Botanical inventory and phenology in relation to foraging behaviour of the Cape honeybees (Apis Mellifera Capensis) at a site in the Eastern Cape, South Africa
- Authors: Merti, Admassu Addi
- Date: 2003
- Subjects: Fynbos -- South Africa -- Eastern Cape , Honeybee -- South Africa -- Eastern Cape , Honey plants -- South Africa -- Eastern Cape , Honeybee -- South Africa -- Eastern Cape -- Food , Plant ecology -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4214 , http://hdl.handle.net/10962/d1003783 , Fynbos -- South Africa -- Eastern Cape , Honeybee -- South Africa -- Eastern Cape , Honey plants -- South Africa -- Eastern Cape , Honeybee -- South Africa -- Eastern Cape -- Food , Plant ecology -- South Africa -- Eastern Cape
- Description: From an apicultural point of view the Cape fynbos is under-utilised and our knowledge of its utilization by the Cape honeybees is incomplete. The key aim of this study was to test the hypothesis that the Cape honeybees utilize the fynbos species as the preferred source of nectar and pollen. Subsidiary aims included distinguishing vegetation communities in the area, identifying pollen and nectar sources, the relationship between brood population and seasonal pollen collection patterns, examining the effect of meteorological factors on pollen collection. The study site was on Rivendell Farm within the Eastern Cape Albany district: an area of high species richness. A checklist of vascular plant species was produced revealing 97 families, 271 genera and 448 species. A classification by two-way indicator species (TWINSPAN) recognized seven vegetation communities: Forest, Bush clumps, Acacia savanna, Grassland, Grassy fynbos, Fynbos and Shrubland. Direct field observations of the foraging of Cape honeybees identified 54 nectar and pollen source plant species. Honeybee pollen loads trapped from four colonies of hives identified 37 pollen source plants of which Metalasia muricata, Eucalyptus grandis, Eucalyptus camaldulensis, Erica chamissonis, Helichrysum odoratissimum, Helichrysum anomalum, Crassula cultrata and Acacia longifolia were the predominant pollen source plants. It was also found that 60% of pollen yield derived from fynbos vegetation. The pollen source plants came from both Cape endemic and from nonendemic species. Thus we reject the hypothesis that Cape honeybees selectively forage fynbos species as a preferred source of pollen and nectar. The examination of the effect of temperature, wind-speed and temperature on pollen collection activity of honeybees revealed that: a temperature range of between 14°C to 26°C was optimal for pollen collection; wind speeds of up to 4m/s were conducive for pollen collection; relative humidity was found to have no significant influence on pollen collection. Pollen collection and brood rearing patterns are positively correlated with flowering intensities, but we found in our Eastern Cape study site that brood rearing was not limited to the spring flowering season but did extend to the end of summer. In order to determine the available nectar yield of common plant species hourly secretion of nectar volumes was measured for 24 hours to determine the variation of available nectar during different times of the day. In all nectar producing species the nectar volume was high in the early morning and declined as the day progressed. We found that the volume of available nectar was affected by prevailing temperature and humidity around the flowers.
