Research Articles (Zoology and Entomology)

Permanent URI for this collectionhttp://hdl.handle.net/2263/1740

A collection containing some of the full text peer-reviewed/ refereed articles published by researchers from
the Department of Zoology and Entomology

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Megagrazer loss drives complex landscape-scale biophysical cascades
(IOP Publishing, 2025-01) Hyvarinen, Olli; Te Beest, Mariska; Le Roux, Elizabeth; Kerley, Graham I.H.; Buitenwerf, Robert; Druce, Dave J.; Chen, Jiquan; Rapp, Linda; Fernandes, Joana; Cromsigt, Joris P.G.M.
Wild animals can modulate ecosystem-climate feedbacks, e.g. through impacts on vegetation and associated carbon dynamics. However, vegetation cover and composition also affect land surface albedo, which is an important component of the global energy budget. We currently know very little about the influence of wild animals on land surface albedo and the resulting climate forcing of these albedo changes. Leveraging a unique, ecosystem-scale, semi-experimental approach, we study how the local removals of the world's largest, terrestrial grazer, white rhinoceros (Ceratotherium simum), affected the coupling between fire dynamics, woody encroachment and surface albedo in Hluhluwe–iMfolozi Park (HiP), South Africa. Our path analysis revealed that areas in the park where more rhinos had been removed showed a stronger increase in burnt area and woody encroachment compared to areas with fewer rhinos removed, which were both related to a decrease in surface albedo. Increasing burnt area was further associated with higher rates of woody encroachment, indirectly reinforcing the negative effect of rhino loss on albedo. Our study demonstrates that removals of megagrazers in HiP were related to complex ecosystem-wide cascades with measurable impacts on land cover and surface albedo and consequences on climate forcing. This highlights the importance of restoring functional ecosystems by reinstating trophic processes.
Crop mixtures influence fall armyworm infestation and natural enemy abundance in maize-based intercropping systems
(Springer, 2024-12) Peter, Emmanuel; Yusuf, Abdullahi Ahmed; Subramanian, Sevgan; Kruger, Kerstin; Karlsson Green, Kristina; Anderson, Peter; Torto, Baldwyn; Tamiru, Amanuel
The fall armyworm (FAW), Spodoptera frugiperda (J. E. Smith), causes significant damage to maize, threatening the food security and livelihood of millions of smallholder farmers in sub-Saharan Africa (SSA). Crop diversification has been recommended as an ecologically sustainable FAW control option. However, limited information is available on the impacts of companion plants and their control mechanisms against FAW in SSA, being a relatively new pest to the region. Building upon our earlier laboratory study, which elucidated how edible companion intercrops effectively reduce FAW infestation, we conducted field experiments in Kenya to assess the effectiveness of intercropping maize with beans, groundnut, cassava and sweet potato under realistic field conditions. Growing maize with these intercrops consistently resulted in fewer FAW eggs, larvae and lower plant infestation compared to maize monoculture except with cassava. Additionally, maize under these intercrops experienced low FAW damage and higher crop yield compared to maize monoculture. Maize growth stages significantly influenced the population of FAW eggs and larvae, with a peak observed between vegetative stages V4 and V10. Furthermore, intercropped maize plots exhibited a higher presence of FAW predators, such as lady beetles and earwigs. Correlation analysis revealed a significant correlation between temperature, relative humidity, and the population of FAW life stages and natural enemies at the experimental sites. Therefore, intercropping maize with beans, sweet potato, and groundnuts can be incorporated into an integrated FAW management strategy to sustainably control the pest in real farming conditions. These findings are particularly relevant for small-scale farmers in Africa and beyond, who cannot afford expensive FAW control using insecticides.
Small-scale fires interact with herbivore feedbacks to create persistent grazing lawn environments
(Wiley, 2024-07) Singh, Jenia; Donaldson, Jason E.; Archibald, Sally; Parr, Catherine Lucy; Voysey, Michael D.; Davies, Andrew B.
