Contributions to our knowledge of the biology of Machiloides Delanyi Wygodzinsky and Ctenolepisma Longicaudata Escherich : (Hexapoda Thysanura)
- Authors: Heeg, J. (Jan)
- Date: 1963
- Subjects: Insects -- Adaptation , Insects -- Physiology , Thysanura , Apterygota
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5856 , http://hdl.handle.net/10962/d1012261 , Insects -- Adaptation , Insects -- Physiology , Thysanura , Apterygota
- Description: Among the South African Thysanura, the order Lepismatoidea has spread over the whole sub-continent, while all except one species of the order Machiloidea are confined to the discontinuous forest belt which lies below the escarpment of the inland plateau. The Machiloidea are not , however, strictly confined to the actual forests within their geographical region, some species invading regions of considerable aridity. Investigations on the ecology, water relations and orientation behaviour of a representative species of each order have been carried out. These have revealed that: (i) the physical conditions in the typical niche of the Machiloidea are extremely stable, whereas those in the habitat of the Lepismatoidea are subject to some considerable fluctuation. (ii) the Lepismatoidea are more resistant to desiccation than the Machiloidea; in both cases this resistance is due in part to physical barriers in the cuticle and partly to an active metabolic process. (iii) the Machiloidea rely on their eversible vesicles, situated on the abdominal coxosternites, for the uptake of water which cannot be drunk, such as a thin film of water or soil capillary water. (iv) the Lepismatoidea are able to absorb water from a subsaturated atmosphere. (v) the behavioural responses of both in respect of humidity, temperature, light and gravity, are such as to keep them in conditions within the range of their physiological limitations. From these results it is concluded that the Machiloidea can survive outside the shelter of forests, provided that water is readily available in some form in which it can be absorbed by the animals. The general implications of the results are such as to permit the erection of an hypothesis explaining the distribution of the Thysanura in South Africa in terms of t he availability of wate. The results also lead to speculations on the evolution of the Pterygota.
- Full Text:
- Date Issued: 1963
- Authors: Heeg, J. (Jan)
- Date: 1963
- Subjects: Insects -- Adaptation , Insects -- Physiology , Thysanura , Apterygota
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5856 , http://hdl.handle.net/10962/d1012261 , Insects -- Adaptation , Insects -- Physiology , Thysanura , Apterygota
- Description: Among the South African Thysanura, the order Lepismatoidea has spread over the whole sub-continent, while all except one species of the order Machiloidea are confined to the discontinuous forest belt which lies below the escarpment of the inland plateau. The Machiloidea are not , however, strictly confined to the actual forests within their geographical region, some species invading regions of considerable aridity. Investigations on the ecology, water relations and orientation behaviour of a representative species of each order have been carried out. These have revealed that: (i) the physical conditions in the typical niche of the Machiloidea are extremely stable, whereas those in the habitat of the Lepismatoidea are subject to some considerable fluctuation. (ii) the Lepismatoidea are more resistant to desiccation than the Machiloidea; in both cases this resistance is due in part to physical barriers in the cuticle and partly to an active metabolic process. (iii) the Machiloidea rely on their eversible vesicles, situated on the abdominal coxosternites, for the uptake of water which cannot be drunk, such as a thin film of water or soil capillary water. (iv) the Lepismatoidea are able to absorb water from a subsaturated atmosphere. (v) the behavioural responses of both in respect of humidity, temperature, light and gravity, are such as to keep them in conditions within the range of their physiological limitations. From these results it is concluded that the Machiloidea can survive outside the shelter of forests, provided that water is readily available in some form in which it can be absorbed by the animals. The general implications of the results are such as to permit the erection of an hypothesis explaining the distribution of the Thysanura in South Africa in terms of t he availability of wate. The results also lead to speculations on the evolution of the Pterygota.
