Ecology and breeding biology of Lanner Falcons in the Eastern Cape Province, South Africa
- Authors: Stephenson, Alan
- Date: 2001
- Subjects: Birds -- Breeding , Birds -- South Africa -- Eastern Cape , Birds -- Ecology , Falcons -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5667 , http://hdl.handle.net/10962/d1005352 , Birds -- Breeding , Birds -- South Africa -- Eastern Cape , Birds -- Ecology , Falcons -- South Africa -- Eastern Cape
- Description: Lanner Falcons Falco biarmicus are the commonest large falcons in Africa and this study in the coastal area of the Eastern Cape Province, South Africa investigated their ecology from 1984 to 2000. Lanners have recently been categorised as near-threatened and this study was initiated to ascertain if the population was stable. Breeding success of a small population, in different habitat types, was monitored intensively from 1997 to 2000, and the factors that inhibited breeding were investigated. The earliest onset of incubation was 17 July and the latest 16 August, with 2.2 young fledged per breeding pair over the four-year period. Incubation lasted 32 days and young fledged after 42-45 days. All nest sites were on cliffs with a mean height of 114 m, a mean vertical face of 53 m; 45% of the nests were in ravens’ nests. The aspect of cliff sites also influenced breeding success. Radio tracking was used to determine home range, habitat use and hunting methods, with prey species identified. Home ranges were between 66 km² and 249 km². Preferred prey was domestic chickens, pigeons and small birds during the breeding season. Foraging ranges were smaller in intensively cultivated areas with seed crops. Data obtained from ringing returns showed that no long distance movements occurred in this region, but two juveniles dispersed 152 km and 127 km. Conservation aspects with possible threats to Lanner Falcons such as poisons, electrocutions and direct persecution are discussed with some recommendations made for future research. Evidence from this study indicates that Lanner breeding success is not limited by nest site availability, but by rainfall timing and prey availability. Lanners foraged more in open areas than areas with tall vegetation, and benefited from intensive agriculture. This population appeared to be healthy and in no danger of declining in the near future.
- Full Text:
- Date Issued: 2001
- Authors: Stephenson, Alan
- Date: 2001
- Subjects: Birds -- Breeding , Birds -- South Africa -- Eastern Cape , Birds -- Ecology , Falcons -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5667 , http://hdl.handle.net/10962/d1005352 , Birds -- Breeding , Birds -- South Africa -- Eastern Cape , Birds -- Ecology , Falcons -- South Africa -- Eastern Cape
- Description: Lanner Falcons Falco biarmicus are the commonest large falcons in Africa and this study in the coastal area of the Eastern Cape Province, South Africa investigated their ecology from 1984 to 2000. Lanners have recently been categorised as near-threatened and this study was initiated to ascertain if the population was stable. Breeding success of a small population, in different habitat types, was monitored intensively from 1997 to 2000, and the factors that inhibited breeding were investigated. The earliest onset of incubation was 17 July and the latest 16 August, with 2.2 young fledged per breeding pair over the four-year period. Incubation lasted 32 days and young fledged after 42-45 days. All nest sites were on cliffs with a mean height of 114 m, a mean vertical face of 53 m; 45% of the nests were in ravens’ nests. The aspect of cliff sites also influenced breeding success. Radio tracking was used to determine home range, habitat use and hunting methods, with prey species identified. Home ranges were between 66 km² and 249 km². Preferred prey was domestic chickens, pigeons and small birds during the breeding season. Foraging ranges were smaller in intensively cultivated areas with seed crops. Data obtained from ringing returns showed that no long distance movements occurred in this region, but two juveniles dispersed 152 km and 127 km. Conservation aspects with possible threats to Lanner Falcons such as poisons, electrocutions and direct persecution are discussed with some recommendations made for future research. Evidence from this study indicates that Lanner breeding success is not limited by nest site availability, but by rainfall timing and prey availability. Lanners foraged more in open areas than areas with tall vegetation, and benefited from intensive agriculture. This population appeared to be healthy and in no danger of declining in the near future.
- Full Text:
- Date Issued: 2001
Feeding biology of common and blue duiker
- Authors: Kigozi, Frederick
- Date: 2001
- Subjects: Duikers -- Nutrition -- South Africa -- Eastern Cape , Sylvicapra grimmia -- Nutrition -- South Africa -- Eastern Cape , Herbivores -- Nutrition , Folivores -- Nutrition , Teeth -- Abrasion
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5625 , http://hdl.handle.net/10962/d1004725 , Duikers -- Nutrition -- South Africa -- Eastern Cape , Sylvicapra grimmia -- Nutrition -- South Africa -- Eastern Cape , Herbivores -- Nutrition , Folivores -- Nutrition , Teeth -- Abrasion
- Description: The blue duiker, Philantomba monticola and common or grey duiker, Sylvicapra grimmia represent two of the three duiker genera as well as two of the three species occurring in Southern Africa. The two species have not been adequately studied in their habitats within the Eastern Cape Province of South Africa, and this thesis centres around their biology with focus on diet and dental microwear. Faecal analysis was used to study the diet of blue duiker at Salem in the Albany district, and of common duiker on two farms, one a predominantly cattle farm at Kasouga and the other a farm for cultivation of chicory at Grants valley, both in the Bathurst district. The validity of faecal analysis was reviewed, and its applicability to blue and common duiker assessed. The method was appropriate for diet analysis of both species, as the common duiker is shy and secretive and the blue duiker is a rare and protected species which does not habituate readily. Results showed that the blue duiker was mainly folivorous with a seasonally stable diet of 79 percent dicot foliage and only 17 percent fruit. Common duiker diet at both study sites comprised mostly dicot foliage, with only two monocotyledonous plant species. Twenty-seven and nineteen plant species were identified in the diets of common duiker at Kasouga and Grants valley respectively and the annual percentage occurrences of dicot foliage in the diets were about 99 percent at both study sites. The predominantly browsing common duiker, therefore offered negligible competition for food resources to the grazing cattle on Kasouga farm. Both blue and common duiker fed selectively, with approximately one third of the total number of plant species identified in their diets providing at least 50 percent of the food eaten annually. Ehretia rigida was the most important plant species in the diets of both duiker species. Chicory, Chichorium intybus provided more than one third (35.6 percent) of the winter diet and a substantial proportion (14.4 percent) of the spring diet of common duiker at Grants valley, thereby confirming earlier reports of this species feeding on chicory and other cultivated crops. The diet of common duiker at Kasouga did not vary seasonally but that of common duiker at Grants valley did vary and this was attributed to utilisation of chicory. Results from the dental microwear analyses did not show any significant differences in dental microwear between blue and common duiker, but supported and confirmed that the two were browsing species, characterised by many pits and few scratches on their dental surfaces. A high incidence of pits was found on the dental surfaces of both duiker species, and was attributed to utilisation of fruit in the diet.
