Department of Conservation Ecology and Entomology

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Acoustic monitoring and response of katydids (Orthoptera: Tettigoniidae) to the landscape mosaic in a Biosphere Reserve
(Stellenbosch : Stellenbosch University, 2017-03) Thompson, Aileen Celeste; Samways, Michael J.; Bazelet, Corinna S.; Stellenbosch University. Faculty of AgriSciences. Dept. of Conservation Ecology and Entomology.
ENGLISH SUMMARY: A charismatic group within the Orthoptera, katydids can be found in a variety of habitat types world-wide due to their excellent bark and leaf mimicry skills. Most male katydids produce species-specific calls to attract female mates. If katydids, like their close relatives the grasshoppers, can function as effective biological indicators, then acoustic monitoring of katydid songs may result in a novel and non-invasive method to rapidly assess local biodiversity. Furthermore, information regarding threat statuses, distributions and life history traits can be inferred for all South African katydid species, leading to the development of a Katydid Biotic Index (KBI) based on the highly effective Dragonfly Biotic Index. If proven effective, the KBI would allow for biodiversity assessments to account for detailed aspects of katydid species composition in addition to the diversity measures normally utilized for biodiversity assessment (e.g. species richness and abundance). In this thesis, I provide the first steps towards determining whether the KBI could be an effective assessment technique. First I assess the utility of the KBI at a coarse-scale by determining its ability to identify regions of high conservation priority. Secondly, I conduct a fine scale study to determine the response of the katydid assemblage to habitat quality. And lastly, the first two aims are combined to determine whether the KBI is an appropriate method to assess habitat quality at a fine-scale. In Chapter 2, by using a subset of museum records, I investigate the distribution of the katydids within the Cape Floristic Region (CFR), a global biodiversity hotspot. The katydids found within the CFR follow the same trends with regards to threat status, endemism and life history traits to the overall South African katydid assemblage. The KBI assessment method was able to select, at this coarse-scale, the ecosystems of conservation priority. For Chapters 3 and 4, the Kogelberg Biosphere Reserve (KBR) was selected as a study area as it allowed for the acoustic monitoring and direct comparison of katydid assemblages and responses across the core, buffer and transition zones through the use of passive recordings. In Chapter 3 I found that the katydids of the KBR are not complementary across the zones. However, they respond positively in terms of abundance to measured habitat quality when the entire assemblage is considered. In Chapter 4 I found that katydids responded towards coarse-scale habitat quality and they were not as sensitive towards habitat change as was expected. By including abundances of the katydid species in to the KBI calculations, the sensitivity of the KBI as an assessment method was improved. For this reason, katydids in the fynbos biome are likely to not be effective indicators of habitat change on a small scale, likely due to the surprisingly low diversity of katydid species in the KBR. However, if the KBI were to be tested out in forest patches or areas with higher diversity, the KBI may prove more promising. For these reasons, a rapid assessment technique based on the KBI is likely to be more appropriate for some habitat types over others.
Grasshoppers of azonal riparian corridors and their response to land transformation in the Cape Floristic Region
(Stellenbosch : Stellenbosch University, 2016-03) Pronk, Bianca Mignon; Samways, Michael J.; Pryke, James S.; Bazelet, Corinna S.; Stellenbosch University. Faculty of Agrisciences. Dept. of Conservation Ecology and Entomology.