Fire-herbivory feedbacks strongly influence the formation of grazing lawns in savanna ecosystems. Preliminary findings suggest that small-scale (<25 ha) fires can engineer grazing lawns by concentrating herbivores on the post-burn green flush; however, the persistence of such grazing lawns over the longer term and without repeated fire is unknown. We used high-resolution Light Detection and Ranging (LiDAR) to investigate the long-term effects of fire manipulation on short grass structure (height, cover, volume and spatial continuity) and grazing lawn establishment in Kruger National Park, South Africa. We analysed the effects of fire exclusion and experimental burns applied over a 7-year period (2013–2019) followed by a 1-year cessation of burning at varying spatial scales during the early and late dry seasons. Fires contributed a fourfold increase in short grass cover, regardless of fire season or size. The distribution of grass height differed significantly between fire-induced grazing lawns and recently unburnt parts of the landscape where controlled fires were excluded over the experimental period. The volume (corresponding to bulk density) of short grass on the landscape responded strongly to fires, with grass volume <20 cm in height increasing with both early and late dry season fires. Early dry season fires caused larger and more homogeneous short grass patches. Furthermore, early dry season fires were more influential in increasing the cover of the shortest grass height class (1–5 cm). Synthesis and applications. Our results demonstrate that fire-induced grazing lawns can persist over the longer term, even when fires are no longer applied, leading to the creation of vertical and horizontal heterogeneity in the grass layer. Small-scale fires, therefore, represent a feasible management approach to expanding grazing lawn extent, potentially benefiting grazer coexistence and diversity.
High human presence is correlated with lower faecal glucocorticoid metabolite levels in an urban bird population
(Elsevier, 2025-04) Nhlapo, Kagiso B.; Cunningham, Susan J.; Sumasgutner, Petra; Ganswindt, Andre; McKechnie, Andrew E.; Ngcamphalala, Celiwe A.
Urban wildlife must cope with diverse challenges and stressors, including human presence. However, in addition to being a disturbance, humans can provide energy-rich food and protection from predators. We evaluated the impact of human presence on red-winged starlings (Onychognathus morio) in a highly urbanised environment using faecal glucocorticoid metabolite (fGCM) concentrations as a stress-related biomarker. We performed an adrenocorticotropic hormone (ACTH) challenge to validate a non-invasive method for quantifying glucocorticoids in red-winged starlings. Using this method, we quantified fGCMs in excreta collected from free-living starlings during weekdays (high human presence) and weekends (low human presence) to determine the birds' responses to fluctuating human numbers. Following the ACTH challenge, starlings' circulating glucocorticoid (GC) concentrations increased by 127 % within 30 min and the corresponding fGCM concentrations increased within 1 h of injection. Of the four enzyme immunoassays (EIA) tested, an 11-oxoaetiocholanolone EIA, performed best, detecting a 310 % increase in fGCM concentrations post-ACTH challenge and suggested a 1-h lag between injection and peak fGCM excretion in this species. Human foot-traffic was significantly higher on weekdays compared to weekends, yet free-living red-winged starlings showed overall 30.4 % lower fGCM concentrations on weekdays compared to weekends. Red-winged starlings consume a higher proportion of anthropogenic food on weekdays than weekends and we cannot rule out the possibility that diet-related alteration in gut passage time affect fGCM concentrations. However, the correlation between fGCMs and human foot traffic may also suggest urban red-winged starlings benefit from human presence. Our results raise the possibility that, under certain conditions, the benefits associated with human presence outweigh potential negative effects associated with human activity, at least during the non-breeding season.