- Full Text:
- Date Issued: 2001
- Authors: Kigozi, Frederick
- Date: 2001
- Subjects: Duikers -- Nutrition -- South Africa -- Eastern Cape , Sylvicapra grimmia -- Nutrition -- South Africa -- Eastern Cape , Herbivores -- Nutrition , Folivores -- Nutrition , Teeth -- Abrasion
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5625 , http://hdl.handle.net/10962/d1004725 , Duikers -- Nutrition -- South Africa -- Eastern Cape , Sylvicapra grimmia -- Nutrition -- South Africa -- Eastern Cape , Herbivores -- Nutrition , Folivores -- Nutrition , Teeth -- Abrasion
- Description: The blue duiker, Philantomba monticola and common or grey duiker, Sylvicapra grimmia represent two of the three duiker genera as well as two of the three species occurring in Southern Africa. The two species have not been adequately studied in their habitats within the Eastern Cape Province of South Africa, and this thesis centres around their biology with focus on diet and dental microwear. Faecal analysis was used to study the diet of blue duiker at Salem in the Albany district, and of common duiker on two farms, one a predominantly cattle farm at Kasouga and the other a farm for cultivation of chicory at Grants valley, both in the Bathurst district. The validity of faecal analysis was reviewed, and its applicability to blue and common duiker assessed. The method was appropriate for diet analysis of both species, as the common duiker is shy and secretive and the blue duiker is a rare and protected species which does not habituate readily. Results showed that the blue duiker was mainly folivorous with a seasonally stable diet of 79 percent dicot foliage and only 17 percent fruit. Common duiker diet at both study sites comprised mostly dicot foliage, with only two monocotyledonous plant species. Twenty-seven and nineteen plant species were identified in the diets of common duiker at Kasouga and Grants valley respectively and the annual percentage occurrences of dicot foliage in the diets were about 99 percent at both study sites. The predominantly browsing common duiker, therefore offered negligible competition for food resources to the grazing cattle on Kasouga farm. Both blue and common duiker fed selectively, with approximately one third of the total number of plant species identified in their diets providing at least 50 percent of the food eaten annually. Ehretia rigida was the most important plant species in the diets of both duiker species. Chicory, Chichorium intybus provided more than one third (35.6 percent) of the winter diet and a substantial proportion (14.4 percent) of the spring diet of common duiker at Grants valley, thereby confirming earlier reports of this species feeding on chicory and other cultivated crops. The diet of common duiker at Kasouga did not vary seasonally but that of common duiker at Grants valley did vary and this was attributed to utilisation of chicory. Results from the dental microwear analyses did not show any significant differences in dental microwear between blue and common duiker, but supported and confirmed that the two were browsing species, characterised by many pits and few scratches on their dental surfaces. A high incidence of pits was found on the dental surfaces of both duiker species, and was attributed to utilisation of fruit in the diet.
- Full Text:
- Date Issued: 2001
The ecology and physiology of the springhare (Pedetes capensis) in the Eastern Cape Province of South Africa
- Authors: Peinke, Dean Michael
- Date: 2001
- Subjects: Hares -- South Africa -- Eastern Cape Hares -- Breeding -- South Africa -- Eastern Cape Hares -- Ecology -- South Africa -- Eastern Cape Hares -- Physiology
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5670 , http://hdl.handle.net/10962/d1005355
- Description: Springhare are large, bipedal, nocturnal, herbivorous, burrowing rodents that are found in arid and semi-arid parts of southern and eastern Africa. In this thesis I examine the general ecology, biology and physiology of these animals in the Eastern Cape Province of South Africa. An investigation of their distribution and activity in the study site showed that springhare exhibit a preference for flat, open, recently disturbed habitat that is dominated by the grass Cynodon dactylon and the sedge Cyperus esculentus. These two species constitute a major proportion of their diet. The impact of spring hare on chicory and grazing is also discussed. Nightly activity generally peaks soon after dark and decreases in the 2-4 hour period before sunrise. This pattern is, however, modified by moonlight. Springhare typically respond to moonlight by reducing aboveground activity, shifting their activity to dark moonless periods of the night, and by reducing their use of open space. Contrary to earlier reports, springhare utilise several different burrow systems spread over large areas. They regularly change burrow systems and seldom spend more than a few consecutive days in each. Springhare do not appear to defend territories but recently used burrows appear to be avoided by conspecifics. Males and females on average use a similar number of burrows, scattered over similar sized areas. Burrows are shown to provide a stable microclimate of moderate temperature and high humidity throughout the year. Reproduction is continuous and there is no synchronised breeding season. The ability to reproduce throughout the year is attributed primarily to their ability to utilise subterranean food stores. The overall reproductive strategy of springhare (a single young with long gestation and weaning) is unusual for a mammal of this size but may be linked to low levels of adult and juvenile mortality. Physiologically, springhare are reasonably well adapted to life in hot, arid environments. They produce a concentrated urine, exhibit a high tolerance to dehydration, are good osmoregulators capable of maintaining plasma volume, osmolality and ion balance over long periods of water deprivation, and are able to produce dry faeces. They are also good thermoregulators at low ambient temperatures, which are usually encountered at night, but are poor thermoregulators at high ambient temperatures, which they avoid behaviourally.