ENGLISH ABSTRACT: The Cape Floristic Region (CFR) is a global biodiversity hotspot with high levels of endemism across many taxa, including Orthoptera. Azonal vegetation, a much forgotten component of the CFR, is a unique vegetation type that forms part of the riparian corridor. This is a complex, unique and diverse ecosystem with high levels of local biodiversity that connects the aquatic and terrestrial realms. The riparian corridor is highly disturbed through anthropogenic activities and invasion by alien vegetation causing deterioration of riparian corridors. Most natural riparian corridors are now confined to the mountainous slopes and higher elevations. Grasshopper assemblages are good bioindicators of environmental change and habitat deterioration. In response to this I determined the grasshopper assemblage which characterizes the natural riparian and adjacent terrestrial zone and their dispersion across the two zones. I also investigated how grasshoppers respond to riparian corridor disturbances (land transformation) and if they are viable candidates for bioindication of riparian corridors. In Chapter 2 I investigated the ecology of grasshoppers (Orthoptera: Acridoidea) within a non-biome specific natural riparian zone along an important river in the CFR (Lourens River). Grasshopper sampling took place in the natural riparian and terrestrial zones along seven sampling units (SU‟s) that were 25 m in length and 35 m wide, in both the riparian and terrestrial zones. The riparian sites were along the river in the riparian corridor whereas the terrestrial sites were farther away. I did find a significant difference between the natural riparian and terrestrial grasshopper assemblages, but I indicated that grasshopper abundance and species richness may be more associated with the riparian vegetation. In Chapter 3, I investigated how grasshoppers respond to land transformation along the riparian corridor of an important river in the CFR (Lourens River), whilst investigating the possibility of grasshoppers as bioindicators. Grasshopper sampling took place in different land use types (LUTs) (natural, agricultural, cleared of invasive alien-trees, invaded by alien-trees and an urbanized riparian area) along the riparian corridor. Each LUT had seven SU‟s per site where grasshopper sampling took place (as per Chapter 2). I found that grasshopper diversity is significantly influenced by the different LUTs and no CFR endemic grasshoppers were present within the invaded or urbanized riparian area. I found that the agricultural and cleared riparian areas had the highest abundance of grasshoppers and were most speciose with a great abundance of CFR endemic grasshoppers. I found that the cleared riparian LUTs had the most CFR endemic grasshopper richness and abundance. In general I found that grasshoppers respond to the different LUTs. In conclusion, there exists a riparian grasshopper assemblage in the natural riparian zone of the CFR. Conservation is hereby critical in this area as it adds to the biodiversity of the region. Land uses had significant influences on grasshopper assemblages, especially on CFR endemic grasshoppers along the riparian corridor. The conservation and maintenance of the mixture between riparian and fynbos plants are important for grasshopper assemblages and more so for the persistence of CFR endemic grasshoppers. Riparian corridor conservation and maintenance is critical for the maintenance and enhancement of grasshopper biodiversity in a biodiversity hotspot, the CFR.
Integrative taxonomy of the endemic Karoo agile grasshoppers, the Euryphyminae
(Stellenbosch : Stellenbosch University, 2018-03) Tshililo, Precious; Bazelet, Corinna S.; Addison, Pia; Karsten, Minette; Stellenbosch University. Faculty of AgriSciences. Dept. of Conservation Ecology and Entomology.
ENGLISH ABSTRACT: The Euryphyminae are a small, African subfamily of grasshoppers which are not very well known. They are endemic to sub-Saharan Africa and consist of 23 genera, 16 of which have records of occurrence in South Africa. They are extremely agile and difficult to either catch or spot. Morphologically they are adapted to arid regions. The aim of this study was to use an integrative taxonomy approach to fill gaps in knowledge relating to Euryphyminae taxonomy and diversity in the Karoo biome. I collected all Euryphyminae information from literature and digitized 626 museum specimens which had been positively identified. I also conducted two month-long sampling trips and collected 624 specimens of Euryphyminae in thirty sites across the southern Karoo biome. Utilizing all data at my disposal, I conducted the first taxonomic review of South African Euryphyminae, investigated morphological and molecular variation within one speciose genus, Euryphymus, and analysed the ecology and diversity of Euryphyminae across space and time in the Karoo. In Chapter 2, I investigate the relationships among Euryphyminae genera by comparing morphological characters and molecular markers from three genes. I find that while most Eurphyminae genera are monophyletic and well-resolved, the evolutionary history does not comply with easily visible morphological traits. I provide an updated key to males of the Euryphyminae genera. In Chapter 3, I first classify various individual of genus Euryphymus on the basis of their morphology. I then use DNA barcoding to determine the relationship between individuals with various polymorphism. Results show that individuals group into five valid species using the 3% species divergence cutoff which is most commonly used for insect phylogenetics. Of these five species, some may be new to science and may require species description. This study shows that variation among and within Eurypyhminae genera is very high and that morphology alone may not be sufficient to differentiate among species. Finally, in Chapter 4, I investigate species richness, abundance and species composition of the Euryphyminae across space and time. I find that there are at least two distinct peaks of Euryphyminae abundance containing different species. Futhermore, most Euryphyminae species seem to be localized to a particular place and time, as most Karoo sites were dominated by one Euryphyminae species at a particular time, but this species composition turned over with the different seasons. This ecology seems to be closely tied to the arid ecosystem which Euryphyminae is specially adapted to utilize. As the first ever in-depth study on Euryphyminae, this study reveals that Euryphyminae are diverse and abundant in the Karoo biome. There may be many more as yet undiscovered species, and many of the known genera require taxonomic revision. Taxonomic revision will benefit from utilization of genetic traits. Furthermore, the evolutionary history of the Euryphyminae is not straight-forward and requires investigation to better understand how and when the Euryphyminae became specially adapted to utilize the arid and sparsely inhabited Karoo biome. Results from this study will be analysed in conjunction with results from ten other plant and animal taxa sampled in the same sites through SANBI’s Karoo BioGaps project. As a whole, these data will be used to aid in government decision making for the management and conservation planning of the Karoo, especially as it relates to shale gas exploration or fracking.
