Abstract. 1 Second instar Filippia gemina de Lotto scale insects are the preferred hosts of femal... more Abstract. 1 Second instar Filippia gemina de Lotto scale insects are the preferred hosts of female Coccophugus atrutus Compere larvae. These scale insects were found on their host plants, Chrysanthemoides monilifera Norlindh and Cliffortia strobilifera Mettenius, only at certain times during a 1 year sampling programme. 2 Late larval instars and prepupae of C.atratus, and a Metaphycus species, are the preferred hosts of male C.atratus larvae. These hosts, although they occurred on the same host plants as hosts for female C.atratus, were most numerous at different times during the sampling period. 3 The ratio of hosts suitable for C.atratus varied from a predominance of hosts suitable for females through to a predominance of hosts suitable for males. Sex ratios of adult C.atratus followed a similar trend but did not reflect, exactly, the ratio of available hosts. Differences in mortality between sexes and hyperparasitism may account for this anomaly. 4 Variable population sex ratios observed in C.atratus apparently result from the behaviour of individual females in which brood sex ratios are dependent on the relative availability of hosts for males and hosts for females. This behaviour, in turn, may result from variability in the host population structure but may also result from selection pressures operating at the time that heteronomous hyperparasitism evolved.
Cape porcupines (Hystrix africaeaustralis) appear to have an important influence on landscapes th... more Cape porcupines (Hystrix africaeaustralis) appear to have an important influence on landscapes through both biotic (foraging) and abiotic (soil turnover) impacts. Porcupine abundance and abiotic effects across the landscape were investigated in Nieuwoudtville, ...
<b>Supporting Raw Data</b> This excel contains supporting raw data for the manuscript... more <b>Supporting Raw Data</b> This excel contains supporting raw data for the manuscript, including: Sequence ID, collector information, date of pollen collection, Location of apiary, source of pollen<br> <b>DNA Data</b> This file contains the DNA sequence data to support the manuscript. The key for the pollen samples, including apiary location is contained in the raw data excel spreadsheet.From: Annalie Melin, Jonathan F Colville, Gregory D Duckworth, Res Altwegg, Ruhan Slabbert, Jeremy J Midgley, Mathieu Rouget &amp; John S Donaldson (2020) Diversity of pollen sources used by managed honey bees in variegated landscapes, Journal of Apicultural Research, DOI: 10.1080/00218839.2020.1750757<br>
Brood-site mutualisms represent extreme levels of reciprocal specialization between plants and in... more Brood-site mutualisms represent extreme levels of reciprocal specialization between plants and insect pollinators, raising questions about whether these mutualisms are mediated by volatile signals and whether these signals and insect responses to them covary geographically in a manner expected from coevolution. Cycads are an ancient plant lineage in which almost all extant species are pollinated through brood-site mutualisms with insects. We investigated whether volatile emissions and insect olfactory responses are matched across the distribution range of the African cycad Encephalartos villosus. This cycad species is pollinated by the same beetle species across its distribution, but cone volatile emissions are dominated by alkenes in northern populations, and by monoterpenes and a pyrazine compound in southern populations. In reciprocal choice experiments, insects chose the scent of cones from the local region over that of cones from the other region. Antennae of beetles from northern populations responded mainly to alkenes, while those of beetles from southern populations responded mainly to pyrazine. In bioassay experiments, beetles were most strongly attracted to alkenes in northern populations and to the pyrazine compound in southern populations. Geographical matching of cone volatiles and pollinator olfactory preference is consistent with coevolution in this specialized mutualism
Most pollination ecosystem services studies have focussed on wild pollinators and their dependenc... more Most pollination ecosystem services studies have focussed on wild pollinators and their dependence on natural floral resources adjacent to crop fields. However, managed pollinators depend on a mixture of floral resources that are spatially separated from the crop field. Here, we consider the supporting role these resources play as an ecosystem services provider to quantify the use and availability of floral resources, and to estimate their relative contribution to support pollination services of managed honeybees. Beekeepers supplying pollination services to the Western Cape deciduous fruit industry were interviewed to obtain information on their use of floral resources. For 120 apiary sites, we also analysed floral resources within a two km radius of each site based on geographic data. The relative availability of floral resources at sites was compared to regional availability. The relative contribution of floral resources-types to sustain managed honeybees was estimated. Beekeeper...