- Full Text:
- Date Issued: 2003
- Authors: Merti, Admassu Addi
- Date: 2003
- Subjects: Fynbos -- South Africa -- Eastern Cape , Honeybee -- South Africa -- Eastern Cape , Honey plants -- South Africa -- Eastern Cape , Honeybee -- South Africa -- Eastern Cape -- Food , Plant ecology -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4214 , http://hdl.handle.net/10962/d1003783 , Fynbos -- South Africa -- Eastern Cape , Honeybee -- South Africa -- Eastern Cape , Honey plants -- South Africa -- Eastern Cape , Honeybee -- South Africa -- Eastern Cape -- Food , Plant ecology -- South Africa -- Eastern Cape
- Description: From an apicultural point of view the Cape fynbos is under-utilised and our knowledge of its utilization by the Cape honeybees is incomplete. The key aim of this study was to test the hypothesis that the Cape honeybees utilize the fynbos species as the preferred source of nectar and pollen. Subsidiary aims included distinguishing vegetation communities in the area, identifying pollen and nectar sources, the relationship between brood population and seasonal pollen collection patterns, examining the effect of meteorological factors on pollen collection. The study site was on Rivendell Farm within the Eastern Cape Albany district: an area of high species richness. A checklist of vascular plant species was produced revealing 97 families, 271 genera and 448 species. A classification by two-way indicator species (TWINSPAN) recognized seven vegetation communities: Forest, Bush clumps, Acacia savanna, Grassland, Grassy fynbos, Fynbos and Shrubland. Direct field observations of the foraging of Cape honeybees identified 54 nectar and pollen source plant species. Honeybee pollen loads trapped from four colonies of hives identified 37 pollen source plants of which Metalasia muricata, Eucalyptus grandis, Eucalyptus camaldulensis, Erica chamissonis, Helichrysum odoratissimum, Helichrysum anomalum, Crassula cultrata and Acacia longifolia were the predominant pollen source plants. It was also found that 60% of pollen yield derived from fynbos vegetation. The pollen source plants came from both Cape endemic and from nonendemic species. Thus we reject the hypothesis that Cape honeybees selectively forage fynbos species as a preferred source of pollen and nectar. The examination of the effect of temperature, wind-speed and temperature on pollen collection activity of honeybees revealed that: a temperature range of between 14°C to 26°C was optimal for pollen collection; wind speeds of up to 4m/s were conducive for pollen collection; relative humidity was found to have no significant influence on pollen collection. Pollen collection and brood rearing patterns are positively correlated with flowering intensities, but we found in our Eastern Cape study site that brood rearing was not limited to the spring flowering season but did extend to the end of summer. In order to determine the available nectar yield of common plant species hourly secretion of nectar volumes was measured for 24 hours to determine the variation of available nectar during different times of the day. In all nectar producing species the nectar volume was high in the early morning and declined as the day progressed. We found that the volume of available nectar was affected by prevailing temperature and humidity around the flowers.
- Full Text:
- Date Issued: 2003
Symplasmic pathway in phloem loading and unloading in source and sink leaves of Zea mays L. as evidenced under normal and elevated CO₂ conditions
- Authors: Nogemane, Noluyolo
- Date: 2003
- Subjects: Phloem , Plant translocation , Plant cells and tissues , Corn -- Metabolsim
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4254 , http://hdl.handle.net/10962/d1007813
- Description: Zea mays plants kept at ambient (ca 375ppm) and elevated CO₂ (ca 650 to 700ppm) were used to examine the possibility of a symplasmic loading, unloading and transport pathway in dark-adapted and illuminated (200μmolm⁻²sec⁻¹ ) sink and source leaves. 5,6-carboxyfluorescein diacetate was introduced into the mesophyll cells and symplasmic transfer observed 3h after application. In sink and source leaves exposed to ambient CO₂ and illuminated at 200 molm-2sec-1, the fluorescence front was observed approximately 3cm from the point of application, while in dark-adapted plants, the fluorescence front was observed approximately 1cm from the point of application. Under elevated CO₂ conditions the fluorescence front in illuminated plants appeared to transport faster moving approximately 5cm from the point of application, and in dark-adapted plants, only 3cm from the point of application. Based on the increase in 5,6-CF accumulation under elevated CO₂ conditions, the present study suggests that there was an increase in capacity for assimilate loading and transport under elevated CO₂ conditions. In source leaves, 5,6-CFDA was taken up into the mesophyll cells, loaded symplasmically and transported basipetally. In sink leaves 5,6- CFDA was taken up from basal mesophyll and after symplasmic loading, was transported acropetally where it was offloaded into the younger immature sink region. Transport in the sieve tubes was confirmed by using aniline blue, which was applied 3h after 5,6-CF transport. Aniline blue coupled with 5,6-CF transport studies showed that the sieve tubes of both cross and longitudinal veins are involved in symplasmic unloading, loading and transport processes in sink and source leaves. Apoplasmic uptake of 5,6-CFDA by cut leaves showed that after apoplasmic transport via the transpiration stream, 5,6-CFDA was offioaded to the xylem parenchyma where it was metabolically cleaved , releasing fluorescent 5,6-CF into the xylem parenchyma. Transverse sections cut after 3h of uptake were observed after 120 and 180 min suggesting that a retrieval of solutes occurs from the xylem to the xylem parenchyma, bundle sheath, phloem parenchyma and to the th in-walled sieve tubes. It was not possible to determine if the thick-walled sieve tubes were involved or if they took up 5,6-CF. Given the available data on loading and offioading of assimilates in sink and source leaves respectively, this study demonstrated that a slow symplasmic pathway exists from the mesophyll to the phloem, and that offloading from the phloem in sink leaves can occur via a symplasmic route.