Steering conservation biocontrol at the frontlines : a fuzzy logic approach unleashing potentials of climate-smart intercropping as a component within the integrated management of fall armyworm in Africa
(Elsevier, 2025-02) Agboka, Komi Mensah; Tonnang, Henri E.Z.; Kimathi, Emily; Abdel-Rahman, Elfatih M.; Odindi, John; Mutanga, Onisimo; Niassy, Saliou
This study introduces a computational index that employs fuzzy sets theory to identify potential deployment sites for push-pull as a component in the integrated management of Fall Armyworm (FAW) in Africa. The index, validated through known push-pull testing sites and informed by insights from field data and practical observations, is primarily based on companion plants (Desmodium intortum and Brachiaria brizantha), livestock, and maize as covariates. The study developed a set of rules linking each selected covariate to the output as membership functions, which are later combined using an algebraic operator. It identifies extensive maize farms across Africa potentially suitable for push-pull technology, although the suitability varies by region. Farms in the eastern and southern regions are predicted to be highly suitable, while the suitability of farms in West Africa is expected to improve over time due to the perennial nature and agronomic benefits of companion plants. The index is proposed as a metric for deploying push-pull technology, providing a roadmap for effective agronomic practices in Africa, and assisting farmers and decision-makers in the integrated management of FAW. Overall, our results indicate that the fuzzy-based computational index is an effective tool for identifying potential areas to maximise the benefits of push-pull technology as a key component of integrated FAW management. Our study identifies appropriate areas for application, allowing for the careful use of resources and increasing the likelihood of effective pest management. This approach will ultimately safeguard cereal crops, boost agricultural productivity, and aid in ensuring food security in Africa.
Integrating habitat suitability modeling with gene flow improves delineation of landscape connections among African savanna elephants
(Springer, 2024-09) De Flamingh, Alida; Alexander, Nathan; Perrin-Stowe, Tolulope I.N.; Donnelly, Cassidy; Guldemond, Robert Abraham Rene; Schooley, Robert L.; Van Aarde, Rudi J.
Across Africa, space for conservation is sometimes limited to formally protected areas that have become progressively more isolated. There is a need for targeted conservation initiatives such as the demarcation of landscape connections, defined as areas that encompass environmental variables that promote the natural movement of individuals between populations, which can facilitate gene flow. Landscape connections can mitigate genetic isolation, genetic drift, and inbreeding, which can occur in isolated populations in protected areas. Promoting gene flow can reduce the risk of extirpation often associated with isolated populations. Here we develop and test models for identifying landscape connections among African savannah elephant (Loxodonta africana) populations by combining habitat suitability modeling with gene flow estimates across a large region including seven countries. We find a pronounced non-linear response to unsuitable habitat, consistent with previous studies showing that non-transformed habitat models are poor predictors of gene flow. We generated a landscape connections map that considers both suitable habitats based on telemetry occurrence data and gene flow estimated as the inverse of individual genetic distance, delineating areas that are important for maintaining elephant population connectivity. Our approach represents a novel framework for developing spatially and genetically informed conservation strategies for elephants and many other taxa distributed across heterogeneous and fragmented landscapes.
A novel integrated computational approach for agroecological similarity
(Elsevier, 2025-06) Tonle, Franck B.N.; Tonnang, Henri E.Z.; Ndadji, Milliam M.Z.; Tchendji, Maurice T.; Nzeukou, Armand; Niassy, Saliou
Assessing agroecological similarity is crucial for shaping sustainable agricultural practices and resource allocation, especially in regions undergoing rapid environmental changes. Current evaluation methods face challenges such as managing large datasets, adjusting for temporal variations across locations, and the need for accessible, comprehensive analytical tools. Addressing these challenges, this paper presents the Agroecology Fourier-based Similarity Assessment (AFSA), an innovative computational approach that applies principles of the Fourier transform to systematically evaluate similarities among agroecological sites. To enhance usability, AFSA is complemented by webafsa, a user-friendly web application designed for researchers and policymakers, emphasizing ease of use and broad applicability. The implementation of AFSA and webafsa aims to improve land suitability assessments, enhance decision-making for resource allocation, and support better adaptation strategies for sustainable agriculture. By offering both a sophisticated computational methodology and an accessible decision-support tool, this study paves the way for more informed and environmentally considerate agricultural practices.
The impact of the lunar cycle and season on small mammal communities near a large metropolitan area
(Wiley, 2025-05) Oosthuizen, Tasha; Oosthuizen, Maria Kathleen; Pillay, Neville
Small mammals are prey to a range of predators and consequently use environmental cues, such as light, to assess the level of predation risk in their environment. The lunar cycle significantly influences the fear landscape for prey species because their risk level varies with visibility. We conducted small mammal surveys in two communities in close proximity to each other on a peri-urban site in South Africa. We investigated the abundance, composition and diversity of these communities across the lunar cycle and seasons. As predicted, we trapped the highest number of individuals and species on new moon nights, which have low light levels and thus indicate a reduced perceived predation risk. Winter showed a higher abundance compared to the other seasons, which could be explained by a decline in naturally available resources in winter. We captured more individuals and species on one site compared to the other site, largely because of the different microhabitats in the two sites; one site had a lower density of trees and more bare soil areas. Our study provides the first evidence of the impact the lunar cycle has on small mammal communities in southern Africa. Based on our findings of decreased activity of small mammals under increased lunar visibility, we hypothesise that small mammal communities in southern Africa will be negatively affected by the increased occurrence of artificial light at night, which could have wider ecosystem impacts.