Although South African cycads are known to be declining in the wild, there is at present no broad... more Although South African cycads are known to be declining in the wild, there is at present no broad-scale, quantitative analysis to support this view. In this study the fate of 626 individual cycads was assessed from 107 repeat photographs taken at 53 locations over three time-steps (broadly 1940s, mid-1990s and 2014). Of the cycads photographed in the 1940s, 78 % survived to the mid-1990s. By 2014, however, only 16 % of the original cycads remained. The Limpopo Province had the highest rate of cycad loss over the recorded period, followed by the Eastern Cape and KwaZulu-Natal. Gauteng and Mpumalanga had the lowest rate of cycad loss. In general, cycad losses were greatest on land under private ownership when compared to communal land and conservation areas. However, cycad loss as a result of damage sustained due to traditional medicine collection was highest on communal lands. Continued declines in most of the studied cycad populations are a concern due to the potential Allee effects this may introduce. While legislation to protect cycads is in place, enforcement is difficult given the spatially extensive and often remote and patchy distribution of cycad populations. Conservation approaches that work actively with farmers to protect cycads on their property, as well as education about sustainable traditional medicine collection practices in communal areas have the best chance of ensuring the viability of wild cycad populations.
Proceedings. Biological sciences / The Royal Society, Jan 7, 2015
Brood-site mutualisms represent extreme levels of reciprocal specialization between plants and in... more Brood-site mutualisms represent extreme levels of reciprocal specialization between plants and insect pollinators, raising questions about whether these mutualisms are mediated by volatile signals and whether these signals and insect responses to them covary geographically in a manner expected from coevolution. Cycads are an ancient plant lineage in which almost all extant species are pollinated through brood-site mutualisms with insects. We investigated whether volatile emissions and insect olfactory responses are matched across the distribution range of the African cycad Encephalartos villosus. This cycad species is pollinated by the same beetle species across its distribution, but cone volatile emissions are dominated by alkenes in northern populations, and by monoterpenes and a pyrazine compound in southern populations. In reciprocal choice experiments, insects chose the scent of cones from the local region over that of cones from the other region. Antennae of beetles from north...
Abstract. 1 Second instar Filippia gemina de Lotto scale insects are the preferred hosts of femal... more Abstract. 1 Second instar Filippia gemina de Lotto scale insects are the preferred hosts of female Coccophugus atrutus Compere larvae. These scale insects were found on their host plants, Chrysanthemoides monilifera Norlindh and Cliffortia strobilifera Mettenius, only at certain times during a 1 year sampling programme. 2 Late larval instars and prepupae of C.atratus, and a Metaphycus species, are the preferred hosts of male C.atratus larvae. These hosts, although they occurred on the same host plants as hosts for female C.atratus, were most numerous at different times during the sampling period. 3 The ratio of hosts suitable for C.atratus varied from a predominance of hosts suitable for females through to a predominance of hosts suitable for males. Sex ratios of adult C.atratus followed a similar trend but did not reflect, exactly, the ratio of available hosts. Differences in mortality between sexes and hyperparasitism may account for this anomaly. 4 Variable population sex ratios observed in C.atratus apparently result from the behaviour of individual females in which brood sex ratios are dependent on the relative availability of hosts for males and hosts for females. This behaviour, in turn, may result from variability in the host population structure but may also result from selection pressures operating at the time that heteronomous hyperparasitism evolved.
Cape porcupines (Hystrix africaeaustralis) appear to have an important influence on landscapes th... more Cape porcupines (Hystrix africaeaustralis) appear to have an important influence on landscapes through both biotic (foraging) and abiotic (soil turnover) impacts. Porcupine abundance and abiotic effects across the landscape were investigated in Nieuwoudtville, ...
