A history of southern African research relevant to forensic entomology
- Williams, Kirstin A, Villet, Martin H
- Authors: Williams, Kirstin A , Villet, Martin H
- Date: 2006
- Language: English
- Type: text , Article
- Identifier: vital:6909 , http://hdl.handle.net/10962/d1011862
- Description: Entomological forensic evidence has been used in southern Africa for decades but explicitly forensic research began in southern Africa only 26 years ago. Although applicable local research has accumulated since 1921, it is scattered in a diverse literature or unpublished. Some overseas research has also touched on local species. This review uses a historical approach to synthesize the southern African literature and to illustrate the cross-disciplinary, opportunistic nature of forensic entomology. Distinct phases of research focused on agriculture (1921-1950), medicine (1952- 1965), ecology (1968-1990) and forensics (1980-2005), but systematics spanned the entire period and tended to be ad hoc. Few scientists were involved, situated at geographically distant locations and with widely disparate research interests. The review concludes with an overview of southern African entomologists who have been involved in medico-legal investigations, and a critical evaluation of the past and future of the discipline locally.
- Full Text:
- Date Issued: 2006
- Authors: Williams, Kirstin A , Villet, Martin H
- Date: 2006
- Language: English
- Type: text , Article
- Identifier: vital:6909 , http://hdl.handle.net/10962/d1011862
- Description: Entomological forensic evidence has been used in southern Africa for decades but explicitly forensic research began in southern Africa only 26 years ago. Although applicable local research has accumulated since 1921, it is scattered in a diverse literature or unpublished. Some overseas research has also touched on local species. This review uses a historical approach to synthesize the southern African literature and to illustrate the cross-disciplinary, opportunistic nature of forensic entomology. Distinct phases of research focused on agriculture (1921-1950), medicine (1952- 1965), ecology (1968-1990) and forensics (1980-2005), but systematics spanned the entire period and tended to be ad hoc. Few scientists were involved, situated at geographically distant locations and with widely disparate research interests. The review concludes with an overview of southern African entomologists who have been involved in medico-legal investigations, and a critical evaluation of the past and future of the discipline locally.
- Full Text:
- Date Issued: 2006
A new and earlier record of Chrysomya megacephala in South Africa, with notes on another exotic species, Calliphora vicina (Diptera Calliphoridae)
- Williams, Kirstin A, Villet, Martin H
- Authors: Williams, Kirstin A , Villet, Martin H
- Date: 2006
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/440710 , vital:73805 , https://hdl.handle.net/10520/EJC84554
- Description: South African records of Chrysomya megacephala and Calliphora vicina are reviewed and plotted on maps. Dispersal routes of these two forensically and medically important blowfly species are discussed. Emphasised is the importance of deposition of voucher material in museum collections.
- Full Text:
- Date Issued: 2006
- Authors: Williams, Kirstin A , Villet, Martin H
- Date: 2006
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/440710 , vital:73805 , https://hdl.handle.net/10520/EJC84554
- Description: South African records of Chrysomya megacephala and Calliphora vicina are reviewed and plotted on maps. Dispersal routes of these two forensically and medically important blowfly species are discussed. Emphasised is the importance of deposition of voucher material in museum collections.
- Full Text:
- Date Issued: 2006
Effects of prophylactic progesterone in decomposing tissues on the development of Chrysomya chloropyga (Wiedeman)(Diptera Calliphoridae)
- Da Silva, C, Villet, Martin H
- Authors: Da Silva, C , Villet, Martin H
- Date: 2006
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/442020 , vital:73950 , https://hdl.handle.net/10520/EJC32654
- Description: Medico-legal forensic entomology is often concerned with the estimation of postmortem intervals (PMI), the time elapsed since the death of a body, by estimating the age of maggots if they are found on a body. These estimates can be complicated by the presence of a variety of drugs that may be present in dead bodies, including steroids such as hydrocortisone (Musvasva et al. 2001).
- Full Text:
- Date Issued: 2006
- Authors: Da Silva, C , Villet, Martin H
- Date: 2006
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/442020 , vital:73950 , https://hdl.handle.net/10520/EJC32654
- Description: Medico-legal forensic entomology is often concerned with the estimation of postmortem intervals (PMI), the time elapsed since the death of a body, by estimating the age of maggots if they are found on a body. These estimates can be complicated by the presence of a variety of drugs that may be present in dead bodies, including steroids such as hydrocortisone (Musvasva et al. 2001).
- Full Text:
- Date Issued: 2006
Karyology of the redfin minnows, genus Pseudobarbus Smith, 1841 (Teleostei: Cyprinidae): one of the evolutionarily tetraploid lineages of South African barbines
- Naran, Daksha, Skelton, Paul H, Villet, Martin H
- Authors: Naran, Daksha , Skelton, Paul H , Villet, Martin H
- Date: 2006
- Language: English
- Type: Article
- Identifier: vital:6770 , http://hdl.handle.net/10962/d1008063
- Description: The karyotypes of six species of Pseudobarbus Smith, 1841, namely P. afer (Peters, 1864), P. asper (Boulenger, 1911), P. burchelli Smith, 1841, P. burgi (Boulenger, 1911), P. phlegethon (Barnard, 1938) and P. tenuis (Barnard, 1938), were examined by conventional Giemsa staining and described. All six karyotypes have 2n = 100 chromosomes, dominated by biarmed chromosomes, as does the only other member of the genus, P. quathlambae (Barnard, 1938). Sex-related intraspecific karyotype variation was not found. The shared chromosome numbers and general similarity of the karyotypes (FN = 186–192) provide a new synapomorphy to support their monophyly, which is already indicated by anatomical and mtDNA markers. Karyotype evolution within the genus has been accompanied by chromosomal inversions and centromeric shifts. Comparison of the diploid number found in Pseudobarbus with other African barbine cyprinines, which have in the region of 2n=50 and lower FNs, suggests a tetraploid evolutionary origin of the genus, possibly by allotetraploidy.
- Full Text:
- Date Issued: 2006
- Authors: Naran, Daksha , Skelton, Paul H , Villet, Martin H
- Date: 2006
- Language: English
- Type: Article
- Identifier: vital:6770 , http://hdl.handle.net/10962/d1008063
- Description: The karyotypes of six species of Pseudobarbus Smith, 1841, namely P. afer (Peters, 1864), P. asper (Boulenger, 1911), P. burchelli Smith, 1841, P. burgi (Boulenger, 1911), P. phlegethon (Barnard, 1938) and P. tenuis (Barnard, 1938), were examined by conventional Giemsa staining and described. All six karyotypes have 2n = 100 chromosomes, dominated by biarmed chromosomes, as does the only other member of the genus, P. quathlambae (Barnard, 1938). Sex-related intraspecific karyotype variation was not found. The shared chromosome numbers and general similarity of the karyotypes (FN = 186–192) provide a new synapomorphy to support their monophyly, which is already indicated by anatomical and mtDNA markers. Karyotype evolution within the genus has been accompanied by chromosomal inversions and centromeric shifts. Comparison of the diploid number found in Pseudobarbus with other African barbine cyprinines, which have in the region of 2n=50 and lower FNs, suggests a tetraploid evolutionary origin of the genus, possibly by allotetraploidy.
