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... active principle behind this could be alkaloid or saponins, but to prove this, more study has to be conducted. In a study conducted by [49] to identify insecticidal plants of potential value in Sri Lanka, C. aurantiacum rec- orded very high mortality [101] (See Table 3). Also C. aurantiacum showed stronger antibacterial activity compared to other species and acetone extract of C. aurantiacum produced maximum zone of inhibition (18 mm) against K. ...
Context 2
... beneficial uses of cestrum species have also been documented (see Ta- ble 3). The flowers of Cestrum aurantiacum are visited by the bees in the ab- sence of coffee flowers in Kiambu Kenya [108]. ...
Context 3
... planting of some Cestrum species is still promoted in some parts of Kenya (See Table 3). This is against background understanding that People with respiratory sensitivities or asthma, have reported difficulty in breathing, irrita- tion of the nose and throat, headache, nausea, or other symptoms when exposed to the blossom's powerful scent [127]. ...
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Citations
... These invasive species, often foreign to a particular ecosystem, wreak havoc on native flora and fauna (Chepkoech et al. 2018). This destructive relationship between climate change and invasive species has been noted as a significant driver of ecological shifts (Makokha, 2018). ...
Occurrence of severe drought in northeastern Kenya has emerged as a critical threat to the giraffe population in the region, exacerbating a multitude of pre-existing challenges. The primary concern stems from the drying up of acacia trees, a crucial feed source for giraffes. As these trees wither due to the prolonged drought, the giraffes are confronted with a diminishing feed supply, leading to malnutrition and an alarming decline in their overall population. One immediate consequence of the drought is the migration of giraffes to neighboring countries such as Ethiopia and Somalia in search of sustenance. Unfortunately, the situation in these regions, particularly Somalia, has been aggravated by persistent civil unrest since 1991. The ongoing conflict not only exacerbates the challenges faced by giraffes but also poses additional threats to their survival. The violence and instability in these areas hinder conservation efforts, making it more difficult to implement protective measures and conservation programs. Beyond the drought and migration, giraffes in northeastern Kenya are grappling with a host of other issues. Habitat loss, primarily driven by human activities such as deforestation and land development, further diminishes the available living space for giraffes. The encroachment of agriculture, expanding settlements, and infrastructure development contribute to the shrinking of their natural habitats.
... The genus Cestrum is native to Central and South America where it thrives in montane forests (Monro, 2012). The abundant, attractive and fragrant flowers of this genus are the reason it has been introduced as an ornamental plant in many regions, where it has subsequently become naturalized, and in several cases, turned invasive, including in parts of Africa, Asia, Australia and multiple oceanic islands (Henderson, 2007;Harvey et al., 2012;Junaedi, 2012;Gardener et al., 2013;Padmanaba et al., 2017;Makokha, 2018). In the Indian subcontinent, C. aurantiacum has been reported across many montane regions including the Himalaya, the Western Ghats and in Sri Lanka (Kunwar, 2003;Sajeev et al., 2012;Wijesundara, 2012;Moktan and Das, 2013;Mandal and Joshi, 2015;Nayak et al., 2020). ...
... They are also shadetolerant (Geldenhuys, 2004), drought-tolerant, capable of growing on poor soils and have invaded a range of habitats from coastal dunes to savannahs, grasslands, plantations and closed forest (Henderson, 2007). Most are quite toxic to livestock, native mammals and humans (de Rojas and D'Arcy, 1998;Makokha, 2018). For these reasons, they are labelled as noxious weeds with moderate to high invasive potential (Nel et al., 2004;Henderson, 2007). ...
... It is native to central America (Costa Rica, Guatemala, Honduras, Mexico and Nicaragua; CABI, 2023). In many parts of its invaded range, C. aurantiacum occurs in montane forests, between 1500 to above 2000m (Junaedi, 2012;Sajeev et al., 2012;Wijesundara, 2012;Moktan and Das, 2013;Makokha, 2018;Witt et al., 2018). In the Nilgiris, it has successfully invaded native forest fragments and the understorey of tree plantations above 2000 m (Saravanan et al., 2014, Figure 1). ...