<b>Supporting Raw Data</b> This excel contains supporting raw data for the manuscript... more <b>Supporting Raw Data</b> This excel contains supporting raw data for the manuscript, including: Sequence ID, collector information, date of pollen collection, Location of apiary, source of pollen<br> <b>DNA Data</b> This file contains the DNA sequence data to support the manuscript. The key for the pollen samples, including apiary location is contained in the raw data excel spreadsheet.From: Annalie Melin, Jonathan F Colville, Gregory D Duckworth, Res Altwegg, Ruhan Slabbert, Jeremy J Midgley, Mathieu Rouget &amp; John S Donaldson (2020) Diversity of pollen sources used by managed honey bees in variegated landscapes, Journal of Apicultural Research, DOI: 10.1080/00218839.2020.1750757<br>
Brood-site mutualisms represent extreme levels of reciprocal specialization between plants and in... more Brood-site mutualisms represent extreme levels of reciprocal specialization between plants and insect pollinators, raising questions about whether these mutualisms are mediated by volatile signals and whether these signals and insect responses to them covary geographically in a manner expected from coevolution. Cycads are an ancient plant lineage in which almost all extant species are pollinated through brood-site mutualisms with insects. We investigated whether volatile emissions and insect olfactory responses are matched across the distribution range of the African cycad Encephalartos villosus. This cycad species is pollinated by the same beetle species across its distribution, but cone volatile emissions are dominated by alkenes in northern populations, and by monoterpenes and a pyrazine compound in southern populations. In reciprocal choice experiments, insects chose the scent of cones from the local region over that of cones from the other region. Antennae of beetles from northern populations responded mainly to alkenes, while those of beetles from southern populations responded mainly to pyrazine. In bioassay experiments, beetles were most strongly attracted to alkenes in northern populations and to the pyrazine compound in southern populations. Geographical matching of cone volatiles and pollinator olfactory preference is consistent with coevolution in this specialized mutualism
Most pollination ecosystem services studies have focussed on wild pollinators and their dependenc... more Most pollination ecosystem services studies have focussed on wild pollinators and their dependence on natural floral resources adjacent to crop fields. However, managed pollinators depend on a mixture of floral resources that are spatially separated from the crop field. Here, we consider the supporting role these resources play as an ecosystem services provider to quantify the use and availability of floral resources, and to estimate their relative contribution to support pollination services of managed honeybees. Beekeepers supplying pollination services to the Western Cape deciduous fruit industry were interviewed to obtain information on their use of floral resources. For 120 apiary sites, we also analysed floral resources within a two km radius of each site based on geographic data. The relative availability of floral resources at sites was compared to regional availability. The relative contribution of floral resources-types to sustain managed honeybees was estimated. Beekeeper...
Although South African cycads are known to be declining in the wild, there is at present no broad... more Although South African cycads are known to be declining in the wild, there is at present no broad-scale, quantitative analysis to support this view. In this study the fate of 626 individual cycads was assessed from 107 repeat photographs taken at 53 locations over three time-steps (broadly 1940s, mid-1990s and 2014). Of the cycads photographed in the 1940s, 78 % survived to the mid-1990s. By 2014, however, only 16 % of the original cycads remained. The Limpopo Province had the highest rate of cycad loss over the recorded period, followed by the Eastern Cape and KwaZulu-Natal. Gauteng and Mpumalanga had the lowest rate of cycad loss. In general, cycad losses were greatest on land under private ownership when compared to communal land and conservation areas. However, cycad loss as a result of damage sustained due to traditional medicine collection was highest on communal lands. Continued declines in most of the studied cycad populations are a concern due to the potential Allee effects this may introduce. While legislation to protect cycads is in place, enforcement is difficult given the spatially extensive and often remote and patchy distribution of cycad populations. Conservation approaches that work actively with farmers to protect cycads on their property, as well as education about sustainable traditional medicine collection practices in communal areas have the best chance of ensuring the viability of wild cycad populations.
Proceedings. Biological sciences / The Royal Society, Jan 7, 2015
Brood-site mutualisms represent extreme levels of reciprocal specialization between plants and in... more Brood-site mutualisms represent extreme levels of reciprocal specialization between plants and insect pollinators, raising questions about whether these mutualisms are mediated by volatile signals and whether these signals and insect responses to them covary geographically in a manner expected from coevolution. Cycads are an ancient plant lineage in which almost all extant species are pollinated through brood-site mutualisms with insects. We investigated whether volatile emissions and insect olfactory responses are matched across the distribution range of the African cycad Encephalartos villosus. This cycad species is pollinated by the same beetle species across its distribution, but cone volatile emissions are dominated by alkenes in northern populations, and by monoterpenes and a pyrazine compound in southern populations. In reciprocal choice experiments, insects chose the scent of cones from the local region over that of cones from the other region. Antennae of beetles from north...
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