Drought patterns: their spatiotemporal variability and impacts on maize production in Limpopo province, South Africa.

Due to global climate change, droughts are likely to become more frequent and more severe in many regions such as in South Africa. In Limpopo, observed high climate variability and projected future climate change will likely increase future maize production risks. This paper evaluates drought patterns in Limpopo at two representative sites. We studied how drought patterns are projected to change under future climatic conditions as an important step in identifying adaptation measures (e.g., breeding maize ideotypes resilient to future conditions). Thirty-year time horizons were analyzed, considering three emission scenarios and five global climate models. We applied the WOFOST crop model to simulate maize crop growth and yield formation over South Africa's summer season. We considered three different crop emergence dates. Drought indices indicated that mainly in the scenario SSP5-8.5 (2051-2080), Univen and Syferkuil will experience worsened drought conditions (DC) in the future. Maize yield tends to decline and future changes in the emergence date seem to impact yield significantly. A possible alternative is to delay sowing date to November or December to reduce the potential yield losses. The grain filling period tends to decrease in the future, and a decrease in the duration of the growth cycle is very likely. Combinations of changed sowing time with more drought tolerant maize cultivars having a longer post-anthesis phase will likely reduce the potential negative impact of climate change on maize.

Thermal tolerance responses of the two-spotted stink bug, Bathycoelia distincta (Hemiptera: Pentatomidae), vary with life stage and the sex of adults.

Temperature tolerance is an essential component of insect fitness, and its understanding can provide a predictive framework for their distribution and abundance. The two-spotted stink bug, Bathycoelia distincta Distant, is a significant pest of macadamia. The main goal of this study was to investigate the thermal tolerance of B. distincta across different life stages. Thermal tolerance indices investigated included critical thermal maximum (CTmax), critical thermal minimum (CTmin), effects of acclimation on CTmax and CTmin at 20, 25, and 30 °C, and rapid heat hardening (RHH), and rapid cold hardening (RCH). The Kruskal-Wallis test was used to explore the effects of life stage and acclimation on CTmax and CTmin and Generalized Linear Models (GLM) for the probability of survival after pre-exposure to RHH at 41 °C for 2 h and RCH at -8 °C for 2 h. CTmax and CTmin varied significantly between life stages at all acclimation temperatures, but CTmin (3.5 °C) varied more than CTmax (2.1 °C). Higher acclimation temperatures resulted in larger variations between life stages for both CTmax and CTmin. A significant acclimation response was observed for the CTmax of instar 2 (1.7 °C) and CTmin of females (2.7 °C) across acclimation temperatures (20-30 °C). Pre-exposure significantly improved the heat and cold survival probability of instar 2 and the cold survival probability of instar 3 and males. The response between life stages was more variable in RCH than in RHH. Instar 2 appeared to be the most thermally plastic life stage of B. distincta. These results suggest that the thermal plastic traits of B. distincta life stages may enable this pest to survive in temperature regimes under the ongoing climate change, with early life stages (except for instar 2) more temperature sensitive than later life stages.

Thermoregulatory traits combine with range shifts to alter the future of montane ant assemblages.

Predicting and understanding the biological response to future climate change is a pressing challenge for humanity. In the 21st century, many species will move into higher latitudes and higher elevations as the climate warms. In addition, the relative abundances of species within local assemblages are likely to change. Both effects have implications for how ecosystems function. Few biodiversity forecasts, however, take account of both shifting ranges and changing abundances. We provide a novel analysis predicting the potential changes to assemblage-level relative abundances in the 21st century. We use an established relationship linking ant abundance and their colour and size traits to temperature and UV-B to predict future abundance changes. We also predict future temperature driven range shifts and use these to alter the available species pool for our trait-mediated abundance predictions. We do this across three continents under a low greenhouse gas emissions scenario (RCP2.6) and a business-as-usual scenario (RCP8.5). Under RCP2.6, predicted changes to ant assemblages by 2100 are moderate. On average, species richness will increase by 26%, while species composition and relative abundance structure will be 26% and 30% different, respectively, compared with modern assemblages. Under RCP8.5, however, highland assemblages face almost a tripling of species richness and compositional and relative abundance changes of 66% and 77%. Critically, we predict that future assemblages could be reorganized in terms of which species are common and which are rare: future highland assemblages will not simply comprise upslope shifts of modern lowland assemblages. These forecasts reveal the potential for radical change to montane ant assemblages by the end of the 21st century if temperature increases continue. Our results highlight the importance of incorporating trait-environment relationships into future biodiversity predictions. Looking forward, the major challenge is to understand how ecosystem processes will respond to compositional and relative abundance changes.