Birds with distinct ecological traits show varied haemoglobin adaptations along elevation gradients
(Wiley, 2025-04) Bhembe, Zamekile D.; Padidar, Sara; Bebbington, Kat; Kingma, Sjouke A.; Monadjem, Ara
Ecological systems are highly dynamic, with organisms continually adapting to various environmental stressors along natural gradients. Birds along elevation gradients serve as excellent models for examining physiological adaptations, such as elevated haemoglobin concentrations at high altitudes due to lower oxygen availability. This study aimed to examine how various ecological traits influence the haemoglobin concentration responses of multiple bird taxa to an elevation gradient. We measured haemoglobin concentration in 920 birds of 133 species at six sites representing an elevation gradient spanning from 60 to 1,600 m above sea level. Using MCMC Bayesian mixed models, we identified important ecological determinants of haemoglobin concentration and further ran separate models to test whether haemoglobin concentration responses to elevation differ between various functional groups of birds. Our results showed that haemoglobin concentration increased significantly with elevation and was strongly influenced by wing morphology, body mass, season, and primary lifestyle. The rate of increase with elevation varied by lifestyle: terrestrial and perching birds exhibited a steeper increase in haemoglobin concentration with elevation, while aerial birds also increased haemoglobin but at a more gradual rate. However, the remaining traits did not alter how species respond to hypoxia; for example, birds increased haemoglobin at the same rate in both the dry and wet seasons, meaning seasonal changes did not strongly impact elevation-driven haemoglobin adjustments. Elevation is the primary driver of variation, while lifestyle influences baseline levels rather than the rate of change. Despite differences in lifestyle-driven oxygen demands, birds exhibit a similar haemoglobin response to hypoxia at moderate elevations, where adjustments remain within physiological limits, indicating that hypoxia-driven haemoglobin adjustments occur independently of baseline oxygen demands. These findings demonstrate how birds regulate oxygen transport relative to ecological constraints, providing insights into their physiological flexibility across environmental gradients.
Thermal performance drifts between the egg parasitoid Telenomus remus and the fall armyworm may threaten the efficacy of biological control under climate change
(Wiley, 2025-05) Mubayiwa, Macdonald; Machekano, Honest; Mvumi, Brighton M.; Opio, Winnifred A.; Segaiso, Bame; Chidawanyika, Frank; Nyamukondiwa, Casper
The fall armyworm, Spodoptera frugiperda J.E. Smith, is a significant global agricultural pest known for its rapid invasion and devastating impact on crops. While pesticides may be effective for controlling the pest in the short-term, they cause several socioeconomic and ecological costs that highlight the need for more sustainable management strategies. Telenomus remus (Nixon) is a promising egg parasitoid for its biological control. For the parasitoid to provide effective ecosystem services, it should be able to survive and coexist within the same ecological niches as its host. However, there is limited information regarding the potential responses of T. remus to thermal changes. In the context of the changing climate environments, it is key to understand the parasitoid's overall environmental fitness in relation to its host. We investigated the effects of short-term (2 h) and long-term (6 h) acclimation pretreatment of T. remus adults and S. frugiperda eggs to high and low temperatures (18°C and 32°C, respectively) in comparison with the control (28°C). Telenomus remus thermal fitness (critical thermal maxima [CTmax], heat knockdown time and critical thermal minima [CTmin]), parasitism rates, and adult emergence were determined. Pretreated S. frugiperda eggs were assessed for hatchability under the control conditions. Acclimation at low (18°C) and high (32°C) temperatures significantly reduced and increased heat tolerance, respectively. Both temperatures, however, reduced cold tolerance. The parasitoid thermal tolerance polygons following acclimation pretreatment, showed significant heat- but not cold-tolerance gains. Fall armyworm eggs short-term acclimated to 32°C had significantly higher (p < 0.05) but comparable hatchability to the control treatment. Similarly, parasitism and adult emergence rates were significantly lower (p < 0.001) following long-term acclimation of host eggs and the parasitoid to 32°C. These findings suggest that high temperatures may decouple the T. remus-fall armyworm ecological relationship, threatening its success in warming regions. The findings provide valuable insights into the potential environmental resilience and suitability of T. remus as a biological control agent across different climates or geographies.