- Full Text:
- Date Issued: 2001
- Authors: Peinke, Dean Michael
- Date: 2001
- Subjects: Hares -- South Africa -- Eastern Cape Hares -- Breeding -- South Africa -- Eastern Cape Hares -- Ecology -- South Africa -- Eastern Cape Hares -- Physiology
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5670 , http://hdl.handle.net/10962/d1005355
- Description: Springhare are large, bipedal, nocturnal, herbivorous, burrowing rodents that are found in arid and semi-arid parts of southern and eastern Africa. In this thesis I examine the general ecology, biology and physiology of these animals in the Eastern Cape Province of South Africa. An investigation of their distribution and activity in the study site showed that springhare exhibit a preference for flat, open, recently disturbed habitat that is dominated by the grass Cynodon dactylon and the sedge Cyperus esculentus. These two species constitute a major proportion of their diet. The impact of spring hare on chicory and grazing is also discussed. Nightly activity generally peaks soon after dark and decreases in the 2-4 hour period before sunrise. This pattern is, however, modified by moonlight. Springhare typically respond to moonlight by reducing aboveground activity, shifting their activity to dark moonless periods of the night, and by reducing their use of open space. Contrary to earlier reports, springhare utilise several different burrow systems spread over large areas. They regularly change burrow systems and seldom spend more than a few consecutive days in each. Springhare do not appear to defend territories but recently used burrows appear to be avoided by conspecifics. Males and females on average use a similar number of burrows, scattered over similar sized areas. Burrows are shown to provide a stable microclimate of moderate temperature and high humidity throughout the year. Reproduction is continuous and there is no synchronised breeding season. The ability to reproduce throughout the year is attributed primarily to their ability to utilise subterranean food stores. The overall reproductive strategy of springhare (a single young with long gestation and weaning) is unusual for a mammal of this size but may be linked to low levels of adult and juvenile mortality. Physiologically, springhare are reasonably well adapted to life in hot, arid environments. They produce a concentrated urine, exhibit a high tolerance to dehydration, are good osmoregulators capable of maintaining plasma volume, osmolality and ion balance over long periods of water deprivation, and are able to produce dry faeces. They are also good thermoregulators at low ambient temperatures, which are usually encountered at night, but are poor thermoregulators at high ambient temperatures, which they avoid behaviourally.
- Full Text:
- Date Issued: 2001
The effect of photoperiod on some aspects of reproduction in a Southern African rodent : the pouched mouse (Saccostomus Campestris)
- Authors: Gray, Janine
- Date: 2001
- Subjects: Mice -- Reproduction Antechinus -- Africa, Southern
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5676 , http://hdl.handle.net/10962/d1005361
- Description: The pouched mouse, Saccostomus campestris is widely distributed south of the Sahara, inhabiting both subtropical and tropical latitudes and a number of different biotic zones, where it breeds seasonally. In North temperate latitudes, reproduction in small mammals is controlled by photoperiod however this cue becomes less influential as latitude decreases towards the equator. The aim of the present study is to establish the role of photoperiod in the environmental control of reproduction in a seasonally breeding small mammal at low latitudes in a highly unpredictable environment. Spermatogenesis of domesticated and Fl-generation pouched mice was not inhibited by short daylength while decreasing daylength significantly affected the oestrous cycle of adult domesticated female pouched mice. Photoperiod had little effect on the oestrous cycle of F I-generation females while a possible inherent circannual endogenous rhythm controlled inhibition of reproduction in these females. Body mass of male and female juvenile pouched mice was consistently lower in short daylength and in juvenile female pouched mice the onset of fertility may be weight-dependent. The attainment of sexual maturity of domesticated and FIlF2-generation females was retarded but not halted in short daylength and females in long daylength reached puberty 7.8 - 10.2 days earlier. Short daylength also lengthened the interval between vaginal perforation and first oestrus. Puberty in juvenile females was age-dependent as both domesticated and FIlF2-generation males attained puberty at 50 days of age, although fewer males were fertile in long daylength than short daylength. Although litter size of pouched mice was smaller in short daylength for both domesticated and wildcaught females this was not due to a reduction in the ovulation rate. Domesticated females had significantly larger litters than wild-caught females. Male and female pouched mice have evolved different reproductive strategies as males become sexually mature at the same age irrespective of photoperiod and remain fertile throughout the year. In contrast, females tend to be more complex as juveniles delay reproductive maturity and adults become nonreproductive in short daylength. However, in the presence of a fertile male and if environmental conditions are favourable, in short daylength, females can become reproductively active within approximately 3 days. Thus, although the pouched mouse has adopted a purely opportunistic reproductive strategy, vestiges of photoresponsiveness are still present in the female. The seasonality exhibited in the wild is therefore due to the female. Pouched mice live in a highly unpredictable environment so the sole use of photoperiod to regulate reproduction would be disadvantageous.
