were two folds more effective on the T. congolense as compared to CUR in vitro, with recorded efficacy of 3.67 ± 0.31; 7.61 ± 1.22; and 6.40 ± 3.07 μM, while the CUR-nanoparticles efficacy was 1.56 ± 0.50; 28.16 ± 9.43 and 13.12 ± 0.13 μM on T. congolense, T. b. brucei, and T. evansi, respectively. Both CUR and CUR-nanoparticles displayed moderate efficacy orally. The efficacy of CUR and CUR-nanoparticles in vivo was influenced by solubility, presence of food, and treatment period. CUR-treated mice were not cured of the infection; however, the survival rate of the orally treated mice was significantly prolonged as compared with intraperitoneal-treated mice. CUR-nanoparticles resulted in significant suppression of parasitemia even though relapsed was observed. In conclusion, CUR and CUR-nanoparticles possess moderate efficacy orally on the trypanosomes as compared to the intraperitoneal treatment.
  • ItemOpen Access
    Counter‑gradient variation and the expensive tissue hypothesis explain parallel brain size reductions at high elevation in cricetid and murid rodents
    (Springer Nature, 2023) Nengovhela, Aluwani; Ivy, Catherine M.; Scott, Graham R.; Denys, Christiane; Taylor, Peter J.
    To better understand functional morphological adaptations to high elevation (> 3000 m above sea level) life in both North American and African mountain-associated rodents, we used microCT scanning to acquire 3D images and a 3D morphometric approach to calculate endocranial volumes and skull lengths. This was done on 113 crania of low-elevation and high-elevation populations in species of North American cricetid mice (two Peromyscus species, n = 53), and African murid rodents of two tribes, Otomyini (five species, n = 49) and Praomyini (four species, n = 11). We tested two distinct hypotheses for how endocranial volume might vary in high-elevation populations: the expensive tissue hypothesis, which predicts that brain and endocranial volumes will be reduced to lessen the costs of growing and maintaining a large brain; and the brain-swelling hypothesis, which predicts that endocranial volumes will be increased either as a direct phenotypic effect or as an adaptation to accommodate brain swelling and thus minimize pathological symptoms of altitude sickness. After correcting for general allometric variation in cranial size, we found that in both North American Peromyscus mice and African laminate-toothed (Otomys) rats, highland rodents had smaller endocranial volumes than lower-elevation rodents, consistent with the expensive tissue hypothesis. In the former group, Peromyscus mice, crania were obtained not just from wild-caught mice from high and low elevations but also from those bred in common-garden laboratory conditions from parents caught from either high or low elevations. Our results in these mice showed that brain size responses to elevation might have a strong genetic basis, which counters an opposite but weaker environmental effect on brain volume. These results potentially suggest that selection may act to reduce brain volume across small mammals at high elevations but further experiments are needed to assess the generality of this conclusion and the nature of underlying mechanisms.
  • ItemOpen Access
    The ground spider genera Leptodrassex Murphy, 2007 and Leptopilos Levy, 2009 (Araneae: Gnaphosidae) in southern Africa, including the description of a new genus and seven new species
    (Magnolia Press, 2022) Haddad, Charles R.; Booysen, Ruan
    The ground spider genera Leptodrassex Murphy, 2007 and Leptopilos Levy, 2009 are recorded from southern Africa for the first time, with the description of five new species: Leptodrassex murphyi sp. nov. (♂ ♀) from Mozambique and South Africa, and L. capensis sp. nov. (♀) from South Africa; Leptopilos butleri sp. nov. (♂ ♀) and L. vasivulva sp. nov. (♂ ♀) from Botswana, South Africa and Zimbabwe, and L. digitus sp. nov. (♂ ♀) from South Africa. Further, the new genus Afrodrassex gen. nov. is described, with the type species A. balrog sp. nov. (♂ ♀) from South Africa and Angola, and A. catharinae sp. nov. (♂ ♀) from South Africa described therein. Details of the somatic and genitalic morphology of all three genera are examined by scanning electron microscopy, and revised descriptions of Leptodrassex and Leptopilos are presented.