Katydid (Orthoptera: Tettigoniidae) bio-ecology in Western Cape vineyards
(Stellenbosch : Stellenbosch University, 2017-12) Doubell, Marce; Addison, Pia; Bazelet, Corinna S.; Terblanche, J. S.; Stellenbosch University. Faculty of Agrisciences. Dept. of Conservation Ecology and Entomology.
ENGLISH ABSTRACT: Many orthopterans are associated with large scale destruction of crops, rangeland and pastures. Plangia graminea (Serville) (Orthoptera: Tettigoniidae) is considered a minor sporadic pest in vineyards of the Western Cape Province, South Africa, and was the focus of this study. In the past few seasons (since 2012) P. graminea appeared to have caused a substantial amount of damage leading to great concern among the wine farmers of the Western Cape Province. Very little was known about the biology and ecology of this species, and no monitoring method was available for this pest. The overall aim of the present study was, therefore, to investigate the biology and ecology of P. graminea in vineyards of the Western Cape to contribute knowledge towards the formulation of a sustainable integrated pest management program, as well as to establish an appropriate monitoring system. No detailed surveys have as yet been undertaken to assess the assemblage structure of katydids in vineyards and to verify their taxonomic status. By conducting a survey in vineyards located in the greater Stellenbosch region of the Western Cape, the identities of the katydid species present and their pest status was determined. A monitoring method was developed by adapting a generic sampling system for monitoring key arthropod pests in vineyards. Due to the perfect camouflage of adult katydids within the vine canopy, surrogate methods for monitoring this pest were investigated. Besides determining the basic biology and ecology of P. graminea within vineyards, aspects of its physiological ecology with implications on its mating behaviour were investigated. Furthermore, natural enemies that could potentially be used as environmentally-friendly biological control agents against this pest were identified. Three Phaneropterinae species were identified, namely P. graminea, Eurycorypha lesnei Chopard and a Phaneroptera species. Due to the similarity between the Plangia and Eurycorypha species, an ID-key was compiled for easy identification by growers. Plangia graminea was found to be the primary katydid pest in vineyards monitored. There was only one generation per year, with an overwintering egg stage. The monitoring of katydid eggs could potentially be used to monitor P. graminea, as eggs were positively and significantly correlated with katydid numbers and could allow early prediction estimates of katydid populations in vineyards. Temperature appeared to be an important environmental factor enhancing population outbreaks, as it influenced katydid development, but could also affect mating success of male katydids. It was found that there was a significant metabolic cost associated with the mating calls of P. graminea males. This study identified two natural control agents that could potentially be incorporated into an integrated pest management program for the control of P. graminea, namely hymenopteran egg parasitoids and an entomopathogenic fungus. The outcomes of this study aim towards the development of a practical, sustainable and environmentally-friendly integrated pest management program. Future research should focus on validating a monitoring method in the field, establishing an economic threshold, testing the efficacy of entomopathogenic fungi in the laboratory and in the field, and investigating the mechanisms involved in habitat preferences of hymenopteran egg parasitoids.
Recovery of vegetation and bees after removal of pine forests by fire in the Limietberg region of the Cape Floristic Region biodiversity hotspot
(Stellenbosch : Stellenbosch University, 2015-12) Gardee, Muhammed Nizaar; Samways, Michael J.; Bazelet, Corinna S.; Stellenbosch University. Faculty of Agrisciences. Dept. of Conservation Ecology and Entomology.