- Full Text:
- Date Issued: 2003
- Authors: Nogemane, Noluyolo
- Date: 2003
- Subjects: Phloem , Plant translocation , Plant cells and tissues , Corn -- Metabolsim
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4254 , http://hdl.handle.net/10962/d1007813
- Description: Zea mays plants kept at ambient (ca 375ppm) and elevated CO₂ (ca 650 to 700ppm) were used to examine the possibility of a symplasmic loading, unloading and transport pathway in dark-adapted and illuminated (200μmolm⁻²sec⁻¹ ) sink and source leaves. 5,6-carboxyfluorescein diacetate was introduced into the mesophyll cells and symplasmic transfer observed 3h after application. In sink and source leaves exposed to ambient CO₂ and illuminated at 200 molm-2sec-1, the fluorescence front was observed approximately 3cm from the point of application, while in dark-adapted plants, the fluorescence front was observed approximately 1cm from the point of application. Under elevated CO₂ conditions the fluorescence front in illuminated plants appeared to transport faster moving approximately 5cm from the point of application, and in dark-adapted plants, only 3cm from the point of application. Based on the increase in 5,6-CF accumulation under elevated CO₂ conditions, the present study suggests that there was an increase in capacity for assimilate loading and transport under elevated CO₂ conditions. In source leaves, 5,6-CFDA was taken up into the mesophyll cells, loaded symplasmically and transported basipetally. In sink leaves 5,6- CFDA was taken up from basal mesophyll and after symplasmic loading, was transported acropetally where it was offloaded into the younger immature sink region. Transport in the sieve tubes was confirmed by using aniline blue, which was applied 3h after 5,6-CF transport. Aniline blue coupled with 5,6-CF transport studies showed that the sieve tubes of both cross and longitudinal veins are involved in symplasmic unloading, loading and transport processes in sink and source leaves. Apoplasmic uptake of 5,6-CFDA by cut leaves showed that after apoplasmic transport via the transpiration stream, 5,6-CFDA was offioaded to the xylem parenchyma where it was metabolically cleaved , releasing fluorescent 5,6-CF into the xylem parenchyma. Transverse sections cut after 3h of uptake were observed after 120 and 180 min suggesting that a retrieval of solutes occurs from the xylem to the xylem parenchyma, bundle sheath, phloem parenchyma and to the th in-walled sieve tubes. It was not possible to determine if the thick-walled sieve tubes were involved or if they took up 5,6-CF. Given the available data on loading and offioading of assimilates in sink and source leaves respectively, this study demonstrated that a slow symplasmic pathway exists from the mesophyll to the phloem, and that offloading from the phloem in sink leaves can occur via a symplasmic route.