- Full Text:
- Date Issued: 2001
- Authors: Gray, Janine
- Date: 2001
- Subjects: Mice -- Reproduction Antechinus -- Africa, Southern
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5676 , http://hdl.handle.net/10962/d1005361
- Description: The pouched mouse, Saccostomus campestris is widely distributed south of the Sahara, inhabiting both subtropical and tropical latitudes and a number of different biotic zones, where it breeds seasonally. In North temperate latitudes, reproduction in small mammals is controlled by photoperiod however this cue becomes less influential as latitude decreases towards the equator. The aim of the present study is to establish the role of photoperiod in the environmental control of reproduction in a seasonally breeding small mammal at low latitudes in a highly unpredictable environment. Spermatogenesis of domesticated and Fl-generation pouched mice was not inhibited by short daylength while decreasing daylength significantly affected the oestrous cycle of adult domesticated female pouched mice. Photoperiod had little effect on the oestrous cycle of F I-generation females while a possible inherent circannual endogenous rhythm controlled inhibition of reproduction in these females. Body mass of male and female juvenile pouched mice was consistently lower in short daylength and in juvenile female pouched mice the onset of fertility may be weight-dependent. The attainment of sexual maturity of domesticated and FIlF2-generation females was retarded but not halted in short daylength and females in long daylength reached puberty 7.8 - 10.2 days earlier. Short daylength also lengthened the interval between vaginal perforation and first oestrus. Puberty in juvenile females was age-dependent as both domesticated and FIlF2-generation males attained puberty at 50 days of age, although fewer males were fertile in long daylength than short daylength. Although litter size of pouched mice was smaller in short daylength for both domesticated and wildcaught females this was not due to a reduction in the ovulation rate. Domesticated females had significantly larger litters than wild-caught females. Male and female pouched mice have evolved different reproductive strategies as males become sexually mature at the same age irrespective of photoperiod and remain fertile throughout the year. In contrast, females tend to be more complex as juveniles delay reproductive maturity and adults become nonreproductive in short daylength. However, in the presence of a fertile male and if environmental conditions are favourable, in short daylength, females can become reproductively active within approximately 3 days. Thus, although the pouched mouse has adopted a purely opportunistic reproductive strategy, vestiges of photoresponsiveness are still present in the female. The seasonality exhibited in the wild is therefore due to the female. Pouched mice live in a highly unpredictable environment so the sole use of photoperiod to regulate reproduction would be disadvantageous.
- Full Text:
- Date Issued: 2001
The effects of melatonin on the testis, epididymis and sperm physiology of the Wistar rat
- Authors: Gwayi, Noluzuko
- Date: 2001
- Subjects: Rats as laboratory animals , Rats -- physiology , Spermatozoa , Melatonin , Testis , Epididymis
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5681 , http://hdl.handle.net/10962/d1005366 , Rats as laboratory animals , Rats -- physiology , Spermatozoa , Melatonin , Testis , Epididymis
- Description: Melatonin is a product of the pineal gland and is postulated to play an antigonadotropic role in the reproductive system of mammals. The reproductive system of non-seasonally breeding mammals is believed to be not as responsive to melatonin treatment as that of seasonally breeding mammals. Recently, there has been increasing support from in vivo and in vitro studies, for the hypothesis that melatonin has negative effects on sperm physiology, especially on sperm motility. High and/or low seminal concentrations of melatonin have been associated with abnormalities in human sperm motility and concentration. In this study, I examined the effects of melatonin on the testis, epididymis and sperm physiology, using in vivo and in vitro experiments, in a non-seasonally breeding mammal. Treatment, in vivo, with exogenous melatonin for six weeks did not inhibit testosterone production or spermatogenesis, nor did it affect the mass of the testes and epididymides at dissection, the concentration the morphology of speimatozoa. However, melatonin in vivo had a small, but significant negative effect on sperm motility and sperm motility index. In vitro incubation of spermatozoa Fith melatonin reduced the percentage (%) of forward progressive movement (fpm), increased the % reduction in fpm, reduced the vigor or quality of sperm motility, reduced the sperm motility index, and delayed and/or prolonged the transition of one pattern of sperm motility to the subsequent patterns. Melatonin increased the pH of the culture medium, and the increased pH, and the ethanol utilized as a solvent for melatonin, both negatively affected all the sperm motility parameters that were assessed in my study. The effects of ethanol increased with time, and the effects of pH increased with both time and increasing pH. Melatonin in vitro did not inhibit capacitation and the acrosome reaction, but it delayed the onset and the progression of capacitation and the acrosome reaction. These results suggest that while melatonin did not inhibit spermatogenesis in the Wistar rat, it may influence sperm motility. Therefore, the presence of high concentrations of melatonin in the reproductive fluids may inhibit sperm motility. With further detailed research, melatonin may have a potential use as a contraceptive drug.