ENGLISH ABSTRACT: The present global biodiversity crisis is characterized mostly by loss of species due to habitat destruction but there other major threats – notably invasive alien species. The term “biodiversity hotspot” has been coined to emphasize areas for conservation prioritization – areas that have high biodiversity under threat from habitat destruction, invasive species, etc. The Cape Floristic Region (CFR) in the Western Cape (WC) Province of South Africa has the highest biodiversity of all Mediterranean-type climate regions globally and is classified among global biodiversity hotspots. The CFR, a Mediterranean-type climate heathland with a naturally high fire frequency, faces threat from transformation by development, disturbed (increased) fire frequencies and intensities, and invasive organisms, most notably invasive trees. Such threats disturb keystone species and keystone processes including insect pollinator assemblages and associated insect flower visitation webs and frequencies. Invasive pines are a serious threat to insect flower visitation as pine trees (Pinus spp.) shade out much indigenous vegetation in the CFR. Little is known of their long-term effects on insect flower visitors and vegetation recovery in post-pine restoration and recovery areas after such trees are removed. I investigated the recovery of vegetation and the most important insect pollinator, bees, after the removal of pines by fire and passive recovery in a CFR valley in the Western Cape. In 1999, a wildfire burned much of the WC Limietberg Nature Reserve along with an adjacent pine tree forestry stand - which was then left to recover, providing an ideal opportunity to investigate the enduring effects of pine afforestation in the CFR. In two data chapters, I compared the post-fire passive recovery of vegetation (Chapter 2) and bee diversity (Chapter 4) in areas which had previously been planted with pines vs. those which had contained natural fynbos. To improve on sampling methodology, I conducted an experiment that demonstrated the Observer Effect in bee sampling with a sweep net (Chapter 3), and I developed a novel sampling device (Chapter 5) for insect flower visitors. Sampling of vegetation and bee diversity was conducted in a paired sampling design, where fynbos (Natural) sub-sites were paired with sub-sites which had previously been afforested with pines (Post-Pine Recovery; PPR) and the two sub-sites were separated by a distinct, linear boundary (Natural/PPR boundary). Sampling was conducted along transects parallel to the boundary and extending in both directions from the boundary into the Natural and in the opposite direction into PPR sub-sites. Five transects were positioned at 3, 10, 20, 30, and 40 m from the boundary (Ecotone) and three were positioned at 60, 80, and 100 m from the boundary (Deep). In Chapter 2, I found that natural sub-sites consistently had higher total plant species abundance and species richness than PPR sub-sites. Approximately two thirds of plant species were more abundant in Natural sub-sites than in PPR sub-sites. There was no significant correlation in species richness or abundance with distance from the Natural/PPR boundary. Some genera are cautiously indicated as having lower success in recovery after pine afforestation: Erica spp., Restio spp., Hypodiscus spp. while Helichrysum spp. is also tentatively indicated to recover well in PPR sub-sites. Soil disturbance and concomitant disruption of normal ecosystem functions, including pollination, is indicated as a probable reason for disruption of plant recovery. In Chapter 3, sweep netting methodology was tested for the Observer Effect. A noticeable increase in bee visitation frequency to a common generalist plant species in bloom, Metalasia densa, was correlated with longer waiting periods after I stopped moving indicating the presence of an Observer Effect. This suggests that sweep netting for bees should only be commenced after a waiting period of five minutes during which the sweep netter is motionless. In Chapter 4, using a flight-intercept modified pan trap, I compared bee species richness and bee species abundance across different seasons and in both mass-flowering and sparser flower patches. There was no significant difference in bee species richness between Natural and PPR sub-sites. All bee species, except one complex, were more abundant in Natural sub-sites. Nearly two thirds of all bee species (n=37 of 56) caught with sweep netting and the modified pan trap are undescribed species. Similar to the vegetation, the effects of soil disturbance as a result of decades of pine forest shading and pine forest litterfall followed by an unusually hot pine forest fire are indicated as the most likely reasons for lower bee abundance in PPR sub-sites. This is due to the difficulty associated with viable nest establishment and suitable pollen and nectar forage availability in disturbed areas. In Chapter 5, the newly developed Pan and Flight Intercept Combination (PAFIC) trap’s design, pilot testing, and comparison with the traditional pan trap is discussed. A preliminary test suggests that the PAFIC trap is more efficient (with higher abundance) than the traditional pan trap. In Chapter 6, I discuss the implications of the disturbance of pine forestry and unusual pine fire to plant species and bee species assemblages. Bee-pollination webs in PPR sub-sites are indicated as being substantially simpler than those in Natural areas as well as compositionally different. The recovery of pollination as a keystone process in post pine-afforestation areas faces a substantial challenge given the disturbance to soil that decades of pine afforestation followed by pine forest fire can cause. Some suggestions are made for the restoration of fynbos areas recovering from pine afforestation including a discussion of augmenting re-vegetation measures (fynbos seed dispersal and seedling planting) with methods of restoring of healthy pedogenesis, epigaeic arthropod communities, and fynbos seedbanks.
Response of grasshoppers to the agricultural mosaics of the Cape Floristic Region biodiversity hotspot in South Africa
(Stellenbosch : Stellenbosch University, 2017-03) Adu-Acheampong, Samuel; Samways, Michael J.; Bazelet, Corinna S.; Stellenbosch University. Faculty of AgriSciences. Dept. Conservation Ecology and Entomology.