- Full Text:
- Date Issued: 2006
Larval development of the carrion-breeding flesh fly, Sarcophaga (Liosarcophaga) tibialis Macquart (Diptera: Sarcophagidae), at constant temperatures
- Villet, Martin H, MacKenzie, Bernard L, Muller, Nikite W J
- Authors: Villet, Martin H , MacKenzie, Bernard L , Muller, Nikite W J
- Date: 2006
- Language: English
- Type: text , Article
- Identifier: vital:7091 , http://hdl.handle.net/10962/d1012422
- Description: Larvae of Sarcophaga (Liosarcophaga) tibialis Macquart were raised on chicken liver under six different constant temperatures. Maximum survival indicated an optimal developmental temperature of near 20°C, while trends in mortality, larval length and larval mass implied that the thermal window for successful development lay between 15°C and 30°C. Using a recently described method to estimate a simple thermal summation model, it was found that the timing of the end of the feeding phase could be estimated by a developmental zero (D0) of 5.2°C (S.E. = 1.21) and a thermal summation constant (K) of 106.4 d°C (S.E. = 8.31) and of the end of the wandering phase by D0 = 4.1°C (S.E. = 0.39) and K = 126.7 d°C (S.E. = 3.28). Published development times at constant temperatures were compiled for 19 other species of flesh flies, and the developmental constants were calculated for six species for which sufficient data were accumulated.
- Full Text:
- Date Issued: 2006
- Authors: Villet, Martin H , MacKenzie, Bernard L , Muller, Nikite W J
- Date: 2006
- Language: English
- Type: text , Article
- Identifier: vital:7091 , http://hdl.handle.net/10962/d1012422
- Description: Larvae of Sarcophaga (Liosarcophaga) tibialis Macquart were raised on chicken liver under six different constant temperatures. Maximum survival indicated an optimal developmental temperature of near 20°C, while trends in mortality, larval length and larval mass implied that the thermal window for successful development lay between 15°C and 30°C. Using a recently described method to estimate a simple thermal summation model, it was found that the timing of the end of the feeding phase could be estimated by a developmental zero (D0) of 5.2°C (S.E. = 1.21) and a thermal summation constant (K) of 106.4 d°C (S.E. = 8.31) and of the end of the wandering phase by D0 = 4.1°C (S.E. = 0.39) and K = 126.7 d°C (S.E. = 3.28). Published development times at constant temperatures were compiled for 19 other species of flesh flies, and the developmental constants were calculated for six species for which sufficient data were accumulated.
- Full Text:
- Date Issued: 2006
Recruitment behaviour in the ponerine ant, Plectroctena mandibularis F. Smith (Hymenoptera: Formicidae)
- Wilkins, K J, Harman, K, Villet, Martin H
- Authors: Wilkins, K J , Harman, K , Villet, Martin H
- Date: 2006
- Language: English
- Type: text , Article
- Identifier: vital:6887 , http://hdl.handle.net/10962/d1011647
- Description: Although workers of Plectroctena mandibularis laid trails with their stings while foraging, the trails appeared to be for individual orientation, because they never recruited nestmates to prey. However, both workers and queens laid trails when recruiting nestmates of either caste to new nest sites. During trail-laying, fluted hairs on the posterior edge of tergite VI were dragged along the ground, presumably applying a pheromone to the substrate. Anatomical and behavioural evidence suggests that pygidial gland secretions moved from the intersegmental pygidial gland between tergites VI and VII into a fingerprint-like, lamellar cuticular reservoir on the pygidium, and from there via the hairs to the substrate. These results suggest that recruitment may be crucial to moving nests but of value only to certain types of foraging, and that recruitment might even have originated in the Formicidae in the context of colony relocation, and then secondarily evolved to assist foraging.
- Full Text:
- Date Issued: 2006
- Authors: Wilkins, K J , Harman, K , Villet, Martin H
- Date: 2006
- Language: English
- Type: text , Article
- Identifier: vital:6887 , http://hdl.handle.net/10962/d1011647
- Description: Although workers of Plectroctena mandibularis laid trails with their stings while foraging, the trails appeared to be for individual orientation, because they never recruited nestmates to prey. However, both workers and queens laid trails when recruiting nestmates of either caste to new nest sites. During trail-laying, fluted hairs on the posterior edge of tergite VI were dragged along the ground, presumably applying a pheromone to the substrate. Anatomical and behavioural evidence suggests that pygidial gland secretions moved from the intersegmental pygidial gland between tergites VI and VII into a fingerprint-like, lamellar cuticular reservoir on the pygidium, and from there via the hairs to the substrate. These results suggest that recruitment may be crucial to moving nests but of value only to certain types of foraging, and that recruitment might even have originated in the Formicidae in the context of colony relocation, and then secondarily evolved to assist foraging.
- Full Text:
- Date Issued: 2006
Sperm morphology in five species of cicadettine cicadas (Hemiptera: Cicadomorpha: Cicadidae)
- Chawanji, A S, Hodgson, Alan N, Villet, Martin H
- Authors: Chawanji, A S , Hodgson, Alan N , Villet, Martin H
- Date: 2006
- Language: English
- Type: Article
- Identifier: vital:6930 , http://hdl.handle.net/10962/d1011948
- Description: Mature spermatozoa from five species of cicadas of the subfamily Cicadettinae (Quintilia wealei, Melampsalta leucoptera, Stagira simplex, Xosopsaltria thunbergi and Monomatapa matoposa) were examined by light and electron microscopy. In each species sperm are elongate, aggregated into organized bundles with their heads embedded in a homogenous matrix to form spermatodesmata, and exhibit polymegaly. The head of the sperm consist of an anteriorly positioned conical acrosome that has a tubular substructure and a deep, posterior invagination that forms the subacrosomal space (eccentrically positioned anteriorly). The acrosome is flattened anteriorly; posteriorly it extends along either side of the nucleus as two tubular processes that gradually decrease in diameter. The filiform nucleus tapers anteriorly and intrudes into the subscrosomal space. Posteriorly the nucleus has a lateral invagination that houses material of the so-called centriolar adjunct. Posterior to the centriolar adjuct and the nucleus are two crystalline mitochondrial derivatives and a centriole, respectively, the latter giving rise to the axoneme, which has a 9 + 9 + 2 arrangement of microtubules. In these respects the sperm are similar to those of platypleurine cicadas. However, some features seem unique to cicadettines, including the structural organization of an enlarged centriolar adjunct and the dimensions of the tails. The enlarged centriolar adjunct has a lamella-like substructure and can be considered a synapomorphic character in the Cicadettinae. It is, therefore, potentially useful in the separation of this subfamily from the Cicadinae. In addition, the great length of the sperm nucleus of long-headed sperm in M. matoposa could be a synapomorphy of this genus and related taphurine and cicadettine species.