- Full Text:
- Date Issued: 2001
- Authors: Gwayi, Noluzuko
- Date: 2001
- Subjects: Rats as laboratory animals , Rats -- physiology , Spermatozoa , Melatonin , Testis , Epididymis
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5681 , http://hdl.handle.net/10962/d1005366 , Rats as laboratory animals , Rats -- physiology , Spermatozoa , Melatonin , Testis , Epididymis
- Description: Melatonin is a product of the pineal gland and is postulated to play an antigonadotropic role in the reproductive system of mammals. The reproductive system of non-seasonally breeding mammals is believed to be not as responsive to melatonin treatment as that of seasonally breeding mammals. Recently, there has been increasing support from in vivo and in vitro studies, for the hypothesis that melatonin has negative effects on sperm physiology, especially on sperm motility. High and/or low seminal concentrations of melatonin have been associated with abnormalities in human sperm motility and concentration. In this study, I examined the effects of melatonin on the testis, epididymis and sperm physiology, using in vivo and in vitro experiments, in a non-seasonally breeding mammal. Treatment, in vivo, with exogenous melatonin for six weeks did not inhibit testosterone production or spermatogenesis, nor did it affect the mass of the testes and epididymides at dissection, the concentration the morphology of speimatozoa. However, melatonin in vivo had a small, but significant negative effect on sperm motility and sperm motility index. In vitro incubation of spermatozoa Fith melatonin reduced the percentage (%) of forward progressive movement (fpm), increased the % reduction in fpm, reduced the vigor or quality of sperm motility, reduced the sperm motility index, and delayed and/or prolonged the transition of one pattern of sperm motility to the subsequent patterns. Melatonin increased the pH of the culture medium, and the increased pH, and the ethanol utilized as a solvent for melatonin, both negatively affected all the sperm motility parameters that were assessed in my study. The effects of ethanol increased with time, and the effects of pH increased with both time and increasing pH. Melatonin in vitro did not inhibit capacitation and the acrosome reaction, but it delayed the onset and the progression of capacitation and the acrosome reaction. These results suggest that while melatonin did not inhibit spermatogenesis in the Wistar rat, it may influence sperm motility. Therefore, the presence of high concentrations of melatonin in the reproductive fluids may inhibit sperm motility. With further detailed research, melatonin may have a potential use as a contraceptive drug.
- Full Text:
- Date Issued: 2001
The mandibular gland secretions and ovarial development of worker honeybees (Apis Mellifera) in the Eastern Cape Province of South Africa
- Authors: Reece, Sacha Louise
- Date: 2001
- Subjects: Honeybee -- South Africa -- Eastern Cape , Honeybee -- Behavior , Honeybee -- Physiology
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5729 , http://hdl.handle.net/10962/d1005415 , Honeybee -- South Africa -- Eastern Cape , Honeybee -- Behavior , Honeybee -- Physiology
- Description: The Eastern Cape is an area in which Apis mellifera capensis, A. m. scutellata and their hybrid are known to naturally occur. I investigated the mandibular gland profiles and ovarial development of queenright workers from 4 localities. Their queens were then removed to determine how these aspects changed upon queen loss. In addition, drifted bees were analysed in the same way to determine how these factors changed once they had gained entry to a foreign hive. The queenright bees, form all 4 localities were found to have 9HDA as the most abundant of the 5 fatty acids measured and all localities had small percentages of 9ODA in their mandibular gland secretions. This resulted in relatively high queenright 9ODA:10HDA and 9HDA:10HDAA ratios. Despite this the percentage of bees with undeveloped ovaries was consistent with their queenright status. The mean values of these 2 ratios were significantly higher in the bees from East London and Cradock than those from Port Elizabeth. Steynsburg's bees were intermediate in this regard. Upon queen loss, the bees from all 4 localities had an increase in the percentage of 9ODA but the other compound changes in varying ways. East London's bees were the only ones not to become significantly more queen-like after queen loss. After 14 days without a queen, the mean values of these 2 ratios were much higher in the bees from Port Elizabeth than those from the other localities. Certain individuals from Port Elizabeth had values of these ratios that exceeded those found in A. m. capensis queens. Port Elizabeth was the only locality to display any surrogate queens and exhibited the highest increase in the number of bees with partially or fully developed ovaries. While certain individuals from the other localities had values of these ratios that exceeded these values reported in A. m. scutellata queens, Steynsburg's bees were the only ones that did increase in in terms of the number of bees with developed ovaries subsequent. The bees from Steynsburg were shown to suppress the mandibular gland and ovarial development of drifters from Port Elizabeth while bees from East London did not.
- Full Text:
- Date Issued: 2001
- Authors: Reece, Sacha Louise
- Date: 2001
- Subjects: Honeybee -- South Africa -- Eastern Cape , Honeybee -- Behavior , Honeybee -- Physiology
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5729 , http://hdl.handle.net/10962/d1005415 , Honeybee -- South Africa -- Eastern Cape , Honeybee -- Behavior , Honeybee -- Physiology
- Description: The Eastern Cape is an area in which Apis mellifera capensis, A. m. scutellata and their hybrid are known to naturally occur. I investigated the mandibular gland profiles and ovarial development of queenright workers from 4 localities. Their queens were then removed to determine how these aspects changed upon queen loss. In addition, drifted bees were analysed in the same way to determine how these factors changed once they had gained entry to a foreign hive. The queenright bees, form all 4 localities were found to have 9HDA as the most abundant of the 5 fatty acids measured and all localities had small percentages of 9ODA in their mandibular gland secretions. This resulted in relatively high queenright 9ODA:10HDA and 9HDA:10HDAA ratios. Despite this the percentage of bees with undeveloped ovaries was consistent with their queenright status. The mean values of these 2 ratios were significantly higher in the bees from East London and Cradock than those from Port Elizabeth. Steynsburg's bees were intermediate in this regard. Upon queen loss, the bees from all 4 localities had an increase in the percentage of 9ODA but the other compound changes in varying ways. East London's bees were the only ones not to become significantly more queen-like after queen loss. After 14 days without a queen, the mean values of these 2 ratios were much higher in the bees from Port Elizabeth than those from the other localities. Certain individuals from Port Elizabeth had values of these ratios that exceeded those found in A. m. capensis queens. Port Elizabeth was the only locality to display any surrogate queens and exhibited the highest increase in the number of bees with partially or fully developed ovaries. While certain individuals from the other localities had values of these ratios that exceeded these values reported in A. m. scutellata queens, Steynsburg's bees were the only ones that did increase in in terms of the number of bees with developed ovaries subsequent. The bees from Steynsburg were shown to suppress the mandibular gland and ovarial development of drifters from Port Elizabeth while bees from East London did not.
