Ingestion by an invasive parakeet species reduces germination success of invasive alien plants relative to ingestion by indigenous turaco species in South Africa

Avian frugivores play a key role in seed dispersal of many plant species, including invasive alien plants. We assessed the effect of gut passage on the germination of selected invasive alien plant species in South Africa. Fruits of four fleshly-fruited invasive alien plant species: Solanum mauritianum, Cinnamomum camphora, Psidium guajava, and Morus alba, were fed to two species of indigenous turacos, Knysna (Tauraco corythaix) and purple-crested (Gallirex porphyreolophus) turacos, and to invasive roseringed parakeets (Psittacula krameri). Seed retention time was determined as this can influence both seed dispersal and germination success. Germination success of ingested seeds was compared with that of manually de-pulped seeds, as well as to seeds in whole fruit. The germination success of seeds of all the invasive plant species increased significantly after ingestion by both turaco species compared with seeds from whole fruits. Germination success of manually de-pulped seeds did not differ significantly from that of turaco ingested seeds. In contrast, seed passage through the digestive tract of rose-ringed parakeets significantly reduced germination success and viability of ingested invasive plant species. Our results suggest that Knysna and purple-crested turacos are legitimate seed dispersers of fleshy-fruited invasive plants, while rose-ringed parakeets are mainly seed predators. Although seed predation by rose-ringed parakeets negatively affects the reproductive success of these plants, it is unlikely that this will suppress the spread of these invasive alien plants in South Africa as they are already well established. Furthermore, they can facilitate dispersal by seed regurgitation and dropping uneaten fruits away from the parent plant. Similar trends could be expected for indigenous seeds that rose-ringed parakeets feed on and therefore these birds remain a negative influence within invaded ecosystems

Ingestion by an invasive parakeet species reduces germination success of invasive alien plants relative to ingestion by indigenous turaco species in South Africa

Avian frugivores play a key role in seed dispersal of many plant species, including invasive alien plants. We assessed the effect of gut passage on the germination of selected invasive alien plant species in South Africa. Fruits of four fleshly-fruited invasive alien plant species: Solanum mauritianum, Cinnamomum camphora, Psidium guajava, and Morus alba, were fed to two species of indigenous turacos, Knysna (Tauraco corythaix) and purple-crested (Gallirex porphyreolophus) turacos, and to invasive roseringed parakeets (Psittacula krameri). Seed retention time was determined as this can influence both seed dispersal and germination success. Germination success of ingested seeds was compared with that of manually de-pulped seeds, as well as to seeds in whole fruit. The germination success of seeds of all the invasive plant species increased significantly after ingestion by both turaco species compared with seeds from whole fruits. Germination success of manually de-pulped seeds did not differ significantly from that of turaco ingested seeds. In contrast, seed passage through the digestive tract of rose-ringed parakeets significantly reduced germination success and viability of ingested invasive plant species. Our results suggest that Knysna and purple-crested turacos are legitimate seed dispersers of fleshy-fruited invasive plants, while rose-ringed parakeets are mainly seed predators. Although seed predation by rose-ringed parakeets negatively affects the reproductive success of these plants, it is unlikely that this will suppress the spread of these invasive alien plants in South Africa as they are already well established. Furthermore, they can facilitate dispersal by seed regurgitation and dropping uneaten fruits away from the parent plant. Similar trends could be expected for indigenous seeds that rose-ringed parakeets feed on and therefore these birds remain a negative influence within invaded ecosystems

Comparing germination metrics of Opuntia ficus-indica and O. robusta between two sets of bird species (Pied Crows and two smaller species)