Evolution of sex differences in cooperation can be explained by trade-offs with dispersal
(Public Library of Science, 2024-10-24) York, Jennifer E.
Explaining the evolution of sex differences in cooperation remains a major challenge. Comparative studies highlight that offspring of the more philopatric sex tend to be more cooperative within their family groups than those of the more dispersive sex but we do not understand why. The leading “Philopatry hypothesis” proposes that the more philopatric sex cooperates more because their higher likelihood of natal breeding increases the direct fitness benefits of natal cooperation. However, the “Dispersal trade-off hypothesis” proposes that the more dispersive sex cooperates less because preparations for dispersal, such as extra-territorial prospecting, trade-off against natal cooperation. Here, we test both hypotheses in cooperatively breeding white-browed sparrow weavers (Plocepasser mahali), using a novel high-resolution automated radio-tracking method. First, we show that males are the more dispersive sex (a rare reversal of the typical avian sex difference in dispersal) and that, consistent with the predictions of both hypotheses, females contribute substantially more than males to cooperative care while within the natal group. However, the Philopatry hypothesis cannot readily explain this female-biased cooperation, as females are not more likely than males to breed within their natal group. Instead, our radio-tracking findings support the Dispersal trade-off hypothesis: males conduct pre-dispersal extra-territorial prospecting forays at higher rates than females and prospecting appears to trade-off against natal cooperation. Our findings thus highlight that the evolution of sex differences in cooperation could be widely attributable to trade-offs between cooperation and dispersal; a potentially general explanation that does not demand that cooperation yields direct fitness benefits.
Mulching of post-harvest residues and delayed planting improves fungal biodiversity in South African Eucalyptus plantations and enhances plantation productivity
(Elsevier, 2025-06) Bose, Tanay; Roux, Jolanda; Titshall, Louis; Dovey, Steven B.; Hammerbacher, Almuth; tanay.bose@fabi.up.ac.za
Short-rotation Eucalyptus plantations provide essential forest products, with productivity and soil health influenced by residue management and planting strategies. This study examined the effects of burning or mulching post-harvest residue followed by immediate versus delayed planting on soil fungal biodiversity, soil properties, and tree growth across four sites in KwaZulu-Natal, South Africa. Plots were planted either three months ('immediate') or six months ('delayed') after treatment implementation. Volume measurements assessed tree growth, and soil attributes, including moisture, temperature, and nutrient levels, were analyzed. Soil samples were collected in November 2019 and March 2022, and fungal communities were analyzed through high-throughput sequencing targeting the internal transcribed spacer 1 (ITS1) region. Data emerging from this study showed mulched plots had significantly higher tree volume, with delayed planting increasing productivity by 13.6 % at 24–36 months and 25 % at 36–48 months post-planting. Soil moisture was 1.3–2 times higher in mulched plots than in burnt plots. Mulching significantly reduced the maximum soil temperatures by 4.5–6.8 °C. Four months after treatment, burnt plots had higher pH (1.1-fold), carbon (2.2-fold), phosphate (1.6-fold) and manganese (2.5-fold). Initially, mulched plots had lower fungal biodiversity (0.81-fold) than burnt plots but surpassed them after 28 months (1.28-fold increase). Fungal community overlap declined from 83.28 % to 40.64 %, with mulching supporting higher saprotroph (1.3-fold) and symbiotroph (1.25-fold) abundances, while delayed planting increased pathotroph presence by 1.5-fold in burnt plots. These findings highlight the long-term benefits of mulching and delayed planting in enhancing fungal biodiversity, promoting beneficial microbial communities, and improving tree growth, contributing to more sustainable Eucalyptus plantation management.