- Full Text:
- Date Issued: 2001
The mandibular gland secretions of the Cape honeybee (Apis mellifera capensis ESCH.) : factors affecting the production of the chemical signal and implications for further development of beekeeping in South Africa
- Authors: Jones, Georgina Elizabeth
- Date: 2001
- Subjects: Honeybee Honeybee -- Physiology
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5730 , http://hdl.handle.net/10962/d1005416
- Description: The chemical composition of the mandibular gland extracts of Apis mellifera capensis virgin queens was analysed by gas chromatography-mass spectroscopy. Thirty-seven compounds from various chemical groups including aliphatic and aromatic acids and diacids, phenols, alkanes, amino acids and sugars were identified. Among the identified compounds were the queen mandibular pheromone components 9ODA, 9HDA, HVA and HOB and the other aliphatic acids and phenols considered to be the major components of A.m. capensis mandibular glands. Ontogenetic changes in the concentration of the mandibular gland secretions of virgin queens were largely quantitative in nature with the total volume and that of most of the compounds increasing with queen age. The final level of 9ODA is reached at the premating stage, approximately three days after emergence, when it comprises approximately 87% of the major constituents of the mandibular gland signal. Hostile reactions by workers towards introduced virgin queens can be correlated to the relative proportion of 9ODA present in the mandibular gland secretions. This seems to indicate that it is the complete spectrum of the signal and not individual compounds that determine worker reaction towards introduced queens. Keeping queens singly, with or without workers, in an incubator and in small mating nucleus hives proved to be the most successful methods of queen rearing in respect to survival rate in A.m. capensis. The presence of workers during the ageing of virgin queens was found to significantly affect the chemical composition of the mandibular gland secretions of queens. The reaction of workers towards introduced virgin queens reared under different holding conditions varied, with queens reared with workers eliciting significantly less hostile reactions from workers than those reared without workers. Mated queens from five localities in the Eastern Cape were characterised on the basis of the chemical composition of their mandibular gland secretions and the ratio of 9ODA:10HDA. No significant differences were detected and none of the queens sampled could be considered to be A.m. capensis based on their mandibular gland signal. The findings of this study provide baseline data for the development of a queen-rearing program tailored to the specific requirements of A.m. capensis.
- Full Text:
- Date Issued: 2001
- Authors: Jones, Georgina Elizabeth
- Date: 2001
- Subjects: Honeybee Honeybee -- Physiology
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5730 , http://hdl.handle.net/10962/d1005416
- Description: The chemical composition of the mandibular gland extracts of Apis mellifera capensis virgin queens was analysed by gas chromatography-mass spectroscopy. Thirty-seven compounds from various chemical groups including aliphatic and aromatic acids and diacids, phenols, alkanes, amino acids and sugars were identified. Among the identified compounds were the queen mandibular pheromone components 9ODA, 9HDA, HVA and HOB and the other aliphatic acids and phenols considered to be the major components of A.m. capensis mandibular glands. Ontogenetic changes in the concentration of the mandibular gland secretions of virgin queens were largely quantitative in nature with the total volume and that of most of the compounds increasing with queen age. The final level of 9ODA is reached at the premating stage, approximately three days after emergence, when it comprises approximately 87% of the major constituents of the mandibular gland signal. Hostile reactions by workers towards introduced virgin queens can be correlated to the relative proportion of 9ODA present in the mandibular gland secretions. This seems to indicate that it is the complete spectrum of the signal and not individual compounds that determine worker reaction towards introduced queens. Keeping queens singly, with or without workers, in an incubator and in small mating nucleus hives proved to be the most successful methods of queen rearing in respect to survival rate in A.m. capensis. The presence of workers during the ageing of virgin queens was found to significantly affect the chemical composition of the mandibular gland secretions of queens. The reaction of workers towards introduced virgin queens reared under different holding conditions varied, with queens reared with workers eliciting significantly less hostile reactions from workers than those reared without workers. Mated queens from five localities in the Eastern Cape were characterised on the basis of the chemical composition of their mandibular gland secretions and the ratio of 9ODA:10HDA. No significant differences were detected and none of the queens sampled could be considered to be A.m. capensis based on their mandibular gland signal. The findings of this study provide baseline data for the development of a queen-rearing program tailored to the specific requirements of A.m. capensis.
