The role of cone volatiles and thermogenesis in the pollination of Encephalartos cycads with particular reference to E.villosus

Includes abstract.Includes bibliographical references.Pollination systems of cycads usually involve obligate mutualisms in which the cycad taxa depend on between one and three insect pollinators. Generally, the pollination periods of many cycad taxa are characterised by odour emissions in pollen shedding (male) and receptive (female) cones usually accompanied by heat production. The emission of cone odours and heat production coincide with periods of insect activity on the cones..

Scent chemistry and patterns of thermogenesis in male and female cones of the African cycad Encephalartos natalensis (Zamiaceae)

Most, if not all, extant cycads are pollinated by insects which use the cones as larval brood sites. These interactions appear to be mediated by cone volatiles, and, in some species, by patterns of thermogenesis. We investigated the chemical composition of volatile emissions and patterns of thermogenesis in cones of the South African cycad Encephalartos natalensis, using a gas chromatograph–mass spectrometer (GC–MS) and miniature temperature data loggers (ibuttons), respectively. This was done during various developmental stages (before and during receptivity and pollen release) for both female and male cones. A total of 31 compounds were identified in headspace samples; 17 of which were common to both sexes, 12 found only in male cones, and two found only in female cones. The major volatiles in pollen and female cones are (3E)-1,3-octadiene (averaging 54.25% and 15.82% of total emissions), (3E,5Z)-1,3,5-octatriene (averaging 13.37% and 47.66%), and α-pinene (averaging 16.29% and 12.24%). Female cones were not thermogenic before and during receptivity whereas pollen cones were thermogenic during pollen shedding. Thermogenesis of male cones occurred between 1400 h and 1530 h on successive afternoons, reaching an average of c. 10.5 °C above ambient temperature. Volatile emissions and thermogenesis occurred in association with insect activity on the cones suggesting that they both play a role in regulating insect behaviour

Physicochemical properties and antioxidant activities of marula fruit (Sclerocarya birrea subsp. Caffra) steamed and boiled before juice extraction

DATA AVAILABILITY STATEMENT : The data that support the findings of this study are available on request from the corresponding author.Marula fruit is one of the most underutilized fruits in South Africa, and it has been reported to contain a high amount of vitamin C which is regarded as the cheapest antioxidant. The fruit pulp is traditionally extracted and boiled into juice, a process that adversely affects the vitamin C and bioactive phenolic profile of the resulting juice. This study evaluated the effects of boiling and steaming on the physicochemical properties of marula fruit juice. The pH, percentage yield, total titratable acidity (TTA), total soluble solids (TSS), total phenolic content (TPC), radical scavenging capacity, and vitamin C content of the fruit juice were examined. The study also investigated the total carotene, color, and sensory properties of the fruit juice. The results showed that boiling and steaming significantly decreased the Vit C content of the juice (75.67 and 60.05 mg/100 g) compared to control sample (95.11 mg/100 g). The TPC, radical scavenging capacity, and total carotene content of the fruit juice increase because the heating processes softened the matrix of the fruit increasing the extractability of the phenolics and carotene content of the samples. The color of the marula fruit juice was increased by both boiling and steaming, while the sensory properties of the marula fruit juice extracted from steamed marula fruit had the highest scores in all the measured parameters. Steaming of marula fruit before juice extraction improved the nutritional composition, antioxidant activities, and sensory properties of marula fruit juice.http://wileyonlinelibrary.com/journal/fsn3am2024Consumer ScienceSDG-02:Zero Hunge

Short NoteCattle Egret and Common Ostrich associations in South Africa

No AbstractOstrich 2008, 79(1): 105–10

Data from: Geographical matching of volatile signals and pollinator olfactory responses in a cycad brood-site mutualism

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