- Full Text:
- Date Issued: 2003
Confirmation of a slow symplasmic loading and unloading pathway in barley (Hordeum Vulgare L.) source and sink leaves
- Authors: Buwa, Lisa Valencia
- Date: 2003
- Subjects: Phloem , Plant translocation , Barley -- Metabolism
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4253 , http://hdl.handle.net/10962/d1007804
- Description: Visualization of the transport pathway in barley (Hordeum vulgare) leaves was carried out using a combination of aniline blue and a symplasmically transported fluorochrome, 5,6 carboxyfluorescein (5,6-CF). When applied to a source leaf, basipetal movement of 5,6-CF was observed after 3 h and the fluorochrome front was observed about 3-4cm away from the point of application. The fluorochrome was taken up into the symplasm of the mesophyll and was loaded into the bundle sheath cells and then subsequently the vascular parenchyma and finally into the sieve tubes. In sink leaves, acropetal movement was observed after 3 h and the fluorochrome had moved approximately 3 cm away from the point of application. Unloading of 5,6-CF occurred from all classes of longitudinal veins. Studies on solute retrieval showed that 5,6 CF-diacetate was transferred to xylem parenchyma where it was metabolized. 5,6-CF was then transferred from the xylem parenchyma to the vascular parenchyma cells, and it would appear that thick-walled sieve tubes were the first to show 5,6-CF labeling. Counterstaining with aniline blue demonstrates the presence of plasmodesmata and this suggests a potential symplasmic pathway from the mesophyll to the sieve tubes. Application of 5,6 CF-diacetate revealed a slow symplasmic pathway, which involved transfer of 5,6-CF, which was effected via plasmodesma.
- Full Text:
- Date Issued: 2003
- Authors: Buwa, Lisa Valencia
- Date: 2003
- Subjects: Phloem , Plant translocation , Barley -- Metabolism
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4253 , http://hdl.handle.net/10962/d1007804
- Description: Visualization of the transport pathway in barley (Hordeum vulgare) leaves was carried out using a combination of aniline blue and a symplasmically transported fluorochrome, 5,6 carboxyfluorescein (5,6-CF). When applied to a source leaf, basipetal movement of 5,6-CF was observed after 3 h and the fluorochrome front was observed about 3-4cm away from the point of application. The fluorochrome was taken up into the symplasm of the mesophyll and was loaded into the bundle sheath cells and then subsequently the vascular parenchyma and finally into the sieve tubes. In sink leaves, acropetal movement was observed after 3 h and the fluorochrome had moved approximately 3 cm away from the point of application. Unloading of 5,6-CF occurred from all classes of longitudinal veins. Studies on solute retrieval showed that 5,6 CF-diacetate was transferred to xylem parenchyma where it was metabolized. 5,6-CF was then transferred from the xylem parenchyma to the vascular parenchyma cells, and it would appear that thick-walled sieve tubes were the first to show 5,6-CF labeling. Counterstaining with aniline blue demonstrates the presence of plasmodesmata and this suggests a potential symplasmic pathway from the mesophyll to the sieve tubes. Application of 5,6 CF-diacetate revealed a slow symplasmic pathway, which involved transfer of 5,6-CF, which was effected via plasmodesma.
- Full Text:
- Date Issued: 2003
Effects of sustained Russian wheat aphid (Diuraphis noxia Mordvilko) feeding on leaf blades of wheat (Triticum aestivum L. cv Adamtas)
- Authors: Matsiliza, Babalwa
- Date: 2003
- Subjects: Russian wheat aphid Wheat -- Diseases and pests
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4213 , http://hdl.handle.net/10962/d1003782
- Description: Penetration of sink as well as source leaves of wheat plants by the Russian wheat aphid, Diuraphis noxia (Mordvilko) was investigated using light, fluorescence and transmission electron techniques, to determine the feeding strategies adopted by the aphid in penetrating and successfully feeding from the phloem, and to assess the structural effects of the probing and feeding behaviour of D. noxia on the feeding sites. Examination of aphid-infested sink, as well as source leaf tissue, showed that D.noxia probed in cells of the vascular bundle more frequently than mesophyll cells. Within the vascular bundle, thin-walled sieve tubes were visited (probed) more than the other cells. In sink leaf material, 68 of 82 (83%) stylets and stylet