- Full Text:
- Date Issued: 2001
The role of a symbiotic bryozoan in the chemical ecology of a marine benthic predator-prey interaction
- Authors: Gray, Christopher Anthony
- Date: 2001
- Subjects: Marine animals , Marine ecology , Benthic animals
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5756 , http://hdl.handle.net/10962/d1005444 , Marine animals , Marine ecology , Benthic animals
- Description: The subtidal whelk Burnupena papyracea (Brugière) co-occurs with a voracious predator, the rock lobster Jasus lalandii (Milne Edwards), in situations where other potential prey are largely eliminated. This has been ascribed to a symbiotic bryozoan, Alcyonidium nodosum (O’Donoghue and de Watteville), which characteristically encrusts the shells of B. papyracea and deters feeding by Jasus. In this study it is shown that this is not due to physical effects of either induced physical defences in the bryozoan or increased shell strength due to the presence of the bryozoan. Neither spectroscopic screening of chemical extracts of the bryozoan nor analysis for volatile constituents revealed any apparent chemical components that are likely to deter feeding. Chemical extracts also failed to show larvicidal effects in a standard toxicity assay using the brine shrimp Artemia salina (Leach). Despite this, bioassays using individual Jasus indicated a chemical basis for feeding deterrence. The assays were run separately on three sets of Jasus and some repeats of assays gave contradictory results. However, assays showing no significant effect of treatment occurred with moulting Jasus, involved very low overall feeding rates and so gave a less convincing result. In other assays Jasus always avoided Burnupena papyracea with live Alcyonidium encrusting the shell, and food pellets containing Alcyonidium or an Alcyonidium extract. Significant preferences were shown for an unencrusted whelk, B. cincta (Röding), over B. papyracea; for B. papyracea with the bryozoan scraped off over natural B. papyracea; for B. papyracea on which the bryozoans had been killed with liquid nitrogen over untreated B. papyracea; and for food pellets prepared from ground, dried mussel over pellets prepared with dried mussel mixed with A. nodosum or its crude organic extract. It is concluded that the protection which Alcyonidium confers on Burnupena papyracea does have a chemical basis, but that the chemical responsible is either present in only trace quantities, or that it is a structurally unremarkable compound which is distasteful to Jasus. This work highlights both the advantages of using ecologically relevant bioassays (positive results when standard techniques give a negative result) and also the disadvantages (logistic constraints on sample sizes when using large test animals and individual variability in a relatively sophisticated test animal).
- Full Text:
- Date Issued: 2001
- Authors: Gray, Christopher Anthony
- Date: 2001
- Subjects: Marine animals , Marine ecology , Benthic animals
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5756 , http://hdl.handle.net/10962/d1005444 , Marine animals , Marine ecology , Benthic animals
- Description: The subtidal whelk Burnupena papyracea (Brugière) co-occurs with a voracious predator, the rock lobster Jasus lalandii (Milne Edwards), in situations where other potential prey are largely eliminated. This has been ascribed to a symbiotic bryozoan, Alcyonidium nodosum (O’Donoghue and de Watteville), which characteristically encrusts the shells of B. papyracea and deters feeding by Jasus. In this study it is shown that this is not due to physical effects of either induced physical defences in the bryozoan or increased shell strength due to the presence of the bryozoan. Neither spectroscopic screening of chemical extracts of the bryozoan nor analysis for volatile constituents revealed any apparent chemical components that are likely to deter feeding. Chemical extracts also failed to show larvicidal effects in a standard toxicity assay using the brine shrimp Artemia salina (Leach). Despite this, bioassays using individual Jasus indicated a chemical basis for feeding deterrence. The assays were run separately on three sets of Jasus and some repeats of assays gave contradictory results. However, assays showing no significant effect of treatment occurred with moulting Jasus, involved very low overall feeding rates and so gave a less convincing result. In other assays Jasus always avoided Burnupena papyracea with live Alcyonidium encrusting the shell, and food pellets containing Alcyonidium or an Alcyonidium extract. Significant preferences were shown for an unencrusted whelk, B. cincta (Röding), over B. papyracea; for B. papyracea with the bryozoan scraped off over natural B. papyracea; for B. papyracea on which the bryozoans had been killed with liquid nitrogen over untreated B. papyracea; and for food pellets prepared from ground, dried mussel over pellets prepared with dried mussel mixed with A. nodosum or its crude organic extract. It is concluded that the protection which Alcyonidium confers on Burnupena papyracea does have a chemical basis, but that the chemical responsible is either present in only trace quantities, or that it is a structurally unremarkable compound which is distasteful to Jasus. This work highlights both the advantages of using ecologically relevant bioassays (positive results when standard techniques give a negative result) and also the disadvantages (logistic constraints on sample sizes when using large test animals and individual variability in a relatively sophisticated test animal).
- Full Text:
- Date Issued: 2001
Tolerance of selected riverine indigenous macroinvertebrates from the Sabie River (Mpumalanga), and Buffalo River (Eastern Cape) to complex saline kraft and textile effluents
- Authors: Zokufa, T S
- Date: 2001
- Subjects: Water quality management -- South Africa -- Sabie River , Water -- South Africa -- Analysis , Water -- Toxicology -- South Africa , Mayflies -- South Africa , Freshwater invertebrates -- South Africa -- Ecology
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5787 , http://hdl.handle.net/10962/d1005475
- Description: Whole Effluent Toxicity (WET) testing has been identified as one of the tools in the management of complex effluents in aquatic ecosystems. In South Africa, toxicity testing has not been required for regulatory purposes. Recently, the Department of Water Affairs and Forestry has adopted WET testing as a tool to evaluate the suitability of hazardous effluent for discharge into receiving environments. This has necessitated suitable procedures to be established for use in the South African situation. With the implementation of the new National Water Act (No 36 of 1998), industries have to comply with set standards to protect the aquatic environment. However, the South African Water Quality Guidelines for Aquatic Ecosystems have been set using international toxicity data, and it is not known if they are comparable with South African conditions. The aim of this study was to investigate the tolerances of selected indigenous riverine invertebrates to complex saline effluents. The study investigated the effects of kraft mill effluent to Tricorythus tinctus, a tricorythid mayfly from the Sabie River, Mpumalanga, and the effects of a textile effluent to baetid mayflies of the Buffalo River, Eastern Cape. Indigenous riverine invertebrates were chosen as test organisms, as there is