First report of the ambrosia beetle, <i>Amasa parviseta</i> (Curculiondae: Scolytinae), in South Africa

A recent global assessment of terrestrial alien true ferns (Polypodiophyta; hereafter alien ferns) showed that alien ferns have a high probability of becoming naturalised or invasive once introduced. We provide the first systematic assessment, based on field surveys, of the invasion status of this large taxon in South Africa. Thirteen species of alien ferns were recorded outside of cultivation and subsequently identified as invasive in South Africa. Surveys were focused in known hotspots of alien and native ferns, with invasion density peaking along the eastern coastal belt of South Africa. Within the surveyed areas, alien ferns commonly occurred with other invaders, closer to water and often in indigenous forests. The species considered in this study generally occurred in similar habitat types across their native and globally introduced ranges (including South Africa). The potential spread of alien ferns in South Africa appears limited when compared to other major invaders, however, their common occurrence in indigenous forests highlights a concern for native, co-habiting fern species (in terms of competition). Our study provided regulatory insight for 12 previously unregulated alien fern species in South Africa. We propose that eradication remains feasible for Diplazium esculentum, Doodia caudata, Lygodium japonicum, Phlebodium aureum and Platycerium bifurcatum. A risk analysis for Sphaeropteris cooperi classified the species as high risk and comprised the first quantification of risk for any alien fern species (inclusive of aquatics) in South Africa. The information put forward in this study can be used to inform risk analyses for the remaining species in South Africa, as well as countries with similar habitats and climates. Furthermore, widely traded species need to be identified as candidates for future risk assessment since horticulture is an important introduction pathway for alien ferns globally.

BackgroundMangrove forests are of fundamental significance that support a diverse array of species, but despite their importance and the benefits they provide, the health of these trees is under constant threat. This is due to a variety of environmental and human factors, which lead to their weakening and susceptibility to colonization by insect pests. Although the diversity of bark and ambrosia beetles has been well documented worldwide, there is limited information available regarding their relationships with mangroves. To investigate the diversity and distribution of ambrosia and bark beetles associated with mangrove habitats in South Africa, extensive field surveys and species sampling across various mangrove sites were carried out, as well as Lindgren and Panel traps were installed along five estuaries in KwaZulu–Natal and one in the Eastern Cape Province, from October to December 2013 and January to February 2014.ResultsA total of 8677 individuals comprising 11 genera and 16 species of ambrosia and bark beetles were captured. Of these, the most abundant was Hypothenemus eruditus (n = 2178; 25.10%), followed by Ambrosiodmus natalensis (n = 863; 10.36%), Xyleborus affinis (n = 844; 9,73%) and Premnobius cavipennis (n = 833; 9,60%), respectively. The remaining species registered an incidence lower than 7%. From the analysis of representativeness by rarefaction curves, there was no trend toward an increase in species as the number of trajectories increased.ConclusionsThis research contributes to understanding the biodiversity of ambrosia and bark beetle assemblages within South African mangrove ecosystems and underscores the importance of conserving these habitats in the face of environmental and anthropogenic pressures. The findings provide a valuable baseline for future studies and management strategies aimed at preserving mangrove health and monitoring beetle community dynamics in these critical coastal environments.

Holocryphia eucalypti is a fungal pathogen that causes stem cankers on Eucalyptus species in South Africa and Australia. In South Africa it is considered opportunistic but in Australia it has been associated with occasional but serious disease problems. The aim of this study was to determine the genetic structure of a South African population of H. eucalypti and compare it with three Australian populations of the fungus. Seventy-two isolates from Eucalyptus spp. and clones in South Africa were compared with 30 isolates from E. globulus and 24 isolates from Corymbia calophylla in the south of Western Australia and 23 isolates from E. dunnii in eastern Australia. DNA of these isolates was amplified using eight pairs of microsatellite markers previously developed for H. eucalypti. Nei's gene diversity (H) showed that the eastern Australian population is the most genetically diverse and the Western Australian populations from Corymbia and Eucalyptus are somewhat less diverse. The South African population displayed the lowest genetic diversity. The high genetic diversity in the Australian populations supports the view that H. eucalypti is native to that region and was introduced into South Africa.