Oxidative stress in the reproduction of mammals
(MDPI, 2025-03) Jacobs, Paul Juan; Bennett, Nigel Charles; pj.jacobs@up.ac.za
No abstract available.
An assessment of vegetable production constraints, trait preferences and willingness to adopt sustainable intensification options in Kenya and Uganda
(Frontiers Media, 2025-04) Okoma, Rose N.; Omuse, Evanson R.; Mutyambai, Daniel M.; Beesigamukama, Dennis; Murongo, Marius F.; Subramanian, Sevgan; Chidawanyika, Frank
Global food production systems are under pressure due to population increase, limited farmland, biotic and abiotic constrains, and ongoing climate change. Sustainable intensification is needed to increase agricultural productivity with minimal adverse environmental and social impacts. Vegetable-integrated push pull (VIPP) technology coupled with black soldier fly (BSF) frass offer such opportunities to smallholder farmers. However, farmers’ vegetable preferences and willingness to adopt these innovations remain unknown and are variable across various geographic scales. Focus group discussions (FGDs) and in-person interviews with smallholder farmers were conducted to assess vegetable production constraints and select vegetables to be integrated into VIPP coupled with BSF frass biofertilizer in Kenya and Uganda. Twenty-six FGDs followed by in-person interviews were conducted from July to November 2023 with 227 and 106 farmers from Kenya and Uganda, respectively. A total of 23 vegetable types were identified. The most considered discerning parameters and traits included household consumption, income generation, nutritional value, extended harvesting, drought tolerance and resistance to diseases and insect pests. The major constraints were the high cost of agrochemicals and fertilizers and poor seed quality in Kenya while diseases, pests, drought and poor rainfall, low soil fertility, too much rainfall and floods, high cost of agrochemicals and fertilizers, lack of seeds and poor seed quality were pressing constraints among farmers in Uganda. More than 83% of farmers showed readiness to adopt a combination of VIPP+BSF. Kales, spinach, cabbage, Amaranthus, African nightshade and tomatoes were preferred in central Kenya whereas cowpeas, kales, African nightshade, Amaranthus, pumpkin leaves and spider plants in western Kenya were preferred as vegetables to be included in VIPP and BSF frass innovations. Ugandan farmers considered eggplants, Amaranthus, garden eggs, cabbage, kales and tomatoes the most popular vegetables to be incorporated in VIPP and BSF frass innovations. Our results provide a baseline for vegetables to be integrated into VIPP with BSF frass biofertilizer for validation with farmers. The study also underlies how farmer crop preferences vary according to site and the need for participatory selection to increase the chances of adoption of agricultural interventions.
Production of fusel alcohols and fusel acetates by pathogenic fungi in the Ceratocystidaceae
(Elsevier, 2025-08) Mailula, Dineo M.; Wingfield, Brenda D.; Van der Nest, Magrieta Aletta; Hammerbacher, Almuth; almuth.hammerbacher@fabi.up.ac.za
The family Ceratocystidaceae includes economically important plant pathogens that vary in host preference and lifestyle. These fungi are believed to attract insect vectors, for their dispersal through their floral and fruity scents. This study aimed to identify the volatiles produced by a subset of fungi within the Ceratocystidaceae using gas chromatography coupled with mass spectrometry. The primary volatiles produced by most genera in the family were fusel alcohols and fusel acetates, but their emission rates differed significantly between genera and isolates from a single species. Ceratocystis albifundus collected from Protea cynaroides produced higher levels of fusel acetates compared to isolates from Terminalia sericea. In addition, significant differences in volatile biosynthesis were observed between isolates grown under different temperatures. Results of this study demonstrate that Ceratocystidaceae exhibit varied volatile profiles, but further research is needed to understand the ecological and physiological mechanisms underlying this plasticity.