- Full Text:
- Date Issued: 1963
Studies on certain aspects of the neuromuscular physiology of insects
- Authors: Moran, V. C. (V. Cliff)
- Date: 1963
- Subjects: Insects -- Physiology
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5866 , http://hdl.handle.net/10962/d1012879
- Description: It is well known that high potassium ion concentrations depolarize nervous tissue and it has been suggested that the nerve sheath surrounding the peripheral nerves of insects serves as a protective barrier for the exclusion of potassium ions, in the haemolymph, from the immediate environment of axons. Further it is known that the concentration of potassium ions in the haemolymph of phytophagous insects is far higher than that in predatory forms; this has led to the suggestion that the nerve sheath in plant feeding insects should be more highly developed than that of entomophagous insects. In this work the structure of the nerve sheath in phytophagous and predatory insects has been studied and this assumption has been shown to be groundles. However, preliminary experiments on the effects of ions and drugs on the peripheral nerves of phytophagous and predatory insects have shown that there is a definite difference in susceptibility between the nerves of these two forms and this has led to the postulate of a diffusion barrier beneath the level of the nerve sheath, which is more highly developed in phytophagous than in predatory forms. The properties of this second barrier are discussed. Part 1. , During the course of the work which has been described in Part 1- an outbreak of large saturniid moths Nudaurelia cytherea capensis Stoll.) occurred in the Grahamstown area. It was felt that an investigation into the properties of the flight motor of this moth, which has an extremely low wing beat frquency, might be rewarding as our knowledge of the flight motor in insects is limited to those with very much higher wing beat frequencies than that of this moth. The anatomy, innervation and histology of the flight muscles of Nudaurelia are described and it is shown that the flight motor of this moth is functionally different to that of other insects which have been investigated. Further, Nudaurelia shows a characteristic warm-up fluttering of the wings prior to flight - this phenomenon has also been examined in the following investigation. This study has yielded information about the location of a warm-up centre in the central nervous system of this moth. Part 2.
- Full Text:
- Date Issued: 1963
- Authors: Moran, V. C. (V. Cliff)
- Date: 1963
- Subjects: Insects -- Physiology
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5866 , http://hdl.handle.net/10962/d1012879
- Description: It is well known that high potassium ion concentrations depolarize nervous tissue and it has been suggested that the nerve sheath surrounding the peripheral nerves of insects serves as a protective barrier for the exclusion of potassium ions, in the haemolymph, from the immediate environment of axons. Further it is known that the concentration of potassium ions in the haemolymph of phytophagous insects is far higher than that in predatory forms; this has led to the suggestion that the nerve sheath in plant feeding insects should be more highly developed than that of entomophagous insects. In this work the structure of the nerve sheath in phytophagous and predatory insects has been studied and this assumption has been shown to be groundles. However, preliminary experiments on the effects of ions and drugs on the peripheral nerves of phytophagous and predatory insects have shown that there is a definite difference in susceptibility between the nerves of these two forms and this has led to the postulate of a diffusion barrier beneath the level of the nerve sheath, which is more highly developed in phytophagous than in predatory forms. The properties of this second barrier are discussed. Part 1. , During the course of the work which has been described in Part 1- an outbreak of large saturniid moths Nudaurelia cytherea capensis Stoll.) occurred in the Grahamstown area. It was felt that an investigation into the properties of the flight motor of this moth, which has an extremely low wing beat frquency, might be rewarding as our knowledge of the flight motor in insects is limited to those with very much higher wing beat frequencies than that of this moth. The anatomy, innervation and histology of the flight muscles of Nudaurelia are described and it is shown that the flight motor of this moth is functionally different to that of other insects which have been investigated. Further, Nudaurelia shows a characteristic warm-up fluttering of the wings prior to flight - this phenomenon has also been examined in the following investigation. This study has yielded information about the location of a warm-up centre in the central nervous system of this moth. Part 2.
- Full Text:
- Date Issued: 1963
Studies on the behaviour of unfed blue tick larvae (Boophilus decoloratus)
- Authors: Goldsmid, John Marsden
- Date: 1963
- Subjects: Boophilus -- South Africa , Ticks -- Behavior -- South Africa , Ticks -- Physiology -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5852 , http://hdl.handle.net/10962/d1012044 , Boophilus -- South Africa , Ticks -- Behavior -- South Africa , Ticks -- Physiology -- South Africa
- Description: Ticks "are not merely annoying pests but surpass all other anthropods in the number and variety of disease agents for which they are carriers (Chandler 1955). This statement is certainly true of Boophilus decoloratus (Koch), the blue tick, which is probably one of the most important ticks in South Africa. Various studies have been made on the blue tick in Africa, among which are investigations on taxonomy (Hoogstraal 1956); distribution (Theiler 1949 and 1962); ecology (Kraft 1961); disease transmission (Neitz and du Toit 1938; du Toit 1947; Neitz 1956 a and b); control and resistance to insecticides (du Toit, Graf and Bekker 1941; Whitnall and Bradford 1947; Whitehead 1958 and 1959) To date, the behaviour of Boophilus decoloratus has not been studied to any extent. The aim of the present work is to analyse the behaviour of the unfed larvae into its constituent patterns in order to determine what are the significant environmental factors which affect this behaviour. It is also hoped that the present laboratory studies might help in understanding their behaviour in the field. Intro., p. 1.