From an economic point of view, agriculture and tourism, along with mining production, are South Africa’s largest economic sectors. However, South Africa is becoming increasingly reliant on ecotourism as an economic growth sector, which is, in turn, reliant on maintaining the productive and aesthetic value of South Africa’s protected areas and interstitial landscapes. This, together with other important human bene¢ts gained from maintaining biodiversity (e.g., ecological services, harvesting of wild species, aesthetically and culturally), suggests that key role players responsible for policy making in the country are faced with particular challenges where conservation and economic development needs are in con®ict (see e.g., reference1). Yet, at the same time, vertebrate introductions that result in invasions have the potential to alter these valuable environments. For example, considering the anthropogenic movement of ungulate species (both alien and extralimital) in South Africa, known for their recreation and food source value, Spear and Chown2 have shown that their movement has led to a 1.34% increase in the similarity of ungulate assemblages at a quarter-degree grid-cell resolution. At least 21 invasive ¢sh species are present in South Africa. While the impact of these species on aquatic ecosystems has been profound, resulting in the extirpation or localized extinction of a number of indigenous ¢shes, amphibians, and invertebrates, alien invasive ¢shes drive a large recreational ¢shery that has signi¢cant economic value. As a result of these positive economic contributions of certain invasive vertebrates, the implementation of legislation governing the importation and movement of both alien and extralimital species in South Africa will require careful consideration of the trade-offs between economic gain and biodiversity loss.

Understanding the status and extent of spread of alien plants is crucial for effective management. We explore this issue using Australian Acacia species (wattles) in South Africa (a global hotspot for wattle introductions and tree invasions). The last detailed inventory of wattles in South Africa was based on data collated forty years ago. This paper aimed to determine: 1) how many Australian Acacia species have been introduced to South Africa; 2) which species are still present; and 3) the status of naturalised taxa that might be viable targets for eradication. All herbaria in South Africa with specimens of introduced Australian Acacia species were visited and locality records were compared with records from literature sources, various databases, and expert knowledge. For taxa not already known to be widespread invaders, field surveys were conducted to determine whether plants are still present, and detailed surveys were undertaken of all naturalised populations. To confirm the putative identities of the naturalised taxa, we also sequenced one nuclear and one chloroplast gene. We found evidence that 141 Australian Acacia species have been introduced to South Africa (approximately double the estimate from previous work), but we could only confirm the current presence of 33 species. Fifteen wattle species are invasive (13 are in category E and two in category D2 in the Unified Framework for Biological Invasions); five have naturalised (C3); and 13 are present but there was no evidence that they had produced reproductive offspring (B2 or C1). DNA barcoding provided strong support for only 23 taxa (including two species not previously recorded from South Africa), the current name ascribed was not supported for three species and, for a further three species, there was no voucher specimen on GenBank against which their identity could be checked. Given the omissions and errors found during this systematic re-evaluation of historical records, it is clear that analyses of the type conducted here are crucial if the status of even well-studied groups of alien taxa is to be accurately determined.

Bark beetles (Coleoptera: Scolytinae) are well-recognized vectors of Ophiostoma species. Three non-native bark beetle species infest various Pinus species in South Africa, and they are known to carry at least 12 different species of ophiostomatoid fungi. Some of these fungi have not been identified to species level. The aim of this study was to determine or confirm the identities of Ophiostoma species associated with bark beetles in South Africa using comparisons of DNA sequence data. Identities of Ophiostoma ips, O. floccosum, O. pluriannulatum, O. quercus and O. stenoceras were confirmed. Ophiostoma abietinum, O. piliferum and Pesotum fragrans are recognised for the first time and the new species, O. aurorae sp. nov., is described from pine-infesting bark beetles in South Africa.

Diseases associated with ambrosia and bark beetles comprise some of the most significant problems that have emerged on trees in the last century. They are caused by fungi in the Ophiostomatales, Microascales, and Hypocreales, and have vectors in the Scolytinae (ambrosia and bark beetles) and Platypodinae (ambrosia beetles) subfamilies of the Curculionidae (Coleoptera). Some of these problems, such as Dutch elm disease, have a long history, have been extensively researched, and are fairly well understood. In contrast, other similar diseases developed recently and are poorly or partially understood. The emergence and unexpected importance of these tree diseases are discussed in this article. An underlying factor in most of these interactions is the absence of a coevolved history between the so-called "naïve" or "new encounter" host trees and the pathogens and/or beetles. For the ambrosia beetles, these interactions are associated with susceptibility to what are typically benign fungi and atypical relationships with healthy trees (ambrosia beetles favor trees that are dead or stressed). Interestingly, the pathogens for both the ambrosia and bark beetle-associated diseases often have symbiotic relationships with the insects that are not based on phytopathogenicity. Some of the most alarming and damaging of these diseases are considered "black swan events". Black swan developed as a metaphor for a supposed impossibility that is contradicted with new information. Today, Black Swan Theory focuses on unexpected events of large magnitude and consequence.