The Effects of Temperature on the Development and Survival of Bathycoelia distincta (Hemiptera: Pentatomidae), a Significant Pest of Macadamia in South Africa.

Temperature is the most influential condition affecting insect development and population dynamics. Understanding its impact and other important factors, such as diet, could provide fine-scale predictions of species abundance and distribution in space and time. The two-spotted stink bug, Bathycoelia distincta Distant (Hemiptera: Pentatomidae), is a significant pest of macadamia in South Africa for which limited information on developmental biology exists. Here, for the first time, variations in key developmental parameters of the B. distincta biology were studied systematically. The developmental duration, survival rate, development rate, lower developmental threshold (Tmin), optimum developmental threshold (Topt), upper developmental threshold (Tmax), and thermal constant were quantified for each developmental stage of B. distincta. In addition, the effect of diet (macadamia nut and sweetcorn) on the developmental duration and survival rate were quantified. This study was conducted at five constant temperatures (18, 21, 22, 25, and 29 °C) with relative humidity (RH) variations. The developmental duration from egg to adult decreased significantly with increased temperature: 21 °C (±60 days) to 29 °C (±32 days). The survival rate was significantly different for instar 2 between temperatures. Nymphs (instars 2 and 4) developed faster on the sweetcorn diet than on a macadamia diet, but the total developmental time did not differ significantly between the diets. Development from egg to adult required 783 degree days (DD), with a Tmin of 13.5 °C, Topt of 29.5 °C, and Tmax of 38 °C. Ongoing global warming will increase the population growth of B. distincta through increased development rate, resulting in more damage to macadamia nuts. Understanding the developmental biology and thresholds for the DD model of B. distincta is fundamental for predicting its phenology and outbreaks in macadamia orchards.

Redescriptions of poorly known species of jumping spiders (Araneae: Salticidae) from South Africa and Namibia.

The following seven species of southern African Salticidae, known only from type specimens or one sex, and last described in the early 20th century, are redescribed: Baryphas ahenus Simon, 1902, Brancus muticus Simon, 1902, Euophrys quadrispinosa Lawrence, 1927, Evarcha natalica Simon, 1902, Mogrus macrocephalus Lawrence, 1927, Thyene damarensis Lawrence, 1927 and Thyene bilineata Lawrence, 1927. Two new synonyms are proposed, Thyene damarensis Lawrence, 1927 syn. n. with Hyllus dotatus (Peckham et Peckham, 1903) and Thyene bilineata striatipes Lawrence, 1927 syn. n. with T bilineata Lawrence, 1927. One new combination is proposed, Thyenula natalica comb. n. (ex Evarcha). Leetotypes for Baryphas ahenus Simon, 1902 and Thyene bilineata Lawrence, 1927 are designated. The female of Brancus muticus Simon, 1902 is described for the first time.

Further notes on the Afrotropical genus Festucula Simon, 1901 (Araneae, Salticidae).

Notes on four Festucula species are provided. One species, F.botswanasp. nov., is described as new to science (♀, Botswana). The name F.monticola is revalidated and the male of this species is assigned. The female of F.lawrencei is described for the first time. A new record of F.leroyae is provided.

Broad aggressive interactions among African carnivores suggest intraguild killing is driven by more than competition.

Theory on intraguild killing (IGK) is central to mammalian carnivore community ecology and top-down ecosystem regulation. Yet, the cryptic nature of IGK hinders empirical evaluations. Using a novel data source - online photographs of interspecific aggression between African carnivores - we revisited existing predictions about the extent and drivers of IGK. Compared with seminal reviews, our constructed IGK network yielded 10 more species and nearly twice as many interactions. The extent of interactions increased 37% when considering intraguild aggression (direct attack) as a precursor of killing events. We show that IGK occurs over a wider range of body-mass ratios than predicted by standing competition-based views, with highly asymmetrical interactions being pervasive. Evidence that large species, particularly hypercarnivore felids, target sympatric carnivores with a wide range of body sizes suggests that current IGK theory is incomplete, underestimating alternative competition pathways and the role of predatory and incidental killing. Our findings reinforce the potential for IGK-mediated cascades in species-rich assemblages and community-wide suppressive effects of large carnivores.

Repeated surveying over 6 years reveals that fine-scale habitat variables are key to tropical mountain ant assemblage composition and functional diversity.