  • ItemOpen Access
    High rates of biochar soil amendment cause increased incidences of neurotoxic and oxidative stress in Eisenia fetid (oligochaeta) exposed to glyphosate
    (MDPI, 2022) Dlamini, Nomasonto Portia; Otomo, Patricks Voua
    Despite several known beneficial attributes, biochar is suspected to cause harm to soil organisms when present in relatively high quantities in the soil. To determine the potential detrimental effects of biochar, for 96 h, we exposed the earthworm Eisenia fetida to 0, 2, 4 and 8 mg glyphosate (GLY) per kg in non-amended and biochar-amended soil at rates of 5, 10 and 15%. The results indicated that in non-amended soil, survival was significantly decreased in the highest GLY concentration. Although no median lethal concentration (LC50) could be computed due to the lack of sufficient mortality, in the absence of biochar, a lethal concentration 10% (LC10) of 5.540 mg/kg and a lethal concentration 20% (LC20) of 7.067 mg/kg were calculated. In the biochar-amended soil, no mortality occurred in the control and GLY treatments for all three biochar amendment rates. Biomass results showed significant biomass loss in the highest GLY treatment in the absence of biochar, with an effective concentration of 10% (EC10) of 5.23 mg/kg and an effective concentration of 20% (EC20) of 6.848 mg/kg. In the amended soil, overall, slight non-significant increases in biomass were recorded and no effective concentrations could be calculated due to the lack of significant biomass loss. The assessment of neurotoxicity via the activity of acetylcholine esterase (AChE) showed no change in AchE due to GLY in all the non-amended treatments. However, in the biochar-amended treatments, statistically high levels of AchE occurred (p < 0.05) even in the control (in the absence of GLY). The assessment of oxidative stress through catalase (CAT) activity, showed similar results with no significant effects of GLY alone on CAT activity, but rather dramatic increases in activity in the control and GLY treatments in the biochar-amended soil, with one significant increase in the 10% amended in 8 mg GLY/Kg (p < 0.05). Such significant increases in both AChE and CAT were only observed in soil amended with 10 and 15% biochar. Our findings show that although seemingly beneficial for whole body endpoints, biomarker responses indicate that a biochar amendment higher than 5% adds considerable additional stress to earthworms and should be avoided.
  • ItemOpen Access
    Soil fertilization synergistically enhances the impact of pollination services in increasing seed yield of sunflower under dryland conditions
    (Cambridge University Press, 2021) Adelabu, Dollop Bola; Bredenhand, Emile; Van der Merwe, Sean; Franke, Angelinus Cornelius
    To exploit the potential of ecological intensification during sunflower cropping, it is crucial to understand the potential synergies between crop management and ecosystem services. We therefore examined the effect of pollination intensification on sunflower yield and productivity under various levels of soil fertilization over two seasons in the eastern Free State, South Africa. We manipulated soil fertility with fertilizer applications and pollination with exclusion bags. We found a synergetic effect between pollination and soil fertilization whereby increasing pollination intensity led to a far higher impact on sunflower yield when the soil had been fertilized. Specifically, the intensification of insect pollination increased seed yield by approximately 0.4 ton/ha on nutrient poor soil and by approximately 1.7 ton/ha on moderately fertilized soil. Our findings suggest that sunflower crops on adequate balanced soil fertility will receive abundant insect pollination and may gain more from both synergies than crops grown in areas with degraded soil fertility.
  • ItemOpen Access
    Zulu Poems of (and for) nature: Bhekinkosi Ntuli’s environmental imagination in Imvunge Yemvelo (1972)
    (Cambridge University Press, 2021) Nyambi, Oliver; Otomo, Patricks Voua
    Nature, climate crisis, and the Anthropocene have carved space in recent inter-, cross-, and multi-disciplinary humanities studies. In South Africa, such studies have barely touched literature in African languages. Nyambi and Otomo focus on the tropes of “lady nature,” nostalgia, and dystopia in Zulu writer Bhekinkosi Ntuli’s Imvunge Yemvelo to explore the complex ways in which these tropes test the normative epistemes of ecological crises. Beyond rejecting imperial distortions of indigenous environmentalism, Ntuli’s poems re-center local knowledge of nature in understanding its relationship with humans. That knowledge subverts epistemic structures of colonial conservation, revising and re-visioning racially geo-politicized knowledge hierarchies.
  • ItemOpen Access
    Anthropogenic light, noise, and vegetation cover differentially impact different foraging guilds of bat on an opencast mine in South Africa
    (Frontiers, 2022) Cory-Toussaint, Dawn; Taylor, Peter J.
    Bats are known to be sensitive to changes in their environment. The impact of natural vegetation cover, artificial light intensity and noise (dBA) were investigated on the bat community on the opencast Venetia diamond mine using mixed-effects models. Clutter-feeding bats were virtually absent compared to surrounding natural habitats, suggesting the negative impact of vegetation removal and/or light and/or noise pollution. Mixed-effect models revealed that natural vegetation was the most important factor impacting species richness and overall bat activity. In general, bat activity of both open-air and clutter-edge foragers was negatively impacted over areas close to mining operations that were devoid of vegetation cover. Artificial light only significantly affected feeding activity with less feeding activity in the lit areas. Anthropogenic noise had no significant impact on bat activity and species richness. Our study highlights the importance of vegetation cover and the complexity of the interaction between bats and the environment incorporating anthropogenic factors (artificial lighting, continuous noise, and habitat degradation) and natural factors such as minimum temperature, moon phase, and season that confound trends in bat species richness and responses in relation to opencast mining.