The fleshy fruits of exotic Opuntia ficus-indica (L.) Mill and Opuntia robusta (Haw.) Haw (Cactaceae family) are consumed and dispersed by many vertebrates, which likely influences their invasion success. We tested whether seed ingestion by Pied Crows (Corvus albus) and other smaller birds (African Pied Starling Lamprotornis bicolor and the Red-eyed Bulbul Pycnonotus nigricans) improve the germination and speed in O. ficus-indica and O. robusta. Controlled germination trials for two Opuntia species were set up using the seeds extracted from faecal material, depulped seeds, and intact fruits. Overall, results show that seed germination for O. robusta was significantly higher than for O. ficus-indica. There were significant differences in seed germination between treatments of two Opuntia species, with the total mean germination of seeds defecated by the Pied Crows being equivalent to that of seeds defecated by the other smaller birds but significantly greater than the other treatments (i.e., depulped seeds and intact fruit). We noted that removal of the fruit pulp from seeds significantly improved germination in both Opuntia species compared to intact fruits. The O. robusta seeds defecated by the smaller birds had significantly greatest and most accelerated germination of all other treatments followed by the seeds defecated by the Pied Crows. Seeds of O. ficus-indica defecated by the Pied Crows had significantly greater germination than the seeds ingested by smaller birds. We conclude that seed germination success in fleshy fruits including those of alien species, varies with seed treatment by different vertebrate dispersal agents, and their net effect on seeds, may have consequences on species invasion success

Digestive efficiency of indigenous and invasive avian species fed fruit of invasive alien plants in South Africa

Many highly invasive plant species produce fleshy fruit that are consumed and dispersed by frugivorous birds. However, little is known about assimilation efficiency of invasive fruit by indigenous and invasive avian species. We investigated whether indigenous Knysna (Tauraco corythaix) and Purple-crested (Gallirex porphyreolophus) Turacos and invasive alien Rose-ringed Parakeets (Psittacula krameri) met their energy demands when fed fruits of four fleshy-fruited invasive alien plant species: Solanum mauritianum, Cinnamomum camphora, Psidium guajava and Morus alba. Birds were fed single-fruit diets for two consecutive days and energetic parameters were calculated for all fruit diets. Our results showed that generally both invasive and indigenous avian species managed to gain their daily energy requirements from fruits of the four respective invasive plants, suggesting that they can meet their energetic demands by feeding on them only. The exception was P. krameri, which did not feed on S. mauritianum fruit. These findings may explain why fruits of invasive alien plants are attractive to most avian frugivores and highlight the role of avian frugivores in their dispersal

Digestive efficiency of indigenous and invasive avian species fed fruit of invasive alien plants in South Africa

Many highly invasive plant species produce fleshy fruit that are consumed and dispersed by frugivorous birds. However, little is known about assimilation efficiency of invasive fruit by indigenous and invasive avian species. We investigated whether indigenous Knysna (Tauraco corythaix) and Purple-crested (Gallirex porphyreolophus) Turacos and invasive alien Rose-ringed Parakeets (Psittacula krameri) met their energy demands when fed fruits of four fleshy-fruited invasive alien plant species: Solanum mauritianum, Cinnamomum camphora, Psidium guajava and Morus alba. Birds were fed single-fruit diets for two consecutive days and energetic parameters were calculated for all fruit diets. Our results showed that generally both invasive and indigenous avian species managed to gain their daily energy requirements from fruits of the four respective invasive plants, suggesting that they can meet their energetic demands by feeding on them only. The exception was P. krameri, which did not feed on S. mauritianum fruit. These findings may explain why fruits of invasive alien plants are attractive to most avian frugivores and highlight the role of avian frugivores in their dispersal

Growth performance of South African Windsnyer pigs to the dietary inclusion of Amarula oil cake