no toxicity data in South Africa which could be used to evaluate the level of protection afforded by the South African Water Quality Guidelines for Aquatic Ecosystems. The use of indigenous riverine invertebrates added the challenge of variability of a wild population, and the use of a complex effluent as toxicant added the variability of effluent composition. In this study, WET testing was used to determine the dilution of whole effluents required for discharge. Hazard-based guidelines were developed for the disposal of kraft and textile effluents. The level of environmental hazard posed by different effluent concentrations was ranked, and was related to the River Health Class. This indicated effluent concentrations that may be allowed to enter the aquatic environment, e.g. 3% effluent concentration guideline for both general kraft effluent and general textile effluent for the protection of a Class A river. This approach could contribute to the use of an Environmental Risk Assessment, approach for the management of complex effluents. A number of acute 96 hour toxicity tests were conducted following an unreplicated regression design, using kraft and textile effluents as toxicants, mayfly nymphs as test organisms, and river water as diluent and control. Test organisms were sampled from unimpacted, flowing-water riffle areas, and were exposed in recirculating artificial streams (or channels) to a range of effluent concentrations. Mortality was selected as end-point and observed twice daily. The experimental results showed the variability and acute toxicity of both kraft and textile mill effluents. Baetids were more sensitive (mean LC50=16% effluent concentration) to General Textile Effluent (GTE), but less sensitive to Post Irrigation Textile Effluent (PITE). Textile effluent (PITE) held in a holding dam were therefore less variable and less toxic; suggesting that stabilization of the effluent could have contributed to reduced toxicity. Effluent composition, e.g. higher calcium levels, may also have contributed to lowering toxicity. T. tinctus was sensitive to kraft effluents, but showed less variable responses to Irrigation Kraft Effluent than General Kraft Effluent. Toxicity test data indicated that GKE, IKE and GTE should not enter the aquatic environment without treatment, as they can cause adverse effects to aquatic biota. Both kraft and textile effluents must therefore be treated before discharge. Different responses to different effluent batches were probably due to effluent variability. The use of indigenous organisms, and not a standard laboratory organism, could also have contributed to variability. A hazard-based approach could be useful, as it will provide a consistent basis for deciding on the acceptability of impacts, while allowing natural site-specific differences to be taken into account.
- Full Text:
- Date Issued: 2001
- Authors: Zokufa, T S
- Date: 2001
- Subjects: Water quality management -- South Africa -- Sabie River , Water -- South Africa -- Analysis , Water -- Toxicology -- South Africa , Mayflies -- South Africa , Freshwater invertebrates -- South Africa -- Ecology
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5787 , http://hdl.handle.net/10962/d1005475
- Description: Whole Effluent Toxicity (WET) testing has been identified as one of the tools in the management of complex effluents in aquatic ecosystems. In South Africa, toxicity testing has not been required for regulatory purposes. Recently, the Department of Water Affairs and Forestry has adopted WET testing as a tool to evaluate the suitability of hazardous effluent for discharge into receiving environments. This has necessitated suitable procedures to be established for use in the South African situation. With the implementation of the new National Water Act (No 36 of 1998), industries have to comply with set standards to protect the aquatic environment. However, the South African Water Quality Guidelines for Aquatic Ecosystems have been set using international toxicity data, and it is not known if they are comparable with South African conditions. The aim of this study was to investigate the tolerances of selected indigenous riverine invertebrates to complex saline effluents. The study investigated the effects of kraft mill effluent to Tricorythus tinctus, a tricorythid mayfly from the Sabie River, Mpumalanga, and the effects of a textile effluent to baetid mayflies of the Buffalo River, Eastern Cape. Indigenous riverine invertebrates were chosen as test organisms, as there is no toxicity data in South Africa which could be used to evaluate the level of protection afforded by the South African Water Quality Guidelines for Aquatic Ecosystems. The use of indigenous riverine invertebrates added the challenge of variability of a wild population, and the use of a complex effluent as toxicant added the variability of effluent composition. In this study, WET testing was used to determine the dilution of whole effluents required for discharge. Hazard-based guidelines were developed for the disposal of kraft and textile effluents. The level of environmental hazard posed by different effluent concentrations was ranked, and was related to the River Health Class. This indicated effluent concentrations that may be allowed to enter the aquatic environment, e.g. 3% effluent concentration guideline for both general kraft effluent and general textile effluent for the protection of a Class A river. This approach could contribute to the use of an Environmental Risk Assessment, approach for the management of complex effluents. A number of acute 96 hour toxicity tests were conducted following an unreplicated regression design, using kraft and textile effluents as toxicants, mayfly nymphs as test organisms, and river water as diluent and control. Test organisms were sampled from unimpacted, flowing-water riffle areas, and were exposed in recirculating artificial streams (or channels) to a range of effluent concentrations. Mortality was selected as end-point and observed twice daily. The experimental results showed the variability and acute toxicity of both kraft and textile mill effluents. Baetids were more sensitive (mean LC50=16% effluent concentration) to General Textile Effluent (GTE), but less sensitive to Post Irrigation Textile Effluent (PITE). Textile effluent (PITE) held in a holding dam were therefore less variable and less toxic; suggesting that stabilization of the effluent could have contributed to reduced toxicity. Effluent composition, e.g. higher calcium levels, may also have contributed to lowering toxicity. T. tinctus was sensitive to kraft effluents, but showed less variable responses to Irrigation Kraft Effluent than General Kraft Effluent. Toxicity test data indicated that GKE, IKE and GTE should not enter the aquatic environment without treatment, as they can cause adverse effects to aquatic biota. Both kraft and textile effluents must therefore be treated before discharge. Different responses to different effluent batches were probably due to effluent variability. The use of indigenous organisms, and not a standard laboratory organism, could also have contributed to variability. A hazard-based approach could be useful, as it will provide a consistent basis for deciding on the acceptability of impacts, while allowing natural site-specific differences to be taken into account.
- Full Text:
- Date Issued: 2001
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