ENGLISH ABSTRACT: Agricultural production is one of the main drivers of the on-going biodiversity crisis. This has resulted in research on the impact of agriculture on biodiversity being at an all-time high. This is critical given that the world must produce food for the ever-growing human population. This growing demand for food often demands increasing production areas at the expense of protected ones. Such trade-offs can potentially lead to dire consequences on biodiversity and its associated ecosystem function. In an attempt to minimise this potential negative impact, and also to conserve biodiversity and its associated ecosystem function, scientists and producers have developed a system that integrates natural with production patches as part of making agriculture more sustainable. In most instances, decisions on agro-natural schemes for sustainable food production are based on research conducted on larger animals at the expense of smaller ones, especially arthropods, even though they constitute the largest group of animals. If humans are to achieve the aim of producing food to meet the growing demand at minimum cost to the environment and biodiversity, studies on smaller animals such as insects, which constitute more than 75% of all animals, and are also major contributors of terrestrial ecosystem function in the terrestrial world, must be considered a high priority. An insect group that has much value for the purpose of designing agro-natural schemes is grasshoppers (Orthoptera, Acridoidea). This is because they show high sensitivity to changes in vegetation type and structure, and have high potential for expressing changes in environmental conditions and vegetation. This is even more important in a biodiversity hotspot which is also known for intensive agricultural production, such as the Cape Floristic Region (CFR). In view of that, I embarked on a study to document the footprint of agricultural production types on biodiversity using grasshoppers as keystone species in four studies making up my four core chapters. Firstly, I compared species richness, abundance, composition, diversity and evenness of grasshoppers among 46 sites in four geographical areas in the CFR. Here, I investigated three land-use types: fynbos, vineyards and deciduous fruit orchards, the main production types in the region. Results showed that grasshopper abundance were significantly higher in vineyards than in fynbos or orchards. Species richness, diversity, and evenness were highest in fynbos followed by vineyards and then orchards. There was overall high species similarity among all three land-use types, with high species assemblage similarities between vineyards and orchards. Species that preferred fynbos were mostly flightless and endemic to the CFR. In the second chapter, grasshopper abundance was studied under agricultural land-use (vineyards) and in natural vegetation (fynbos) across two peak seasons (spring vs. summer). This study aimed at quantifying the level at which different grasshopper species utilise the different aspects of the landscape and how this range of utilisation among species relates to certain species’ traits. My results showed that species traits play a major role in grasshoppers’ ability to move between patches, and which also affects how they utilize various different patches on the landscape. Highly mobile, generalist species are able to utilise more aspects of the landscape. And depending on seasonality, these species will inhabit either vineyards or fynbos aided by their high ability to move between patches. On the other hand, low mobility, specialists lack the ability to move readily between patches, and as a result, they are confined to one or a few patches across the seasons. In the third chapter, I developed species distribution models for four localized, CFR endemic flightless grasshopper species, Euloryma larsenorum and E. lapollai, E. umoja and E. ottei. The first two are associated with fynbos only, while E. umoja and E. ottei, the second two, are both associated with both fynbos and vineyards. I used the Maximum Entropy algorithm, which showed that vegetation type and soil characteristics were the most important environmental factors affecting local distribution of Euloryma species in the CFR. My models also showed that Euloryma species have very narrow, predicted, suitable habitats in the CFR. I also showed that there are no significant differences in the distribution of species associated with fynbos only as well as those associated with both fynbos and vineyards. Lastly, in the fourth chapter, I investigated grasshopper species assemblage composition on three land-uses across the agro-natural mosaic landscape of CFR. This study documented species’ level of occupancy and abundances in relation to their life history traits in order to assess the amount of change occurring on the landscape in the CFR. My results show that very few species, and mostly from Acrididae, dominated the landscape. It also shows that the species that dominated the transformed landscape were generalists. There was also a high correlation between generalists, high to medium mobility and widespread species on one hand, and specialists, low in mobility, and localised species on the other. Conclusions My study shows that protected areas still remain vital for maintaining the full complement of CFR grasshopper species, especially flightless endemics. I also show that highly mobile, generalist species are better adapted to heterogeneous and novel landscapes compared to low mobility specialists. Surprisingly, agricultural production supports a wide variety of species, and hence contributes positively towards grasshopper conservation in the CFR. This study further shows that it is the poorly-mobile, specialist species that are particularly vulnerable to ongoing landscape change as they can only benefit from remnant patches of natural vegetation, unlike the highly mobile generalists which can move around the landscape and benefit both from anthropogenic patches and natural ones. To reduce future biotic erosion and homogenisation, there should be concerted efforts to protect grasshopper groups which occur in low abundance in this biodiversity hotspot.

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