- Full Text:
- Date Issued: 2006
- Authors: Chawanji, A S , Hodgson, Alan N , Villet, Martin H
- Date: 2006
- Language: English
- Type: Article
- Identifier: vital:6930 , http://hdl.handle.net/10962/d1011948
- Description: Mature spermatozoa from five species of cicadas of the subfamily Cicadettinae (Quintilia wealei, Melampsalta leucoptera, Stagira simplex, Xosopsaltria thunbergi and Monomatapa matoposa) were examined by light and electron microscopy. In each species sperm are elongate, aggregated into organized bundles with their heads embedded in a homogenous matrix to form spermatodesmata, and exhibit polymegaly. The head of the sperm consist of an anteriorly positioned conical acrosome that has a tubular substructure and a deep, posterior invagination that forms the subacrosomal space (eccentrically positioned anteriorly). The acrosome is flattened anteriorly; posteriorly it extends along either side of the nucleus as two tubular processes that gradually decrease in diameter. The filiform nucleus tapers anteriorly and intrudes into the subscrosomal space. Posteriorly the nucleus has a lateral invagination that houses material of the so-called centriolar adjunct. Posterior to the centriolar adjuct and the nucleus are two crystalline mitochondrial derivatives and a centriole, respectively, the latter giving rise to the axoneme, which has a 9 + 9 + 2 arrangement of microtubules. In these respects the sperm are similar to those of platypleurine cicadas. However, some features seem unique to cicadettines, including the structural organization of an enlarged centriolar adjunct and the dimensions of the tails. The enlarged centriolar adjunct has a lamella-like substructure and can be considered a synapomorphic character in the Cicadettinae. It is, therefore, potentially useful in the separation of this subfamily from the Cicadinae. In addition, the great length of the sperm nucleus of long-headed sperm in M. matoposa could be a synapomorphy of this genus and related taphurine and cicadettine species.
- Full Text:
- Date Issued: 2006
The effect of water hyacinth, Eichhornia crassipes (Martius) SolmsLaubach (Pontederiaceae), on benthic biodiversity in two impoundments on the New Year's River, South Africa
- Midgley, John M, Hill, Martin P, Villet, Martin H
- Authors: Midgley, John M , Hill, Martin P , Villet, Martin H
- Date: 2006
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/442358 , vital:73978 , https://doi.org/10.2989/16085910609503868
- Description: Water hyacinth, Eichhornia crassipes (Martius) Solms-Laubach (Pontederiaceae), forms thick mats that affect water resource utilisation, but little is known about its impacts on biodiversity in aquatic ecosystems. The benthic invertebrate community and algal biomass were sampled under water hyacinth mats and in water hyacinth-free water over a 13-month period, using artificial substrates in New Year's Dam, Eastern Cape Province, South Africa. The number of families per substrate (U = 796.5, P 0.001), number of individuals per substrate (U = 620.5, P 0.001), Shannon-Weiner Diversity Index (U = 1 038, P 0.001), Margalef's Richness index (U = 1 136, P 0.002), Pielou's Evenness Index (U = 1 230, P 0.001) and chlorophyll a (U = 678, P 0.01) were all significantly lower under water hyacinth mats than in water hyacinth-free zones. Similarly, multivariate analyses showed more diversity in invertebrate communities in open water than under water hyacinth. Thus, the control of water hyacinth is important, in order to prevent both ecological and economic impacts of biodiversity loss.
- Full Text:
- Date Issued: 2006
- Authors: Midgley, John M , Hill, Martin P , Villet, Martin H
- Date: 2006
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/442358 , vital:73978 , https://doi.org/10.2989/16085910609503868
- Description: Water hyacinth, Eichhornia crassipes (Martius) Solms-Laubach (Pontederiaceae), forms thick mats that affect water resource utilisation, but little is known about its impacts on biodiversity in aquatic ecosystems. The benthic invertebrate community and algal biomass were sampled under water hyacinth mats and in water hyacinth-free water over a 13-month period, using artificial substrates in New Year's Dam, Eastern Cape Province, South Africa. The number of families per substrate (U = 796.5, P 0.001), number of individuals per substrate (U = 620.5, P 0.001), Shannon-Weiner Diversity Index (U = 1 038, P 0.001), Margalef's Richness index (U = 1 136, P 0.002), Pielou's Evenness Index (U = 1 230, P 0.001) and chlorophyll a (U = 678, P 0.01) were all significantly lower under water hyacinth mats than in water hyacinth-free zones. Similarly, multivariate analyses showed more diversity in invertebrate communities in open water than under water hyacinth. Thus, the control of water hyacinth is important, in order to prevent both ecological and economic impacts of biodiversity loss.
- Full Text:
- Date Issued: 2006
The six-legged flying squad
- Villet, Martin H, Muller, Nikite W J
- Authors: Villet, Martin H , Muller, Nikite W J
- Date: 2006
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/442677 , vital:74020 , https://journals.co.za/doi/pdf/10.10520/AJA1729830X_227
- Description: How do bugs and insects help forensic entomologists to settle disputes and solve crimes? Martin Villet and Nikite Muller explain.
- Full Text:
- Date Issued: 2006
- Authors: Villet, Martin H , Muller, Nikite W J
- Date: 2006
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/442677 , vital:74020 , https://journals.co.za/doi/pdf/10.10520/AJA1729830X_227
- Description: How do bugs and insects help forensic entomologists to settle disputes and solve crimes? Martin Villet and Nikite Muller explain.
- Full Text:
- Date Issued: 2006
Borror and Delong's Introduction to the Study of Insects, 7th edition, C.A. Triplehorn and N.F. Johnson: book review
- Authors: Villet, Martin H
- Date: 2005
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/451655 , vital:75067 , https://hdl.handle.net/10520/EJC32631
- Description: This book is explicitly a teaching text, and has to be evaluated in those terms. There are essentially two extremes to structuring biological curricula: a taxonomic or phylogenetic approach that is interested in the organisms themselves, and a functional approach that uses the organisms as models to illustrate general biological principles.
- Full Text:
- Date Issued: 2005
- Authors: Villet, Martin H
- Date: 2005
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/451655 , vital:75067 , https://hdl.handle.net/10520/EJC32631
- Description: This book is explicitly a teaching text, and has to be evaluated in those terms. There are essentially two extremes to structuring biological curricula: a taxonomic or phylogenetic approach that is interested in the organisms themselves, and a functional approach that uses the organisms as models to illustrate general biological principles.