The latitudinal biotic interaction hypothesis revisited : contrasting latitudinal richness gradients in actively vs. passively accumulated interaction partners of honey bees
(BioMed Central, 2025-03) Cirtwill, Alyssa R.; Roslin, Tomas; Pena-Aguilera, Pablo; Agboto, Agathe; Berce, William; Bondarchuk, Svetlana N.; Brodschneider, Robert; Heidari, Behzad; Kaizirege, Camara; Nyaga, Justine Muhoro; Ekpah, Ojonugwa; Gomez, Gonzalo Ossa; Paz, Claudia; Pirk, Christian Walter Werner; Salehi-Najafabadi, Amir; Salonen, Anneli; Soloniaina, Chantal; Wirta, Helena
BACKGROUND : Contrasting hypotheses suggest that the number of biotic interactions per species could either increase towards the equator due to the increasing richness of potential interaction partners (Neutral theory), or decrease in the tropics due to increased biotic competition (Latitudinal Biotic Interaction Hypothesis). Empirical testing of these hypotheses remains limited due to practical limitations, differences in methodology, and species turnover across latitudes. Here, we focus on a single species with a worldwide distribution, the honey bee (Apis mellifera L.), to assess how the number of different types of interactions vary across latitudes. Foraging honey bees interact with many organisms in their local environment, including plants they actively select to visit and microbes that they largely encounter passively (i.e., unintentionally and more or less randomly). Tissue pieces and spores of these organisms are carried to the hive by foraging honey bees and end up preserved within honey, providing a rich record of the species honey bees encounter in nature. RESULTS : Using honey samples from around the globe, we show that while honey bees visit more plant taxa at higher latitudes, they encounter more bacteria in the tropics. CONCLUSIONS : These different components of honey bees’ biotic niche support the latitudinal biotic interaction hypothesis for actively-chosen interactions, but are more consistent with neutral theory (assuming greater bacterial richness in the tropics) for unintentional interactions.
In memory of Sue Nicolson
(NISC (Pty) Ltd and Informa UK Limited (trading as Taylor and Francis Group), 2024-10) McKechnie, Andrew E.; Crewe, Robin M.; Pirk, Christian Walter Werner; Human, Hannelie; Scholtz, Clarke H.; andrew.mckechnie@up.ac.za
With the passing of Professor Sue Nicolson on 27 April 2023, South Africa’s zoological community lost a respected and internationally acclaimed leader in evolutionary and ecological physiology. Sue was born in Dargaville, New Zealand in 1950 and earned a PhD in insect physiology from the University of Cambridge before moving to the University of Cape Town (UCT) in 1978. After initially being employed as a research assistant to pioneering desert biologist Professor Gideon Louw, Sue was appointed as a senior lecturer in 1990. The UCT Department of Zoology remained her academic home until the end of 2000, when she moved to the University of Pretoria’s (UP) Department of Zoology and Entomology.
Volatile odours reflect breeding status but not social group membership in captive Damaraland mole-rats
(Elsevier, 2025-04) Nichols, Hazel J.; Caspers, Barbara A.; Arbuckle, Kevin; Bennett, Nigel Charles; Hoffman, Joseph I.
In mammals, olfaction plays a key role in social behaviour, for example, in identifying mating opportunities and potential rivals. However, we still have a limited understanding of how social information is encoded in animal odours, including the social determinants of chemical similarity and diversity. Here, we used gas chromatography to analyse the chemical composition of swabs taken from the facial and anogenital regions of Damaraland mole-rats, Fukomys damarensis, a highly social subterranean mammal that relies almost exclusively on olfactory and tactile social cues. We found no sign of individual identity across the two body areas sampled; samples from the facial region and samples of the anogenital region from the same individual were not similar to each other, suggesting that these regions carry different information. However, chemical profiles varied significantly by sex and breeding status; female breeders differed from nonbreeders in their anogenital profiles and had higher chemical diversity in their facial profiles compared with both males and nonbreeders. Interestingly, we found no signals of social group identity. Instead, individual identity may be conveyed through signature mixes that are learned through frequent contact, rather than through specific odours associated with genetic kinship or social group membership. Our results highlight the complexity of chemical communication systems in social species and suggest that signals of group level identity are not necessary for behavioural responses based on group membership.