In the montane forest-grassland mosaics of the Western Ghats, land cover conversion to silviculture and agriculture over the last five decades has resulted in both loss of natural habitats and widespread invasion of remnant habitat patches. While invasion of the grassland habitats of the mosaic has been relatively well studied, there have been few attempts to understand the extent to which forest habitats (locally known as sholas) have been affected by the spread of exotic species. Here we examine the patterns and impacts of invasion of shola forest understoreys by Cestrum aurantiacum Lindl., an exotic shrub species. At the landscape scale, we demonstrate that the presence and abundance of this invasive in shola understories is negatively related to distance from tea plantations. Further, the intensity of invasion is higher in areas with greater seasonality of temperature and lower mean annual precipitation. At the patch scale, invasion is greatest at shola edges and away from stream courses. We find that C. aurantiacum abundance has negatively affected the regeneration of native shola tree species as well as the abundance of native shola understorey shrubs. Fifty three percent of invaded plots had no native shrubs present. In plots where both C. aurantiacum and native shrubs were present in large enough numbers, we found evidence of negative spatial dependence between stem locations of C. aurantiacum and native shrubs. Our findings have important implications for the management and conservation of these mosaics.
... Species like Ageratina spp., Ageratum spp., Cestrum aurantiacum, Lantana camara, and Pteridium aquilinum (henceforth, Ageratina complex, Cestrum, Lantana, and Pteridium, respectively) have invaded multiple locations across Shola Sky Islands (Balaguru et al., 2016;Das, 2015). These species are considered invasive globally (Bhatt et al., 2011;Cowie et al., 2018;Goncalves et al., 2014;Makokha, 2018;Marrs & Watt, 2006;Wan et al., 2010). Most interactions between the invasive overstory species and invasive understory species are thought to be neutral or negative (Kuebbing & Nuñez, 2015), but positive interactions are uncommon (Gómez-Aparicio, 2009). ...
Current climate and land cover change threaten global mountaintops with increased spread of invasive species. Long-established plantations of invasive trees on these mountaintops can alter their surroundings, further increasing invader-facilitated invasion. Identifying the ecological conditions promoting such associations can help develop better management interventions. The Western Ghats's Shola Sky Islands (>1400 m MSL) host vast stretches of invasive tree plantations that sustain the colonization of other invasive woody, herbaceous, and fern species in their understories. Here, we analyzed vegetation and landscape variables from 232 systematically placed plots in randomly selected grids using non-metric multidimensional scaling and Phi coefficient approaches to examine patterns of association (positive interactions) between understory invasive species with specific invasive overstory species. We also conducted GLMM with zero inflation to determine the influence of environmental variables where such associations occur. We find that understory invasion of multiple species under the canopy of other invasives is widespread across the Shola Sky Islands. Stands of Eucalyptus host the colonization of 70% of non-native invasive species surveyed across the Shola Sky Islands. In particular, the Lantana camara invasion is strongly associated with Eucalyptus stands. We also found that climatic variables affect the colonization of understory woody invasive species, while invasion by exotic herbaceous species is associated with the density of road networks. Canopy cover impacts all invasives negatively, while fire incidence was negatively associated with invasion by Lantana spp. and the Pteridium spp. While the restoration of natural habitats primarily targets the highly invasive Acacia, less invasive Eucalyptus and Pinus are often not included. Our study suggests that retaining such invasive species in natural habitats, particularly protected areas, can hinder ongoing grassland restoration efforts by facilitating further invasions by multiple woody and herbaceous species.
... Cestrum aurantiacum, commonly known as orange jessamine, is isolated at a few sites near Pietermaritzburg in KZN Province. However, it is reported to have invasive tendencies in eSwatini, Zimbabwe and Kenya (Shone & Drumond 1965;Fourie 2011;Makokha 2018;Anon. 2019). ...