- Full Text:
- Date Issued: 2005
Influence of grazing by large mammals on the spider community of a Kenyan savanna biome
- Warui, Charles M, Villet, Martin H, Young, T P, Jocqué, R
- Authors: Warui, Charles M , Villet, Martin H , Young, T P , Jocqué, R
- Date: 2005
- Language: English
- Type: Article
- Identifier: vital:6889 , http://hdl.handle.net/10962/d1011649 , http://0-www.bioone.org.wam.seals.ac.za/doi/10.1636/CT05-43.1
- Full Text:
- Date Issued: 2005
- Authors: Warui, Charles M , Villet, Martin H , Young, T P , Jocqué, R
- Date: 2005
- Language: English
- Type: Article
- Identifier: vital:6889 , http://hdl.handle.net/10962/d1011649 , http://0-www.bioone.org.wam.seals.ac.za/doi/10.1636/CT05-43.1
- Full Text:
- Date Issued: 2005
Sperm morphology in four species of African platypleurine cicadas (Hemiptera: Cicadomorpha: Cicadidae)
- Chawanji, A S, Hodgson, Alan N, Villet, Martin H
- Authors: Chawanji, A S , Hodgson, Alan N , Villet, Martin H
- Date: 2005
- Language: English
- Type: Article
- Identifier: vital:6917 , http://hdl.handle.net/10962/d1011880
- Description: Mature spermatozoa from four species of platypleurine cicadas (Albanycada albigera, Azanicada zuluensis, Platypleura capensis and P. hirtipennis) were examined by light and electron microscopy. The filiform sperm have a similar ultrastructure in all species but notable variations were found in sperm dimensions. All species produce more than one discrete length of nucleated, motile sperm, a form of polymorphism termed polymegaly. Polymegaly is expressed in two ways: sperm have bi- or trimodal head and tail lengths. The anterior parts of sperm heads are embedded in an elongate homogenous matrix forming a spermatodesm. The conical acrosome is deeply invaginated posteriorly, and sits on top of the nucleus. The acrosomal contents are differentiated internally with an electron-lucent central medulla and a denser cortex. The homogenously electron-dense nucleus is pointed anteriorly and is generally cylindrical, although posteriorly there is a lateral invagination that extends part-way along the nucleus. This invagination houses fine granular material of the centriolar adjunct. Vesicle-like elements that are associated with both the posterior nucleus and the centriolar adjunct are also found within the invagination. Immediately posterior of and adjoining the centriolar adjunct is a pair of mitochondrial derivatives that are elongated and extend for almost the entire length of the tail. The absence of accessory bodies in cicada sperm suggests that within the Cicadomorpha, the families Cicadidae and Cercopidae are closely affiliated.
- Full Text:
- Date Issued: 2005
- Authors: Chawanji, A S , Hodgson, Alan N , Villet, Martin H
- Date: 2005
- Language: English
- Type: Article
- Identifier: vital:6917 , http://hdl.handle.net/10962/d1011880
- Description: Mature spermatozoa from four species of platypleurine cicadas (Albanycada albigera, Azanicada zuluensis, Platypleura capensis and P. hirtipennis) were examined by light and electron microscopy. The filiform sperm have a similar ultrastructure in all species but notable variations were found in sperm dimensions. All species produce more than one discrete length of nucleated, motile sperm, a form of polymorphism termed polymegaly. Polymegaly is expressed in two ways: sperm have bi- or trimodal head and tail lengths. The anterior parts of sperm heads are embedded in an elongate homogenous matrix forming a spermatodesm. The conical acrosome is deeply invaginated posteriorly, and sits on top of the nucleus. The acrosomal contents are differentiated internally with an electron-lucent central medulla and a denser cortex. The homogenously electron-dense nucleus is pointed anteriorly and is generally cylindrical, although posteriorly there is a lateral invagination that extends part-way along the nucleus. This invagination houses fine granular material of the centriolar adjunct. Vesicle-like elements that are associated with both the posterior nucleus and the centriolar adjunct are also found within the invagination. Immediately posterior of and adjoining the centriolar adjunct is a pair of mitochondrial derivatives that are elongated and extend for almost the entire length of the tail. The absence of accessory bodies in cicada sperm suggests that within the Cicadomorpha, the families Cicadidae and Cercopidae are closely affiliated.
- Full Text:
- Date Issued: 2005
The Insects: An Outline of Entomology (3rd edition), P. Gullan and P. Cranston: book review
- Authors: Villet, Martin H
- Date: 2005
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/451777 , vital:75076 , https://hdl.handle.net/10520/EJC32612
- Description: The field of entomology is constantly developing, often at a rap-id pace, which means that publications date fairly quickly. A review in Nature of the first edition of this textbook stated, 'Students wanting a single book to give them the whole picture need look no further'.
- Full Text:
- Date Issued: 2005
- Authors: Villet, Martin H
- Date: 2005
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/451777 , vital:75076 , https://hdl.handle.net/10520/EJC32612
- Description: The field of entomology is constantly developing, often at a rap-id pace, which means that publications date fairly quickly. A review in Nature of the first edition of this textbook stated, 'Students wanting a single book to give them the whole picture need look no further'.
- Full Text:
- Date Issued: 2005
A fuzzy classification technique for predicting species' distributions: applications using invasive alien plants and indigenous insects
- Robertson, Mark P, Villet, Martin H, Palmer, Anthony R
- Authors: Robertson, Mark P , Villet, Martin H , Palmer, Anthony R
- Date: 2004
- Language: English
- Type: text , Article
- Identifier: vital:6897 , http://hdl.handle.net/10962/d1011659 , http://dx.doi.org/10.1111/j.1366-9516.2004.00108.x
- Description: A new predictive modelling technique called the fuzzy envelope model (FEM) is introduced. The technique can be used to predict potential distributions of organisms using presence-only locality records and a set of environmental predictor variables. FEM uses fuzzy logic to classify a set of predictor variable maps based on the values associated with presence records and combines the results to produce a potential distribution map for a target species. This technique represents several refinements of the envelope approach used in the BIOCLIM modelling package. These refinements are related to the way in which FEMs deal with uncertainty, the way in which this uncertainty is represented in the resultant potential distribution maps, and the way that these maps can be interpreted and applied. To illustrate its potential use in biogeographical studies, FEM was applied to predicting the potential distribution of three invasive alien plant species (Lantana camara L., Ricinus communis L. and Solanum mauritianum Scop.), and three native cicada species (Capicada decora Germar, Platypleura deusta Thun. and P. capensis L.) in South Africa, Lesotho and Swaziland. These models were quantitatively compared with models produced by means of the algorithm used in the BIOCLIM modelling package, which is referred to as a crisp envelope model (the CEM design). The average performance of models of the FEM design was consistently higher than those of the CEM design. There were significant differences in model performance among species but there was no significant interaction between model design and species. The average maximum kappa value ranged from 0.70 to 0.90 for FEM design and from 0.57 to 0.89 for the CEM design, which can be described as 'good' to 'excellent' using published ranges of agreement for the kappa statistic. This technique can be used to predict species' potential distributions that could be used for identifying regions at risk from invasion by alien species. These predictions could also be used in conservation planning in the case of native species.