- Full Text:
- Date Issued: 1963
- Authors: Goldsmid, John Marsden
- Date: 1963
- Subjects: Boophilus -- South Africa , Ticks -- Behavior -- South Africa , Ticks -- Physiology -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5852 , http://hdl.handle.net/10962/d1012044 , Boophilus -- South Africa , Ticks -- Behavior -- South Africa , Ticks -- Physiology -- South Africa
- Description: Ticks "are not merely annoying pests but surpass all other anthropods in the number and variety of disease agents for which they are carriers (Chandler 1955). This statement is certainly true of Boophilus decoloratus (Koch), the blue tick, which is probably one of the most important ticks in South Africa. Various studies have been made on the blue tick in Africa, among which are investigations on taxonomy (Hoogstraal 1956); distribution (Theiler 1949 and 1962); ecology (Kraft 1961); disease transmission (Neitz and du Toit 1938; du Toit 1947; Neitz 1956 a and b); control and resistance to insecticides (du Toit, Graf and Bekker 1941; Whitnall and Bradford 1947; Whitehead 1958 and 1959) To date, the behaviour of Boophilus decoloratus has not been studied to any extent. The aim of the present work is to analyse the behaviour of the unfed larvae into its constituent patterns in order to determine what are the significant environmental factors which affect this behaviour. It is also hoped that the present laboratory studies might help in understanding their behaviour in the field. Intro., p. 1.
- Full Text:
- Date Issued: 1963
The influence of temperature in the ecology of the intermediate host snails of Schistosoma and Fasciola (Trematoda) in southern Rhodesia
- Authors: Shiff, Clive Julian
- Date: 1963
- Subjects: Schistosoma , Schistosomiasis , Fasciola , Snails -- Zimbabwe , Trematoda
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5881 , http://hdl.handle.net/10962/d1013208
- Description: The influence of temperature on the bionomics of Bulinus (Physopsis) globosus, Biomphalaria pfeifferi and Lymnaea natalensis has been studied both in the laboratory under controlled conditions and in the field under normal seasonal influences. Field studies were carried out in two different localities, one a semi-permanent pond and the other a temporary waterbody. For this purpose a sampling implement was developed. The results show the seasonal progression of these populations both with respect to estimated numbers and the size distribution of the snails. The rate of actual increase at different seasons was calculated for the three species where the data were sufficient. In the laboratory the snails were maintained at various temperatures, other conditions being kept standard. Daily records of mortality and fecundity of various cohorts reared from the egg stage enabled the compilation of life tables fof the speciesand from these data were calcualted the intrinsic rate of natural increase and other parameters. Effects of crowding in aquaria were studied. From the data obtained in the laboratory it was possible to predict the distribution and population potential for each species for snail of various environmental conditions. These predictions were, in fact, confirmed by field observation.
- Full Text:
- Date Issued: 1963
- Authors: Shiff, Clive Julian
- Date: 1963
- Subjects: Schistosoma , Schistosomiasis , Fasciola , Snails -- Zimbabwe , Trematoda
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5881 , http://hdl.handle.net/10962/d1013208
- Description: The influence of temperature on the bionomics of Bulinus (Physopsis) globosus, Biomphalaria pfeifferi and Lymnaea natalensis has been studied both in the laboratory under controlled conditions and in the field under normal seasonal influences. Field studies were carried out in two different localities, one a semi-permanent pond and the other a temporary waterbody. For this purpose a sampling implement was developed. The results show the seasonal progression of these populations both with respect to estimated numbers and the size distribution of the snails. The rate of actual increase at different seasons was calculated for the three species where the data were sufficient. In the laboratory the snails were maintained at various temperatures, other conditions being kept standard. Daily records of mortality and fecundity of various cohorts reared from the egg stage enabled the compilation of life tables fof the speciesand from these data were calcualted the intrinsic rate of natural increase and other parameters. Effects of crowding in aquaria were studied. From the data obtained in the laboratory it was possible to predict the distribution and population potential for each species for snail of various environmental conditions. These predictions were, in fact, confirmed by field observation.
- Full Text:
- Date Issued: 1963
- «
- ‹
- 1
- ›
- »