Dietary inclusion of Amarula oil cake (AOC) in pig diets can ease pressure of relying on non-native feed sources and beneft the swine industry. The study was conducted to determine the growth performance of Windsnyer pigs fed increasing levels of AOC. Twenty-fve clinically growing male boars with an initial body weight of 19.92±8.74 kg were used in the study that lasted 6 weeks. All pigs were allocated to diets in a completely randomised design. Five experimental diets were formulated to contain 0, 50, 100, 150 and 200 g/kg DM of AOC. Average daily feed intake (ADFI), average daily gain (ADG), feed conversion ratio (FCR), scaled average daily feed intake (SADFI), scaled average daily gain (SADG) and body weight (BW) were calculated weekly. The diet afected ADFI, ADG, FCR and SADG (P<0.05). Scaled average daily feed intake was not afected by the diet (P>0.05). There was a signifcant interaction between AOC inclusion and weeks of feeding on ADFI, ADG and FCR (P<0.05). Age of pigs decreased FCR quadratically (P<0.001). A quadratic relationship between ADFI and increasing levels of AOC was observed (P<0.05). Average daily gain, FCR and SADG decreased linearly with increasing AOC levels (P<0.05). Using the broken stick analyses, the maximum inclusion of AOC was 102.17 g/kg DM. Amarula oil cake can be incorporated in diets of Windsnyer pigs up to 100 g/kg DM without constraining growth performance.info:eu-repo/semantics/publishedVersio

Role of native avian frugivores in germination facilitation and potential dispersal of invasive American bramble (Rubus cuneifolius) in South Africa

Frugivorous birds are important in the dispersal of many fleshy-fruited plant species, including invasive plants. Consequently, we investigated three native frugivorous avian species’ role in potential dispersal and germination success of the invasive American bramble (Rubus cuneifolius) in South Africa, particularly in terms of amount of fruit ingested, transit time, and their effects on seed germination. Three common species of frugivorous bird species were predicted to positively affect the spread of invasive R. cuneifolius. The bird species (speckled mousebirds Colius striatus, red-winged starlings Onychognathus morio and dark-capped bulbuls Pycnonotus tricolor) were fed R. cuneifolius fruit in captivity and amounts ingested were determined together with transit times. Seeds that were excreted and/or regurgitated by the three bird species, manually extracted seeds, and control whole fruit were then planted and their germination assessed daily. Although the three bird species varied in the amount of fruit consumed (~ 10–30 g), there was no significant difference in amount of R. cuneifolius fruit eaten per gram body mass among the species. Bird-ingested seeds emerged a mean 21–23 days after planting, while the seeds from the whole fruit took longer to emerge (mean 28 days). Germination of seeds ingested by the respective bird species was significantly higher (~ 60–75%) than seeds manually removed from fruits (~ 52%) or seeds in whole fruits (~ 7%). This suggests that removal of pulp and seed coat abrasion by the birds increased germination success. The three bird species all had R. cuneifolius seed transit times greater than 20 min, demonstrating their potential to disperse seeds a distance away from the parent plant. The results showed that the three bird species increased the germination success and suggests they are potentially important dispersers of the invasive R. cuneifolius

Modeling and X-ray Analysis of Defect Nanoclusters Formation in B4C under Ion Irradiation

In the presented work, B4C was irradiated with xenon swift heavy ions at the energy of 167 MeV. The irradiation of the substrate was done at room temperature to a fluence of 3.83 &times; 1014 ion/cm2. The samples were then analyzed with the X-ray diffraction technique to study the structural modification, as it can probe the region of penetration of xenon atoms due to the low atomic number of the two elements involved in the material under study. The nano-cluster formation under ion irradiation was observed. Positron lifetime (PLT) calculations of the secondary point defects forming nanoclusters and introduced into the B4C substrate by hydrogen and helium implantation were also carried out with the Multigrid instead of the K-spAce (MIKA) simulation package. The X-ray diffraction results confirmed that the sample was B4C and it had a rhombohedral crystal structure. The X-ray diffraction indicated an increase in the lattice parameter due to the Swift heavy ion (SHI) irradiation. In B12-CCC, the difference between &tau; with the saturation of H or He in the defect is nearly 20 ps. Under the same conditions with B11C-CBC, there is approximately twice the value for the same deviation