Cytospora spp. (anamorphs of Valsa spp.) are common inhabitants of woody plants and they include important stem and branch canker pathogens. Isolates of these fungi were collected from diseased and healthy trees in South Africa. They were identified based on morphology and DNA sequence homology of the intertransgenic spacer ribosomal DNA. South African isolates were compared with isolates collected in other parts of the world, and they represented 25 genetically distinct sequences residing within the populations of 13–14 known species and three unique lineages. Several species are new records for South Africa, doubling previous reports of these fungi from the country. Similarities between South African isolates of Cytospora from non-native Eucalyptus, Malus, Pinus, Populus, Prunus and Salix species and isolates from Australia, Europe or America suggest that the fungal pathogens were imported with their hosts as endophytes. Isolates from indigenous Olea and Acacia appear to represent native populations. Host shifts were evident, including populations on Eucalyptus that also occurred on Mangifera, Populus, Sequoia, Tibouchina and Vitex. Isolates related to Valsa kunzei represent the first report of a Cytospora species on the widely cultivated timber tree, Pinus radiata. An identification key to Cytospora species in South Africa is included.

Bark and ambrosia beetles are commonly moved among continents within timber and fresh wood-packaging materials. Routine visual inspections of imported commodities are often complemented with baited traps set up in natural areas surrounding entry points. Given that these activities can be expensive, trapping protocols that attract multiple species simultaneously are needed. Here we investigated whether trapping protocols commonly used to detect longhorn beetles (Coleoptera: Cerambycidae) and jewel beetles (Coleoptera: Buprestidae) can be exploited also for detecting bark and ambrosia beetles. In factorial experiments conducted in 2016 both in Italy (seminatural and reforested forests) and Canada (mixed forest) we tested the effect of trap color (green vs purple), trap height (understory vs canopy), and attractive blend (hardwood-blend developed for broadleaf-associated wood-boring beetles vs ethanol in Italy; hardwood-blend vs softwood-blend developed for conifer-associated wood-boring beetles, in Canada) separately on bark beetles and ambrosia beetles, as well as on individual bark and ambrosia beetle species. Trap color affected catch of ambrosia beetles more so than bark beetles, with purple traps generally more attractive than green traps. Trap height affected both beetle groups, with understory traps generally performing better than canopy traps. Hardwood-blend and ethanol performed almost equally in attracting ambrosia beetles in Italy, whereas hardwood-blend and softwood-blend were more attractive to broadleaf-associated species and conifer-associated species, respectively, in Canada. In general, we showed that trapping variables suitable for generic surveillance of longhorn and jewel beetles may also be exploited for survey of bark and ambrosia beetles, but trapping protocols must be adjusted depending on the forest type.

Bark beetles (sensu lato) colonize woody tissues like phloem or xylem and are associated with a broad range of micro-organisms. Specific fungi in the ascomycete orders Hypocreales, Microascales and Ophistomatales as well as the basidiomycete Russulales have been found to be of high importance for successful tree colonization and reproduction in many species. While fungal mutualisms are facultative for most phloem-colonizing bark beetles (sensu stricto), xylem-colonizing ambrosia beetles are long known to obligatorily depend on mutualistic fungi for nutrition of adults and larvae. Recently, a defensive role of fungal mutualists for their ambrosia beetle hosts was revealed: Few tested mutualists outcompeted other beetle-antagonistic fungi by their ability to produce, detoxify and metabolize ethanol, which is naturally occurring in stressed and/or dying trees that many ambrosia beetle species preferentially colonize. Here, we aim to test (i) how widespread beneficial effects of ethanol are among the independently evolved lineages of ambrosia beetle fungal mutualists and (ii) whether it is also present in common fungal symbionts of two bark beetle species (Ips typographus, Dendroctonus ponderosae) and some general fungal antagonists of bark and ambrosia beetle species. The majority of mutualistic ambrosia beetle fungi tested benefited (or at least were not harmed) by the presence of ethanol in terms of growth parameters (e.g., biomass), whereas fungal antagonists were inhibited. This confirms the competitive advantage of nutritional mutualists in the beetle’s preferred, ethanol-containing host material. Even though most bark beetle fungi are found in the same phylogenetic lineages and ancestral to the ambrosia beetle (sensu stricto) fungi, most of them were highly negatively affected by ethanol and only a nutritional mutualist of Dendroctonus ponderosae benefited, however. This suggests that ethanol tolerance is a derived trait in nutritional fungal mutualists, particularly in ambrosia beetles that show cooperative farming of their fungi.