- Full Text:
- Date Issued: 2004
- Authors: Robertson, Mark P , Villet, Martin H , Palmer, Anthony R
- Date: 2004
- Language: English
- Type: text , Article
- Identifier: vital:6897 , http://hdl.handle.net/10962/d1011659 , http://dx.doi.org/10.1111/j.1366-9516.2004.00108.x
- Description: A new predictive modelling technique called the fuzzy envelope model (FEM) is introduced. The technique can be used to predict potential distributions of organisms using presence-only locality records and a set of environmental predictor variables. FEM uses fuzzy logic to classify a set of predictor variable maps based on the values associated with presence records and combines the results to produce a potential distribution map for a target species. This technique represents several refinements of the envelope approach used in the BIOCLIM modelling package. These refinements are related to the way in which FEMs deal with uncertainty, the way in which this uncertainty is represented in the resultant potential distribution maps, and the way that these maps can be interpreted and applied. To illustrate its potential use in biogeographical studies, FEM was applied to predicting the potential distribution of three invasive alien plant species (Lantana camara L., Ricinus communis L. and Solanum mauritianum Scop.), and three native cicada species (Capicada decora Germar, Platypleura deusta Thun. and P. capensis L.) in South Africa, Lesotho and Swaziland. These models were quantitatively compared with models produced by means of the algorithm used in the BIOCLIM modelling package, which is referred to as a crisp envelope model (the CEM design). The average performance of models of the FEM design was consistently higher than those of the CEM design. There were significant differences in model performance among species but there was no significant interaction between model design and species. The average maximum kappa value ranged from 0.70 to 0.90 for FEM design and from 0.57 to 0.89 for the CEM design, which can be described as 'good' to 'excellent' using published ranges of agreement for the kappa statistic. This technique can be used to predict species' potential distributions that could be used for identifying regions at risk from invasion by alien species. These predictions could also be used in conservation planning in the case of native species.
- Full Text:
- Date Issued: 2004
Endothermy in African Platypleurine Cicadas: the influence of body size and habitat (Hemiptera: Cicadidae)
- Sanborn, Allen F, Villet, Martin H, Phillips, Polly K F
- Authors: Sanborn, Allen F , Villet, Martin H , Phillips, Polly K F
- Date: 2004
- Language: English
- Type: text , Article
- Identifier: vital:6925 , http://hdl.handle.net/10962/d1011912
- Description: The platypleurine cicadas have a wide distribution across Africa and southern Asia. We investigate endothermy as a thermoregulatory strategy in 11 South African species from five genera, with comparisons to the lone ectothermic platypleurine we found, in an attempt to ascertain any influence that habitat and/or body size have on the expression of endothermy in the platypleurine cicadas. Field measurements of body temperature (Tb) show that these animals regulate Tb through endogenous heat production. Heat production in the laboratory elevated Tb to the same range as in animals active in the field. Maximum Tb measured during calling activity when there was no access to solar radiation ranged from 13.2° to 22.3°C above ambient temperature in the five species measured. The mean Tb during activity without access to solar radiation did not differ from the mean Tb during diurnal activity. All platypleurines exhibit a unique behavior for cicadas while warming endogenously, a temperature- dependent telescoping pulsation of the abdomen that probably functions in ventilation. Platypleurines generally call from trunks and branches within the canopy and appear to rely on endothermy even when the sun is available to elevate Tb, in contrast to the facultative endothermy exhibited by New World endothermic species. The two exceptions to this generalization we found within the platypleurines are Platypleura wahlbergi and Albanycada albigera, which were the smallest species studied. The small size of P. wahlbergi appears to have altered their thermoregulatory strategy to one of facultative endothermy, whereby they use the sun when it is available to facilitate increases in Tb. Albanycada albigera is the only ectothermic platypleurine we found. The habitat and host plant association of A. albigera appear to have influenced the choice of ectothermy as a thermoregulatory strategy, as the species possesses the metabolic machinery to elevate to the Tb range observed in the endothermic species. Therefore, size and habitat appear to influence the expression of thermoregulatory strategies in African platypleurine cicadas.
- Full Text:
- Date Issued: 2004
- Authors: Sanborn, Allen F , Villet, Martin H , Phillips, Polly K F
- Date: 2004
- Language: English
- Type: text , Article
- Identifier: vital:6925 , http://hdl.handle.net/10962/d1011912
- Description: The platypleurine cicadas have a wide distribution across Africa and southern Asia. We investigate endothermy as a thermoregulatory strategy in 11 South African species from five genera, with comparisons to the lone ectothermic platypleurine we found, in an attempt to ascertain any influence that habitat and/or body size have on the expression of endothermy in the platypleurine cicadas. Field measurements of body temperature (Tb) show that these animals regulate Tb through endogenous heat production. Heat production in the laboratory elevated Tb to the same range as in animals active in the field. Maximum Tb measured during calling activity when there was no access to solar radiation ranged from 13.2° to 22.3°C above ambient temperature in the five species measured. The mean Tb during activity without access to solar radiation did not differ from the mean Tb during diurnal activity. All platypleurines exhibit a unique behavior for cicadas while warming endogenously, a temperature- dependent telescoping pulsation of the abdomen that probably functions in ventilation. Platypleurines generally call from trunks and branches within the canopy and appear to rely on endothermy even when the sun is available to elevate Tb, in contrast to the facultative endothermy exhibited by New World endothermic species. The two exceptions to this generalization we found within the platypleurines are Platypleura wahlbergi and Albanycada albigera, which were the smallest species studied. The small size of P. wahlbergi appears to have altered their thermoregulatory strategy to one of facultative endothermy, whereby they use the sun when it is available to facilitate increases in Tb. Albanycada albigera is the only ectothermic platypleurine we found. The habitat and host plant association of A. albigera appear to have influenced the choice of ectothermy as a thermoregulatory strategy, as the species possesses the metabolic machinery to elevate to the Tb range observed in the endothermic species. Therefore, size and habitat appear to influence the expression of thermoregulatory strategies in African platypleurine cicadas.