Local nutrient addition drives plant diversity losses but not biotic homogenization in global grasslands
(Nature Research, 2025-05) Chen, Qingqing; Blowes, Shane A.; Harpole, W. Stanley; Ladouceur, Emma; Borer, Elizabeth T.; Macdougall, Andrew S.; Martina, Jason P.; Bakker, Jonathan D.; Tognetti, Pedro M.; Seabloom, Eric W.; Daleo, Pedro; Power, Sally; Roscher, Christiane; Adler, Peter B.; Donohue, Ian; Wheeler, George; Stevens, Carly; Veen, G.F. Ciska; Risch, Anita C.; Wardle, Glenda M.; Hautier, Yann; Estrada, Catalina; Hersch-Green, Erika; Niu, Yujie; Peri, Pablo L.; Eskelinen, Anu; Gruner, Daniel S.; Venterink, Harry Olde; D’Antonio, Carla; Cadotte, Marc W.; Haider, Sylvia; Eisenhauer, Nico; Catford, Jane; Virtanen, Risto; Morgan, John W.; Tedder, Michelle; Bagchi, Sumanta; Caldeira, Maria C.; Bugalho, Miguel N.; Knops, Johannes M.H.; Dickman, Chris R.; Hagenah, Nicole; Jentsch, Anke; Macek, Petr; Osborne, Brooke B.; Laanisto, Lauri; Chase, Jonathan M.
Nutrient enrichment typically causes local plant diversity declines. A common but untested expectation is that nutrient enrichment also reduces variation in nutrient conditions among localities and selects for a smaller pool of species, causing greater diversity declines at larger than local scales and thus biotic homogenization. Here we apply a framework that links changes in species richness across scales to changes in the numbers of spatially restricted and widespread species for a standardized nutrient addition experiment across 72 grasslands on six continents. Overall, we find proportionally similar species loss at local and larger scales, suggesting similar declines of spatially restricted and widespread species, and no biotic homogenization after 4 years and up to 14 years of treatment. These patterns of diversity changes are generally consistent across species groups. Thus, nutrient enrichment poses threats to plant diversity, including for widespread species that are often critical for ecosystem functions.
Filling the gaps : herpetological checklist of Mayombe National Park and Cabinda Province (Angola) shed light on one of the most unexplored74 corners of tropical Central Africa
(Taylor and Francis, 2025) Lobon-Rovira, Javier; Baptista, Ninda L.; Clark, Tyron; Verburgt, Luke; Jongsma, Greg; Conradie, Werner; Verissimo, Luis; Vaz Pinto, Pedro
The global environmental crisis has reinforced the importance of improving the documentation of the geographical distributions of extant species. With this aim, species inventories of specific locations or regions are a high priority, especially so in poorly explored areas. Cabinda Province, an Angolan enclave located between the Republic of Congo and the Democratic Republic of the Congo (DRC), represents one of the most enigmatic and poorly explored areas in Africa. No detailed species inventories within its protected areas (namely, Mayombe National Park) exist. Furthermore, this region presents some of the better preserved remanent of primary moist rainforest in West Africa. Although these forests are severely threatened by logging and by the rapid social growth in the area. Therefore, we provide here the first herpetological checklist of Mayombe National Park and Cabinda Province, Angola, to shed light on this underexplored corner of Africa. To obtain the most accurate species identification, we performed detailed morphological examinations and DNA barcoding identifications. As a result, we recorded a total of 76 species of amphibians and reptiles in the area, including four new genera, 19 new distribution records for Angola, and 13 candidate species. This work also provides novel topotypic genetic material from three reptile species (i.e., Agama congica, Panaspis cabindae and Atractaspis congica), that may contribute to revise and solve taxonomic inconsistencies in these different groups. Finally, we identified areas of high species richness, as well as areas with a high number of habitat specialists, thus indicating species more vulnerable to extinction. Therefore, our study allowed us to identify areas that are of special interest for conservation of reptiles and amphibians, primarily focus on species vulnerable to extinction, but also to identify some knowledge gaps that still need further investigation. To conclude, this work not only contributes to an improved understanding of Angolan herpetofauna, but also highlights the importance of the western slope of Central Africa as an important biodiversity hotspot, centre of endemism and potential source of diversification for this group of land vertebrates.

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