High-altitude-adapted ectotherms can escape competition from dominant species by tolerating low temperatures at cooler elevations, but climate change is eroding such advantages. Studies evaluating broad-scale impacts of global change for high-altitude organisms often overlook the mitigating role of biotic factors. Yet, at fine spatial-scales, vegetation-associated microclimates provide refuges from climatic extremes. Using one of the largest standardised data sets collected to date, we tested how ant species composition and functional diversity (i.e., the range and value of species traits found within assemblages) respond to large-scale abiotic factors (altitude, aspect), and fine-scale factors (vegetation, soil structure) along an elevational gradient in tropical Africa. Altitude emerged as the principal factor explaining species composition. Analysis of nestedness and turnover components of beta diversity indicated that ant assemblages are specific to each elevation, so species are not filtered out but replaced with new species as elevation increases. Similarity of assemblages over time (assessed using beta decay) did not change significantly at low and mid elevations but declined at the highest elevations. Assemblages also differed between northern and southern mountain aspects, although at highest elevations, composition was restricted to a set of species found on both aspects. Functional diversity was not explained by large scale variables like elevation, but by factors associated with elevation that operate at fine scales (i.e., temperature and habitat structure). Our findings highlight the significance of fine-scale variables in predicting organisms' responses to changing temperature, offering management possibilities that might dilute climate change impacts, and caution when predicting assemblage responses using climate models, alone.

Revision of the Afrotropical crab-spider genus Parabomis Kulczynski, 1901 (Araneae: Thomisidae).

The Afrotropical spider genus Parabomis Kulczynski, 1901 is revised. Members of Parabomis are some of the smallest thomisids known, and occur from Eritrea in the north of Africa to South Africa in the south, but are absent from Madagascar. Prior to this study, three species were known, namely P. levanderi Kulczynski, 1901 (Eritrea, ♂), P. martini Lessert, 1919 (Tanzania, ♂♀) and P. anabensis Lawrence, 1928 (Namibia, ♀). Parabomis anabensis sp. nov. is here recognized as a junior synonym of P. martini and four new species are described: P. elsae sp. nov. from South Africa (♂♀), P. megae sp. nov. from Zimbabwe (♂♀), P. pilosus sp. nov. from Botswana (♂♀) and P. wandae sp. nov. from Ghana (♂♀). A key to the six species is provided. The monotypic Afrotropical genus Felsina Simon, 1895, only known from its type species, F. granulum Simon, 1895, resembles Parabomis closely is known only from juveniles.

The role of hydro-environmental factors in Mayfly (Ephemeroptera, Insecta) community structure: Identifying threshold responses.

Freshwater organisms are threatened by changes in stream flow and water temperature regimes due to global climate change and anthropogenic activities. Threats include the disappearance of narrow-tolerance species and loss of favorable thermal conditions for cold-adapted organisms. Mayflies are an abundant and diverse indicator of river health that performs important functional roles. The relative importance of key hydro-environmental factors such as water temperature and flow volumes in structuring these communities has rarely been explored in the tropical regions of Africa. Here, we investigate the response of mayfly species diversity to these factors in the Luvuvhu catchment, a strategic water source area in the arid northeastern region of South Africa. Mayfly larvae were sampled monthly in stones-in-current biotopes across 23 sites over a one-year period. The relationship between these environmental drivers and mayfly diversity was modeled using linear mixed effects models (LMMs) and a model-based multivariate approach. Threshold Indicator Taxa Analysis (TITAN) was used to model the response of mayfly species to important gradients and identify thresholds of change. Site-specific characteristic were the most important predictor of mayfly diversity, and there was considerable variation over time, with mayfly diversity peaking during winter. Along this, gradient temperature was the best predictor of assemblage structure, with five out of six reliable indicator species being cold-adapted, and a community threshold response at 19°C. Results support laboratory-based thresholds of temperature for mayfly species survival and development, extending empirical evidence to include field-based observations. Increased global (climate change) and local (riparian vegetation removal, impoundments) changes are predicted to have negative impacts on mayfly diversity and ultimately on ecosystem function.

Globally distributed occurrences utilised in 200 spider species conservation profiles (Arachnida, Araneae).

BACKGROUND: Data on 200 species of spiders were collected to assess the global threat status of the group worldwide. To supplement existing digital occurrence records from GBIF, a dataset of new occurrence records was compiled for all species using published literature or online sources, from which geographic coordinates were extracted or interpreted from locality description data. NEW INFORMATION: A total of 5,104 occurrence records were obtained, of which 2,378 were from literature or online sources other than GBIF. Of these, 2,308 had coordinate data. Reporting years ranged from 1834 to 2017. Most records were from North America and Europe, with Brazil, China, India and Australia also well represented.