- Full Text:
- Date Issued: 2004
Mechanisms generating biological diversity in the genus Platypleura Amyot & Serville, 1843 (Hemiptera: Cicadidae) in southern Africa: implications of a preliminary molecular phylogeny
- Villet, Martin H, Barker, Nigel P, Lunt, Nicola
- Authors: Villet, Martin H , Barker, Nigel P , Lunt, Nicola
- Date: 2004
- Language: English
- Type: Article
- Identifier: vital:6554 , http://hdl.handle.net/10962/d1006012
- Description: Truly understanding biological diversity requires a move from descriptive studies to mechanistic interpretations based on comparative biology and a thorough recognition of the natural history of the focal organisms. A useful step in such comparative studies is the generation of a phylogeny, so that one can assess the phylogenetic independence of the focal taxa and trace the evolutionary significance of their characteristics. As a preliminary to such studies on the platypleurine cicada genus Platypleura, we sequenced 498 bases of the cytochrome oxidase I (COI) gene from thirteen African species. To circumvent problems with outgroup selection, we also included sequences from representatives of the platypleurine genera Brevisiana, Capcicada, Munza, Oxypleura, Severiana, and Systophlochius, all of the subtribe Platypleuriti, and two species of the genus Ugada, of the subtribe Hainanosemiiti. The resulting phylogenies support the synonymization of the monotypic genus Systophlochius with the widespread, speciose genus Platypleura; confirm the placement of Platypleura sp. 7 in that genus; and confirm the independence of Capcicada and Platypleura. Although the preliminary phylogeny lacks strong support at many nodes, it suggests that three radiations of Platypleura have occurred in southern Africa and that there was progressive southward speciation of these radiations. A novel modification of the ancestral area analysis further suggests that the group has an ancestral association with acacias but there were five independent speciation events associated with host- switching. These insights can be summarized by a general hypothesis that the mechanisms underlying platypleurine biodiversity in southern Africa involve two ancient vicariance events and subsequent speciation by vicariance, switching of plant associations, and changes of habitat preferences. We offer this example to illustrate how analysis of preliminary data can help to generate hypotheticodeductive research hypotheses, to provoke interest in testing these hypotheses, and to illustrate the utility of phylogenies beyond systematics.
- Full Text:
- Date Issued: 2004
- Authors: Villet, Martin H , Barker, Nigel P , Lunt, Nicola
- Date: 2004
- Language: English
- Type: Article
- Identifier: vital:6554 , http://hdl.handle.net/10962/d1006012
- Description: Truly understanding biological diversity requires a move from descriptive studies to mechanistic interpretations based on comparative biology and a thorough recognition of the natural history of the focal organisms. A useful step in such comparative studies is the generation of a phylogeny, so that one can assess the phylogenetic independence of the focal taxa and trace the evolutionary significance of their characteristics. As a preliminary to such studies on the platypleurine cicada genus Platypleura, we sequenced 498 bases of the cytochrome oxidase I (COI) gene from thirteen African species. To circumvent problems with outgroup selection, we also included sequences from representatives of the platypleurine genera Brevisiana, Capcicada, Munza, Oxypleura, Severiana, and Systophlochius, all of the subtribe Platypleuriti, and two species of the genus Ugada, of the subtribe Hainanosemiiti. The resulting phylogenies support the synonymization of the monotypic genus Systophlochius with the widespread, speciose genus Platypleura; confirm the placement of Platypleura sp. 7 in that genus; and confirm the independence of Capcicada and Platypleura. Although the preliminary phylogeny lacks strong support at many nodes, it suggests that three radiations of Platypleura have occurred in southern Africa and that there was progressive southward speciation of these radiations. A novel modification of the ancestral area analysis further suggests that the group has an ancestral association with acacias but there were five independent speciation events associated with host- switching. These insights can be summarized by a general hypothesis that the mechanisms underlying platypleurine biodiversity in southern Africa involve two ancient vicariance events and subsequent speciation by vicariance, switching of plant associations, and changes of habitat preferences. We offer this example to illustrate how analysis of preliminary data can help to generate hypotheticodeductive research hypotheses, to provoke interest in testing these hypotheses, and to illustrate the utility of phylogenies beyond systematics.
- Full Text:
- Date Issued: 2004
Parasitoids associated with the diamondback moth, Plutella xylostella (L.), in the Eastern Cape, South Africa
- Smith, Tamara J, Villet, Martin H
- Authors: Smith, Tamara J , Villet, Martin H
- Date: 2004
- Subjects: To be catalogued
- Language: English
- Type: text , conference
- Identifier: http://hdl.handle.net/10962/442795 , vital:74034 , ISBN , https://www.cabidigitallibrary.org/doi/full/10.5555/20093098381
- Description: Seasonal fluctuations of diamondback moth and its hymenopteran parasitoids were recorded weekly from April 1997 to November 1999 at four cabbage sites in the Grahamstown area of the Eastern Cape, South Africa. Two sites were commercial farms with active spraying programmes; the others were unsprayed. Infestation levels were highest during spring (September to November) and autumn (March to May), where 100% infestation of plants was reached at times. The highest infestation was found during the spring months, where 12 larvae/plant were found at the unsprayed sites and between 6 and 10 larvae at the sprayed sites. At the unsprayed sites abundance of diamondback moth larvae and parasitoids was high during 1997, but much lower during 1998 and 1999, indicating possible control by the parasitoids. Nine species of parasitoid were recorded from diamondback moth during this period and four (Cotesia plutellae (Kurdjumov) (Hymenoptera: Braconidae), Diadegma mollipla (Holmgren) (Hymenoptera: Ichneumonidae), Diadromus collaris Gravenhorst (Hymenoptera: Ichneumonidae) and Oomyzus sokolowskii (Kurdjumov) (Hymenoptera: Eulophidae)) showed potential as biological control agents. The highest rate of parasitism was found from mid-autumn to the beginning of winter (April to June) and from mid-spring to the beginning of summer (October to December). Percent parasitism varied throughout the year, ranging between 10% and 80%. Parasitism of 100% was observed when moth numbers were low. Different species of parasitoids were found to be dominant at different times of the year.
- Full Text:
- Date Issued: 2004
- Authors: Smith, Tamara J , Villet, Martin H
- Date: 2004
- Subjects: To be catalogued
- Language: English
- Type: text , conference
- Identifier: http://hdl.handle.net/10962/442795 , vital:74034 , ISBN , https://www.cabidigitallibrary.org/doi/full/10.5555/20093098381
- Description: Seasonal fluctuations of diamondback moth and its hymenopteran parasitoids were recorded weekly from April 1997 to November 1999 at four cabbage sites in the Grahamstown area of the Eastern Cape, South Africa. Two sites were commercial farms with active spraying programmes; the others were unsprayed. Infestation levels were highest during spring (September to November) and autumn (March to May), where 100% infestation of plants was reached at times. The highest infestation was found during the spring months, where 12 larvae/plant were found at the unsprayed sites and between 6 and 10 larvae at the sprayed sites. At the unsprayed sites abundance of diamondback moth larvae and parasitoids was high during 1997, but much lower during 1998 and 1999, indicating possible control by the parasitoids. Nine species of parasitoid were recorded from diamondback moth during this period and four (Cotesia plutellae (Kurdjumov) (Hymenoptera: Braconidae), Diadegma mollipla (Holmgren) (Hymenoptera: Ichneumonidae), Diadromus collaris Gravenhorst (Hymenoptera: Ichneumonidae) and Oomyzus sokolowskii (Kurdjumov) (Hymenoptera: Eulophidae)) showed potential as biological control agents. The highest rate of parasitism was found from mid-autumn to the beginning of winter (April to June) and from mid-spring to the beginning of summer (October to December). Percent parasitism varied throughout the year, ranging between 10% and 80%. Parasitism of 100% was observed when moth numbers were low. Different species of parasitoids were found to be dominant at different times of the year.