tracks encountered during the examination of 1000 serial sections (from 5 different plants) terminated in thin-walled sieve tubes and only 14 (17%) in thick-walled sieve tubes. Thin-walled sieve tubes were visited more significantly than thick-walled sieve tubes. However, examination of the aphid.,.infested sink leaf on a per centimetre basis, from the tip of the leaf, revealed that thick-walled sieve tubes in the area closest to the tip (0-2cm from the tip) were as attractive to the aphid as were thin-walled sieve tubes, with no significant difference in the number of times thick- and thin-walled sieve tubes were probed in this area. Some 2-4cm from the tip however, thinwalled sieve tubes were significantly more probed and therefore more attractive than thick-walled sieve tubes. Examination of 2000 serial sections using aphid-infested source leaf tissue, showed that the thin-walled sieve tubes were significantly more probed than thickwalled sieve tubes, along the whole leaf, expressed as a total of all leaves, as well as on a per centimetre basis along the length of the leaf, with 212 (95%) of 222 terminations within the thin-walled sieve tubes and only 10 (5%) in thick-walledsieve tubes. The aphid probed the small vascular bundles (loading bundles) many more times than intermediate or large transport vascular bundles, in sink as well as source leaf. Of a total of 82 stylets and stylet tracks encountered in sink leaf tissue, 31 terminated in small vascular bundles ang the remaining 28 and 16 were located within large and intermediate vascular bundles respectively. In source leaf tissue 121 of 222 stylets and stylet tracks encountered were associated with small vascular bundles and only 58 tracks and 43 tracks with intermediate and large vascular bundles, respectively. The effect of sustained RWA feeding on the transport capacity was examined after the application of 5,6 carboxyfluoresceine diacetate (5,6-CFDA) in control (sink and source leaf tissue) and aphid-infested (source) wheat leaves, using fluorescence microscopy. After 3h acropetal longitudinal transport of 5,6-CF had occurred in sink leaves in longitudinal veins, as well as a lateral transfer via cross veins and subsequent unloading into mesophyll cells close to the tip of the leaf was observed. In control leaf tissue, the fluorescence front was detected up to about 5cm from the point of application and was only associated with the phloem and not unloaded. In contrast, aphid-infested leaf tissue showed very little 5,6-CF transport, being limited to 2cm or less from the point of application. Structural damage to the phloem in general and to the sieve tubes in particular within of control and infested wheat leaves was investigated using transmission electron microscopy (TEM). In addition, leaf strips were mounted in aniline blue to visualise callose deposition using the fluorescence microscopy. At the TEM level. infested leaf tissue showed various abnormalities, which included destruction of cell contents, membrane damage and subsequent loss of cell contents. TEM studies suggest severe osmotic shock resulted from the aphid's probing. Examination of leaf tissue using fluorescence microscopy showed that there was very little characteristic aniline blue-stained callose visible in control leaf tissue, other than the thin diffuse patches along the sieve plates and punctate spots associated with pore plasmodesmatal areas and plasmodesmatal aggregates. In contrast, the aphid-infested leaf tissue was heavily callosed, with callose deposited not only within the phloem tissue but also in neighbouring vascular parE:}nchyma cells as well. The data collectively suggest that D. noxia feeds preferentially within thin-walled sieve tubes, within the small longitudinal vascular bundles in sink , as well source leaf tissue. Based upon the data presented here the thin-walled sieve tubes in the wheat leaf appear to be more attractive to the aphid and that they are probably more functional in terms of transport system and unlo?lding in sink leaves. Aniline blue stained leaf material that had previously hosted large aphid colonies showed evidence of extensive callose deposits 24 to 36h after the aphids were removed, suggesting that the aphids caused severe mechanical damage to the vascular tissue and mesohyll cells as well. Damage (transient or more permanent) and the subsequent deposition of wound callose, disrupted phloem transport and hence the export of photoassimilate from the leaves.