Cestrum (Solanaceae) species have become invasive in conservation and agricultural areas in South Africa, resulting in the initiation of a biological control (biocontrol) programme against these species in 2007. Of the four Cestrum species recorded in South Africa, Cestrum laevigatum Schltdl. and C. parqui L'Herit., which are both commonly referred to as inkberries, have become invasive while C. aurantiacum Lindl. and C. elegans (Brongn.) Schltdl. are still isolated at a few sites in the country. The biocontrol programme against Cestrum species (commonly called cestrum) was initially focussed on pathogens associated with these plants. Although the fungus Uromyces cestri Bertero ex Mont. (Pucciniales: Pucciniaceae) was found to be a promising agent for cestrum, the pathogen project was shelved due to lack of capacity. Field surveys conducted in Argentina from 2012 to 2020 revealed a total of eight phytophagous insects that could be candidate agents. Among these is a leaf-feeding flea beetle Epitrix sp. (Coleoptera: Chrysomelidae) that has been tested for host specificity. Out of 47 plant species tested to date, Epitrix sp. has only fed and developed on three Cestrum species, suggesting that it is suitable for release against cestrum in South Africa. Permission to release Epitrix sp. will be sought once it has been identified to the species level or it has been described as a new species. Two chrysomelid beetle species, a root-feeding flea beetle (Diphaulaca sp.) and an unidentified leaf-feeding flea beetle, were also collected on C. parqui, but attempts to rear the former were unsuccessful. Three other leaf-miners collected from C. parqui include: Acrocercops leucographa Clark (Lepidoptera: Gracillariidae), an unidentified moth (Lepidoptera: Argyresthiidae) and Liriomyza sp. nr. schlingerii (Diptera: Agromyzidae). A glass-winged butterfly (Lepidoptera: Nymphalidae) was the only herbivore that may be of biocontrol value on C. laevigatum. Whilst it is essential to extend the surveys to other regions of the native range, it is also important to prioritize the most promising potential biocontrol agents for further testing in South Africa. Given the suite of potential biocontrol agents in the native range, there are good prospects for the biocontrol of cestrum species in South Africa.
Current climate and land cover change threaten global mountaintops with the increased spread of invasive species. Long-established plantations of exotic and invasive trees on these mountaintops can alter their surroundings, further increasing invader-facilitated or secondary invasion. Identifying the ecological conditions that promote such specific associations can help develop better management interventions.
The Western Ghats's Shola Sky Islands (>1400m MSL) host vast stretches of exotic and invasive tree plantations that sustain the colonisation of other invasive woody, herbaceous and fern species in their understories. Here we analysed vegetation and landscape variables from 232 systematically-placed plots in randomly selected grids using NMDS and Phi Coefficient approaches to examine patterns of association (positive interactions) between secondary understory invasive species with specific exotic and invasive overstory species. We also conducted GLMM with zero inflation to determine the influence of environmental variables where such associations occur.
We find that secondary invasion of multiple species under the canopy of other exotic invasives is widespread across the Shola Sky Islands. Stands of Eucalyptus host the colonisation of 70% of non-native invasive species surveyed across the Shola Sky Islands. In particular, the Lantana camara invasion is strongly associated with Eucalyptus stands.
We also found that climatic variables affect the colonisation of understorey woody invasive species, while invasion by exotic herbaceous species is associated with the density of road networks. Canopy cover impacts all invasives negatively, while fire incidence was negatively associated with invasion by Lantana spp and the Pteridium spp. While the restoration of natural habitats largely targets the highly invasive Acacia, less invasive Eucalyptus and Pine are often not included. Our study suggests that retaining such exotic species in natural habitats, particularly protected areas, can hinder ongoing restoration efforts by facilitating further invasions by multiple woody and herbaceous species.