- Full Text:
- Date Issued: 2004
Recent African derivation of Chrysomya putoria from C. chloropyga and mitochondrial DNA paraphyly of cytochrome oxidase subunit one in blowflies of forensic importance
- Wells, J D, Lunt, Nicola, Villet, Martin H
- Authors: Wells, J D , Lunt, Nicola , Villet, Martin H
- Date: 2004
- Language: English
- Type: text , Article
- Identifier: vital:6888 , http://hdl.handle.net/10962/d1011648
- Description: Chrysomya chloropyga (Wiedemann) and C. putoria (Wiedemann) (Diptera: Calliphoridae) are closely related Afrotropical blowflies that breed in carrion and latrines, reaching high density in association with humans and spreading to other continents. In some cases of human death, Chyrsomya specimens provide forensic clues. Because the immature stages of such flies are often difficult to identify taxonomically, it is useful to develop DNA-based tests for specimen identification. Therefore we attempted to distinguish between C. chloropyga and C. putoria using mitochondrial DNA (mtDNA) sequence data from a 593-bp region of the gene for cytochrome oxidase subunit one (COI). Twelve specimens from each species yielded a total of five haplotypes, none being unique to C. putoria. Therefore it was not possible to distinguish between the two species using this locus. Maximum parsimony analysis indicated paraphyletic C. chloropyga mtDNA with C. putoria nested therein. Based on these and previously published data, we infer that C. putoria diverged very recently from C. chloropyga.
- Full Text:
- Date Issued: 2004
- Authors: Wells, J D , Lunt, Nicola , Villet, Martin H
- Date: 2004
- Language: English
- Type: text , Article
- Identifier: vital:6888 , http://hdl.handle.net/10962/d1011648
- Description: Chrysomya chloropyga (Wiedemann) and C. putoria (Wiedemann) (Diptera: Calliphoridae) are closely related Afrotropical blowflies that breed in carrion and latrines, reaching high density in association with humans and spreading to other continents. In some cases of human death, Chyrsomya specimens provide forensic clues. Because the immature stages of such flies are often difficult to identify taxonomically, it is useful to develop DNA-based tests for specimen identification. Therefore we attempted to distinguish between C. chloropyga and C. putoria using mitochondrial DNA (mtDNA) sequence data from a 593-bp region of the gene for cytochrome oxidase subunit one (COI). Twelve specimens from each species yielded a total of five haplotypes, none being unique to C. putoria. Therefore it was not possible to distinguish between the two species using this locus. Maximum parsimony analysis indicated paraphyletic C. chloropyga mtDNA with C. putoria nested therein. Based on these and previously published data, we infer that C. putoria diverged very recently from C. chloropyga.
- Full Text:
- Date Issued: 2004
Seasonal rates of parasitism of diamondback moth (Plutella xylostella) in subsistence cabbage crops in the Eastern Cape, South Africa
- Mkize, Nolwazi, Villet, Martin H
- Authors: Mkize, Nolwazi , Villet, Martin H
- Date: 2004
- Subjects: To be catalogued
- Language: English
- Type: text , book chapter
- Identifier: http://hdl.handle.net/10962/442807 , vital:74035 , ISBN , https://www.torrossa.com/en/resources/an/5063829#page=221
- Description: Smith's (personal communication) work in a continuous, commercial cabbage-growing area near Grahamstown showed that parasitism of diamondback moth averaged over 60% and could reach 100%. In many parts of the world cabbage crops are not under continuous cultivation, and periodic cropping Systems may demonstrate différent patterns of parasitism, especially in disrupted, patchy subsistence crops. Cabbage (Brassica oleracea) is the most commonly grown cruciferous crop in subsistence gardens in the suburbs of Grahamstown East. The subsistence farmers' crops are considered patchy because the cabbages are grown in small and relatively widely separated plots. Thèse gardens provided an opportunity to follow Talekar and Shelton's (1993) suggestion to investigate the population dynamics of P. xylostella (a useful model pest) and its rate of parasitism on cabbages of subsistence farmers where commercial pesticides are used less.
- Full Text:
- Date Issued: 2004
- Authors: Mkize, Nolwazi , Villet, Martin H
- Date: 2004
- Subjects: To be catalogued
- Language: English
- Type: text , book chapter
- Identifier: http://hdl.handle.net/10962/442807 , vital:74035 , ISBN , https://www.torrossa.com/en/resources/an/5063829#page=221
- Description: Smith's (personal communication) work in a continuous, commercial cabbage-growing area near Grahamstown showed that parasitism of diamondback moth averaged over 60% and could reach 100%. In many parts of the world cabbage crops are not under continuous cultivation, and periodic cropping Systems may demonstrate différent patterns of parasitism, especially in disrupted, patchy subsistence crops. Cabbage (Brassica oleracea) is the most commonly grown cruciferous crop in subsistence gardens in the suburbs of Grahamstown East. The subsistence farmers' crops are considered patchy because the cabbages are grown in small and relatively widely separated plots. Thèse gardens provided an opportunity to follow Talekar and Shelton's (1993) suggestion to investigate the population dynamics of P. xylostella (a useful model pest) and its rate of parasitism on cabbages of subsistence farmers where commercial pesticides are used less.