- Full Text:
- Date Issued: 2003
- Authors: Matsiliza, Babalwa
- Date: 2003
- Subjects: Russian wheat aphid Wheat -- Diseases and pests
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4213 , http://hdl.handle.net/10962/d1003782
- Description: Penetration of sink as well as source leaves of wheat plants by the Russian wheat aphid, Diuraphis noxia (Mordvilko) was investigated using light, fluorescence and transmission electron techniques, to determine the feeding strategies adopted by the aphid in penetrating and successfully feeding from the phloem, and to assess the structural effects of the probing and feeding behaviour of D. noxia on the feeding sites. Examination of aphid-infested sink, as well as source leaf tissue, showed that D.noxia probed in cells of the vascular bundle more frequently than mesophyll cells. Within the vascular bundle, thin-walled sieve tubes were visited (probed) more than the other cells. In sink leaf material, 68 of 82 (83%) stylets and stylet tracks encountered during the examination of 1000 serial sections (from 5 different plants) terminated in thin-walled sieve tubes and only 14 (17%) in thick-walled sieve tubes. Thin-walled sieve tubes were visited more significantly than thick-walled sieve tubes. However, examination of the aphid.,.infested sink leaf on a per centimetre basis, from the tip of the leaf, revealed that thick-walled sieve tubes in the area closest to the tip (0-2cm from the tip) were as attractive to the aphid as were thin-walled sieve tubes, with no significant difference in the number of times thick- and thin-walled sieve tubes were probed in this area. Some 2-4cm from the tip however, thinwalled sieve tubes were significantly more probed and therefore more attractive than thick-walled sieve tubes. Examination of 2000 serial sections using aphid-infested source leaf tissue, showed that the thin-walled sieve tubes were significantly more probed than thickwalled sieve tubes, along the whole leaf, expressed as a total of all leaves, as well as on a per centimetre basis along the length of the leaf, with 212 (95%) of 222 terminations within the thin-walled sieve tubes and only 10 (5%) in thick-walledsieve tubes. The aphid probed the small vascular bundles (loading bundles) many more times than intermediate or large transport vascular bundles, in sink as well as source leaf. Of a total of 82 stylets and stylet tracks encountered in sink leaf tissue, 31 terminated in small vascular bundles ang the remaining 28 and 16 were located within large and intermediate vascular bundles respectively. In source leaf tissue 121 of 222 stylets and stylet tracks encountered were associated with small vascular bundles and only 58 tracks and 43 tracks with intermediate and large vascular bundles, respectively. The effect of sustained RWA feeding on the transport capacity was examined after the application of 5,6 carboxyfluoresceine diacetate (5,6-CFDA) in control (sink and source leaf tissue) and aphid-infested (source) wheat leaves, using fluorescence microscopy. After 3h acropetal longitudinal transport of 5,6-CF had occurred in sink leaves in longitudinal veins, as well as a lateral transfer via cross veins and subsequent unloading into mesophyll cells close to the tip of the leaf was observed. In control leaf tissue, the fluorescence front was detected up to about 5cm from the point of application and was only associated with the phloem and not unloaded. In contrast, aphid-infested leaf tissue showed very little 5,6-CF transport, being limited to 2cm or less from the point of application. Structural damage to the phloem in general and to the sieve tubes in particular within of control and infested wheat leaves was investigated using transmission electron microscopy (TEM). In addition, leaf strips were mounted in aniline blue to visualise callose deposition using the fluorescence microscopy. At the TEM level. infested leaf tissue showed various abnormalities, which included destruction of cell contents, membrane damage and subsequent loss of cell contents. TEM studies suggest severe osmotic shock resulted from the aphid's probing. Examination of leaf tissue using fluorescence microscopy showed that there was very little characteristic aniline blue-stained callose visible in control leaf tissue, other than the thin diffuse patches along the sieve plates and punctate spots associated with pore plasmodesmatal areas and plasmodesmatal aggregates. In contrast, the aphid-infested leaf tissue was heavily callosed, with callose deposited not only within the phloem tissue but also in neighbouring vascular parE:}nchyma cells as well. The data collectively suggest that D. noxia feeds preferentially within thin-walled sieve tubes, within the small longitudinal vascular bundles in sink , as well source leaf tissue. Based upon the data presented here the thin-walled sieve tubes in the wheat leaf appear to be more attractive to the aphid and that they are probably more functional in terms of transport system and unlo?lding in sink leaves. Aniline blue stained leaf material that had previously hosted large aphid colonies showed evidence of extensive callose deposits 24 to 36h after the aphids were removed, suggesting that the aphids caused severe mechanical damage to the vascular tissue and mesohyll cells as well. Damage (transient or more permanent) and the subsequent deposition of wound callose, disrupted phloem transport and hence the export of photoassimilate from the leaves.
- Full Text:
- Date Issued: 2003
- «
- ‹
- 1
- ›
- »