Bark and ambrosia beetles (Curculionidae: Scolytinae), their phoretic mites (Acari) and associated Geosmithia species (Ascomycota: Hypocreales) from Virgilia trees in South Africa

The global spread of bark and ambrosia beetles (Coleoptera: Curculionidae), together with their symbiotic fungi, has become a major threat to forest health in recent years. Consequently, they have been extensively studied in many Northern Hemisphere countries where their species diversities are relatively well documented. In contrast, these insects have attracted relatively little research interest in the Southern Hemisphere. In this study we address this knowledge gap by cataloguing the bark and ambrosia beetle diversity of South Africa. More than 200 species of bark and ambrosia beetles were found to be present in the country, 16 of which are reported for the first time. This catalogue will provide a foundation for future surveys and studies on bark and ambrosia beetles not only in South Africa but also on the African continent.

1. Bark and ambrosia beetles are crucial for woody biomass decomposition in tropical forests worldwide. Despite that, quantitative data on their host specificity are scarce. 2. Bark and ambrosia beetles (Scolytinae and Platypodinae) were reared from 13 species of tropical trees representing 11 families from all major lineages of dicotyledonous plants. Standardised samples of beetle‐infested twigs, branches, trunks, and roots were taken from three individuals of each tree species growing in a lowland tropical rainforest in Papua New Guinea. 3. A total of 81 742 beetles from 74 species were reared, 67 of them identified. Local species richness of bark and ambrosia beetles was estimated at 80–92 species. 4. Ambrosia beetles were broad generalists as 95% of species did not show any preference for a particular host species or clade. Similarity of ambrosia beetle communities from different tree species was not correlated with phylogenetic distances between tree species. Similarity of ambrosia beetle communities from individual conspecific trees was not higher than that from heterospecific trees and different parts of the trees hosted similar ambrosia beetle communities, as only a few species preferred particular tree parts. 5. In contrast, phloeophagous bark beetles showed strict specificity to host plant genus or family. However, this guild was poor in species (12 species) and restricted to only three plant families (Moraceae, Myristicaceae, Sapindaceae). 6. Local diversity of both bark and ambrosia beetles is not driven by the local diversity of trees in tropical forests, since ambrosia beetles display no host specificity and bark beetles are species poor and restricted to a few plant families.

This research provides the first detailed assessment of Cistus ladanifer, a woody, perennial shrub native to the Mediterranean, as an invasive species in South Africa. Three small naturalising populations (all less than 0.1 ha) of this species were discovered in 2012 in native heathland vegetation (“Fynbos”) of the Western Cape Province of South Africa. Prior to this discovery, C. ladanifer had not previously been recorded or recognised as an invasive species in South Africa. It poses a significant threat to the local endemic vegetation, largely due to its pre-adaptation to similar environmental conditions, and, if left unmanaged, it has the potential to invade further. However, given the small size of currently known populations and its ease of management, we propose that eradication of C. ladanifer is feasible in South Africa. Here we provide insights into options for the management of C. ladanifer, in particular its eradication from South Africa. Based on the weed risk assessment presented here, we recommend that C. ladanifer be listed as an invasive species under national legislation, thus requiring compulsory management. The results of this study provide detailed information on the extent of the invasion by C. ladanifer and the aspects of its biology pertinent to management (e.g. its reproductive ability, soil-stored seed banks). We show that complete removal of C. ladanifer populations is feasible and results in a steady decline in population size over time. Local extirpation of populations of C. ladanifer can be enhanced through fire-stimulation of the seed bank, but this may not be feasible in an urban setting. Our study emphasises the importance of scientific research in the development and evaluation of species-based management plans for invasive species.

A Festschrift for Stephen L. Wood