Species conservation profiles of a random sample of world spiders III: Oecobiidae to Salticidae.

BACKGROUND: The IUCN Red List of Threatened Species is the most widely used information source on the extinction risk of species. One of the uses of the Red List is to evaluate and monitor the state of biodiversity and a possible approach for this purpose is the Red List Index (RLI). For many taxa, mainly hyperdiverse groups, it is not possible within available resources to assess all known species. In such cases, a random sample of species might be selected for assessment and the results derived from it extrapolated for the entire group - the Sampled Red List Index (SRLI). The current contribution is the third in four papers that will constitute the baseline of a future spider SRLI encompassing 200 species distributed across the world. NEW INFORMATION: A sample of 200 species of spiders were randomly selected from the World Spider Catalogue, an updated global database containing all recognized species names for the group. The 200 selected species where divided taxonomically at the family level, and the familes were ordered alphabetically. In this publication, we present the conservation profiles of 58 species belonging to the famillies alphabetically arranged between Oecobiidae and Salticidae, which encompassed Oecobiidae, Oonopidae, Orsolobidae, Oxyopidae, Palpimanidae, Philodromidae, Pholcidae, Pisauridae, Prodidomidae and Salticidae.

Species conservation profiles of a random sample of world spiders IV: Scytodidae to Zoropsidae.

BACKGROUND: The IUCN Red List of Threatened Species is the most widely used information source on the extinction risk of species. One of the uses of the Red List is to evaluate and monitor the state of biodiversity and a possible approach for this purpose is the Red List Index (RLI). For many taxa, mainly hyperdiverse groups, it is not possible within available resources to assess all known species. In such cases, a random sample of species might be selected for assessment and the results derived from it extrapolated for the entire group - the Sampled Red List Index (SRLI). The current contribution is the final in four papers that will constitute the baseline of a future spider SRLI encompassing 200 species distributed across the world. NEW INFORMATION: A sample of 200 species of spiders were randomly selected from the World Spider Catalogue, an updated global database containing all recognised species names for the group. The selected species were classified taxonomically at the family level and the familes were ordered alphabetically. In this publication, we present the conservation profiles of 50 species belonging to the families alphabetically arranged between Scytodidae and Zoropsidae, which encompassed Scytodidae, Selenopidae, Sicariidae, Sparassidae, Tetrablemmidae, Tetragnathidae, Theraphosidae, Theridiidae, Theridiosomatidae, Thomisidae, Trochanteriidae, Zodariidae and Zoropsidae.

Species conservation profiles of a random sample of world spiders II: Gnaphosidae to Nemesiidae.

BACKGROUND: The IUCN Red List of Threatened Species is the most widely used information source on the extinction risk of species. One of the uses of the Red List is to evaluate and monitor the state of biodiversity and a possible approach for this purpose is the Red List Index (RLI). For many taxa, mainly hyperdiverse groups, it is not possible within available resources to assess all known species. In such cases, a random sample of species might be selected for assessment and the results derived from it extrapolated for the entire group - the Sampled Red List Index (SRLI). The current contribution is the second in four papers that will constitute the baseline of a future spider SRLI encompassing 200 species distributed across the world. NEW INFORMATION: A sample of 200 species of spiders were randomly selected from the World Spider Catalogue, an updated global database containing all recognised species names for the group. The 200 selected species where divided taxonomically at the family level and the familes were ordered alphabetically. In this publication, we present the conservation profiles of 45 species belonging to the families alphabetically arranged between Gnaphosidae and Nemesiidae, which encompassed Gnaphosidae, Idiopidae, Linyphiidae, Liocranidae, Lycosidae, Micropholcommatidae, Mysmenidae and Nemesiidae.

Species conservation profiles of a random sample of world spiders I: Agelenidae to Filistatidae.

BACKGROUND: The IUCN Red List of Threatened Species is the most widely used information source on the extinction risk of species. One of the uses of the Red List is to evaluate and monitor the state of biodiversity and a possible approach for this purpose is the Red List Index (RLI). For many taxa, mainly hyperdiverse groups, it is not possible within available resources to assess all known species. In such cases, a random sample of species might be selected for assessment and the results derived from it extrapolated for the entire group - the Sampled Red List Index (SRLI). With the current contribution and the three following papers, we intend to create the first point in time of a future spider SRLI encompassing 200 species distributed across the world. NEW INFORMATION: A sample of 200 species of spiders were randomly selected from the World Spider Catalogue, an updated global database containing all recognised species names for the group. The 200 selected species where divided taxonomically at the family level and the familes were ordered alphabetically. In this publication, we present the conservation profiles of 46 species belonging to the famillies alphabetically arranged between Agelenidae and Filistatidae, which encompassed Agelenidae, Amaurobiidae, Anyphaenidae, Araneidae, Archaeidae, Barychelidae, Clubionidae, Corinnidae, Ctenidae, Ctenizidae, Cyatholipidae, Dictynidae, Dysderidae, Eresidae and Filistatidae.