- Full Text:
- Date Issued: 2004
Similarities and differences between rivers of the Kruger National Park
- Muller, Nikite W J, Villet, Martin H
- Authors: Muller, Nikite W J , Villet, Martin H
- Date: 2004
- Language: English
- Type: text
- Identifier: vital:537 , http://hdl.handle.net/10962/d1009527
- Description: [From Introduction] Aquatic ecosystems play an important role in the maintenance of ecological diversity and ecosystem functioning at both local and regional scales (Roux et al, 1999). Effective management of riverine ecosystems requires an understanding of their ecosystem processes, hi order to understand ecosystem processes, and interactions between the landscape and riverine ecosystems, it is necessary to have both spatial and temporal data at both landscape and site-specific scales (Allan and Johnson, 1997). There are many tools available for the analysis of these data to provide insight and understanding of the data in order to understand influences on aquatic ecosystems. Increasingly complex computational tools allow analysis and modeling of data in order to explain river, and subsequent biological, processes from landscape (catchment) processes (Johnson and Gage, 1997), although the scale at which analysis and interpretation occurs is important. Science and management need to interact in order to truly succeed in effectively applying adaptive management and incorporate monitoring and assessment programmes in management processes (Rogers and Biggs, 1999). However, water resource management is often undertaken in the context of incomplete information and knowledge of functioning ecosystem processess and responses: this inevitably leads to uncertainty and unpredictability (Roux et al. 1999). One of the major challenges for managing rivers is to be able to monitor rivers effectively in order to detect changes as they occur, to identify the causes of the changes and to distinguish between natural and anthropogenic causes of change. Adaptive management is required to effectively manage rivers, but this does require that there is an understanding of, and information for, the rivers being managed. Rogers and Biggs (1999) highlighted the need to integrate monitoring programmes with indicators in order to undertake assessments of ecosystem health as part of the management plan of the rivers of the Kruger National Park in order to maintain, and restore, natural river ecosystem health and biodiversity (Rogers and Bestbier, 1997). One of the main aims of the Kruger National Park Rivers Research Programme (KNPRRP) was to contribute to the conservation of the natural environment by developing skills and methods to understand the ecological functioning of the natural environment and to predict responses of the river systems to natural and anthropogenic changes in order to effectively manage them (Breen, 1994, in van Rensburg and Dent, 1997). Classification systems are able to provide useful management information, but many have focussed on abiotic rather than biotic factors because resultant biotic patterns are likely to be correlated with abiotic components (Solomon et al., 1999). Much of the classification of the Kruger National Park has focussed on classification of land with little regard for rivers (these were incorporated into the two classification systems proposed by Venter and Gertenbach (in Solomon et al., 1999)). The objective of this project is to identify similarities and differences between the five major rivers of the Kruger National Park, towards the design and testing of a classification framework in order to aid management of the KNP rivers by contributing to effective monitoring. This will be achieved through the following: 1. collate available (current and historical) information concerning physical and biological variables for the Luvuvhu, Letaba, Olifants, Sabie and Crocodile Rivers, using a common dataset to establish the degree of similarities and differences between these five major rivers of the KNP; and 2. determine how different the rivers are, in order to optimize monitoring and management programmes for these differences. The aim of this project was not to classify the rivers of the KNP. The project rather aims to identify gaps in data availability which may result in inadequate and inappropriate management of the rivers. Results (in the form of a data matrix) emanating from this study could assist in establishing expected natural conditions and biota in the five major rivers of the KNP, and knowledge from data-rich rivers (e.g. Sabie River) could potentially be extrapolated to data-poor rivers, or sections of rivers. Invertebrates and fish are the main tools of aquatic species biodiversity monitoring, and require an understanding of the natural presence, absence and abundance patterns in aquatic ecosystems. This study contributes to this understanding by organising available information of biotic and abiotic information.
- Full Text:
- Date Issued: 2004
- Authors: Muller, Nikite W J , Villet, Martin H
- Date: 2004
- Language: English
- Type: text
- Identifier: vital:537 , http://hdl.handle.net/10962/d1009527
- Description: [From Introduction] Aquatic ecosystems play an important role in the maintenance of ecological diversity and ecosystem functioning at both local and regional scales (Roux et al, 1999). Effective management of riverine ecosystems requires an understanding of their ecosystem processes, hi order to understand ecosystem processes, and interactions between the landscape and riverine ecosystems, it is necessary to have both spatial and temporal data at both landscape and site-specific scales (Allan and Johnson, 1997). There are many tools available for the analysis of these data to provide insight and understanding of the data in order to understand influences on aquatic ecosystems. Increasingly complex computational tools allow analysis and modeling of data in order to explain river, and subsequent biological, processes from landscape (catchment) processes (Johnson and Gage, 1997), although the scale at which analysis and interpretation occurs is important. Science and management need to interact in order to truly succeed in effectively applying adaptive management and incorporate monitoring and assessment programmes in management processes (Rogers and Biggs, 1999). However, water resource management is often undertaken in the context of incomplete information and knowledge of functioning ecosystem processess and responses: this inevitably leads to uncertainty and unpredictability (Roux et al. 1999). One of the major challenges for managing rivers is to be able to monitor rivers effectively in order to detect changes as they occur, to identify the causes of the changes and to distinguish between natural and anthropogenic causes of change. Adaptive management is required to effectively manage rivers, but this does require that there is an understanding of, and information for, the rivers being managed. Rogers and Biggs (1999) highlighted the need to integrate monitoring programmes with indicators in order to undertake assessments of ecosystem health as part of the management plan of the rivers of the Kruger National Park in order to maintain, and restore, natural river ecosystem health and biodiversity (Rogers and Bestbier, 1997). One of the main aims of the Kruger National Park Rivers Research Programme (KNPRRP) was to contribute to the conservation of the natural environment by developing skills and methods to understand the ecological functioning of the natural environment and to predict responses of the river systems to natural and anthropogenic changes in order to effectively manage them (Breen, 1994, in van Rensburg and Dent, 1997). Classification systems are able to provide useful management information, but many have focussed on abiotic rather than biotic factors because resultant biotic patterns are likely to be correlated with abiotic components (Solomon et al., 1999). Much of the classification of the Kruger National Park has focussed on classification of land with little regard for rivers (these were incorporated into the two classification systems proposed by Venter and Gertenbach (in Solomon et al., 1999)). The objective of this project is to identify similarities and differences between the five major rivers of the Kruger National Park, towards the design and testing of a classification framework in order to aid management of the KNP rivers by contributing to effective monitoring. This will be achieved through the following: 1. collate available (current and historical) information concerning physical and biological variables for the Luvuvhu, Letaba, Olifants, Sabie and Crocodile Rivers, using a common dataset to establish the degree of similarities and differences between these five major rivers of the KNP; and 2. determine how different the rivers are, in order to optimize monitoring and management programmes for these differences. The aim of this project was not to classify the rivers of the KNP. The project rather aims to identify gaps in data availability which may result in inadequate and inappropriate management of the rivers. Results (in the form of a data matrix) emanating from this study could assist in establishing expected natural conditions and biota in the five major rivers of the KNP, and knowledge from data-rich rivers (e.g. Sabie River) could potentially be extrapolated to data-poor rivers, or sections of rivers. Invertebrates and fish are the main tools of aquatic species biodiversity monitoring, and require an understanding of the natural presence, absence and abundance patterns in aquatic ecosystems. This study contributes to this understanding by organising available information of biotic and abiotic information.
- Full Text:
- Date Issued: 2004