Animal taxa contrast in their scale-dependent responses to land use change in rural Africa.

Human-dominated landscapes comprise the bulk of the world's terrestrial surface and Africa is predicted to experience the largest relative increase over the next century. A multi-scale approach is required to identify processes that maintain diversity in these landscapes. Here we identify scales at which animal diversity responds by partitioning regional diversity in a rural African agro-ecosystem between one temporal and four spatial scales. Human land use practices are the main driver of diversity in all seven animal assemblages considered, with medium sized mammals and birds most affected. Even the least affected taxa, bats and non-volant small mammals (rodents), responded with increased abundance in settlements and agricultural sites respectively. Regional turnover was important to invertebrate taxa and their response to human land use was intermediate between that of the vertebrate extremes. Local scale (< 300 m) heterogeneity was the next most important level for all taxa, highlighting the importance of fine scale processes for the maintenance of biodiversity. Identifying the triggers of these changes within the context of functional landscapes would provide the context for the long-term sustainability of these rapidly changing landscapes.

The Impact of Human Activities on Microbial Quality of Rivers in the Vhembe District, South Africa.

BACKGROUND: Water quality testing is dictated by microbial agents found at the time of sampling in reference to their acceptable risk levels. Human activities might contaminate valuable water resources and add to the microbial load present in water bodies. Therefore, the effects of human activities on the microbial quality of rivers collected from twelve catchments in the Vhembe District in South Africa were investigated, with samples analyzed for total coliform (TC) and Eschericha coli (E. coli) contents. METHODS: Physical parameters and various human activities were recorded for each sampling site. The Quanti-Tray(®) method was adopted for the assessment of TC and E. coli contents in the rivers over a two-year period. A multiplex polymerase chain (PCR) method was used to characterize the strains of E. coli found. RESULTS: The microbial quality of the rivers was poor with both TC and E. coli contents found to be over acceptable limits set by the South African Department of Water and Sanitation (DWS). No significant difference (p > 0.05) was detected between TC and E. coli risks in dry and wet seasons. All six pathogenic E. coli strains were identified and Enteroaggregative E. coli (EAEC), atypical Enteropathogenic E. coli (a-EPEC) and Enterotoxigenic E. coli (ETEC) were the most prevalent E. coli strains detected (respectively, 87%, 86% and 83%). CONCLUSIONS: The study indicated that contamination in the majority of sampling sites, due to human activities such as car wash, animal grazing and farming, poses health risks to communities using the rivers for various domestic chores. It is therefore recommended that more education by the respective departments is done to avert pollution of rivers and prevent health risks to the communities in the Vhembe District.

Temporal patterns of ant diversity across a mountain with climatically contrasting aspects in the tropics of Africa.

Factors that drive species richness over space and time are still poorly understood and are often context specific. Identifying these drivers for ant diversity has become particularly relevant within the context of contemporary global change events. We report on a long-term bi-annual (wet and dry seasons), standardized sampling of epigeal ants over a five year period on the mesic and arid aspects of an inselberg (Soutpansberg Mountain Range) in the tropics of Africa. We detail seasonal, annual and long-term trends of species density, test the relative contribution of geometric constraints, energy, available area, climate, local environmental variables, time, and space in explaining ant species density patterns through Generalized Linear Mixed Models (GLMM) where replicates were included as random factors to account for temporal pseudo-replication. Seasonal patterns were very variable and we found evidence of decreased seasonal variation in species density with increased elevation. The extent and significance of a decrease in species density with increased elevation varied with season. Annual patterns point to an increase in ant diversity over time. Ant density patterns were positively correlated with mean monthly temperature but geometric constraints dominated model performance while soil characteristics were minor correlates. These drivers and correlates accounted for all the spatio-temporal variability in the database. Ant diversity was therefore mainly determined by geometric constraints and temperature while soil characteristics (clay and carbon content) accounted for smaller but significant amounts of variation. This study documents the role of season, elevation and their interaction in affecting ant species densities while highlighting the importance of neutral processes and temperature in driving these patterns.