Research Articles (Forestry and Agricultural Biotechnology Institute (FABI))

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Pseudoteratosphaeria supramediana sp. nov. (Teratosphaeriaceae, Mycosphaerellales), a new foliar pathogen on Eucalyptus in Indonesia
Pham, Nam Q.; Marincowitz, Seonju; Wingfield, Brenda D.; Crous, Pedro W.; Santos, Samuel A.; Duran, Alvaro; Tarigan, Marthin; Wingfield, Michael J. (Springer, 2026-02)
The Eucalyptus plantation industry in Indonesia has expanded rapidly during the last few decades. This growth is primarily attributed to the replacement of Acacia mangium, that was severely damaged by diseases. The rapid shift to large-scale monoculture plantations of Eucalyptus has introduced new challenges, particularly the emergence of new disease and pest problems. During routine Eucalyptus disease surveys in Indonesia, symptoms of a new leaf and shoot disease were observed on a single hybrid Eucalyptus grandis × pellita clone in Riau and Kalimantan. Leaf samples were collected, and isolations were made from the disease symptoms. Isolates were identified based on their morphological characteristics and DNA sequence data for seven loci. Phylogenetic analyses of the isolates revealed a novel species of Pseudoteratosphaeria, described here as Pseudoteratosphaeria supramediana sp. nov. A greenhouse pathogenicity test resulted in symptoms similar to those found under field conditions, and the inoculated fungus was consistently reisolated from the resulting lesions. Its appearance in two geographically distinct locations of Indonesia raises the possibility of multiple independent introductions of the pathogen.
Cold storage of Gonipterus platensis (Coleoptera: Curculionidae) eggs for Anaphes nitens (Hymenoptera: Mymaridae) rearing
Ribeiro, Murilo Fonseca; Cavallini, Gabriela; Solce, Gabriel Negri; Favoreto, Ana Laura; Passos, Jose Raimundo De Souza; Barbosa, Leonardo Rodrigues; Hurley, Brett Phillip; Wilcken, Carlos Frederico (PeerJ, Inc., 2026-03-13)
BACKGROUND : Anaphes nitens (Girault, 1928) (Hymenoptera: Mymaridae) is an egg parasitoid used for the biological control of Gonipterus spp. in regions where this pest is present. Cold storage of host eggs is a crucial strategy in biological control programs. This study aimed to evaluate the effects of cold storage on G. platensis eggs for laboratory rearing of both the host and its parasitoid, A. nitens. METHODS : Gonipterus platensis eggs, aged 1 and 3 days, were stored in a refrigerator at 7 ± 1 °C for 5, 10, 20, 30, 40, and 50 days in complete darkness. After each storage period, the eggs were transferred to a biochemical oxygen demand (BOD) chamber at 25 °C and hatching rates and larval survival were assessed. To evaluate parasitoid reproduction, fresh host eggs were stored at 7 ± 1 °C for 5, 10, 15, 20, and 25 days under dark conditions and subsequently exposed to A. nitens. Parasitism rate, sex ratio, and offspring longevity were recorded. RESULTS : Results showed that 1- and 3-day-old G. platensis eggs maintained the highest viability within the first 10 days of storage, with hatching rates exceeding 50% up to 20 days post-storage. A 20-day storage period was the longest duration that did not differ significantly from the non-stored eggs (control) considering A. nitens parasitism and progeny longevity when stored host eggs were offered. CONCLUSION : Therefore, storing host eggs for this period effectively supports colony maintenance while simultaneously facilitating parasitoid propagation.
Comparative population genetics of Exserohilum turcicum in smallholder farms of Kenya and Uganda
Mahlangu, Jabulile N.N.; Berger, David Kenneth; Nsibo, David Livingstone (Wiley, 2026-01)
Exserohilum turcicum, the causal agent of northern leaf blight (NLB), poses a major threat to maize production in sub-Saharan Africa. Effective disease management depends on understanding the biology and population genetic structure of the pathogen, yet studies from Africa remain limited. Here, we investigated the genetic diversity and evolutionary forces shaping E. turcicum populations in Kenya and Uganda. A total of 494 strains were genotyped using 12 microsatellite markers. Gene diversity was relatively low in Kenya (He = 0.45) and Uganda (He = 0.42) compared with previous reports. Analysis of molecular variance revealed weak but significant differentiation between countries (ΦPT = 0.178, p = 0.001), with more variation occurring within countries (82%) than among them (18%). Cluster analyses showed high levels of gene flow within each country but limited admixture between countries, suggesting geographical barriers to dispersal. Grouping populations according to shared agroecological zones did not result in distinct genetic clustering, indicating that population structure was not driven by agroecological similarity. This interpretation was supported by a weak isolation-by-distance correlation (R2 = 0.077), consistent with restricted long-distance gene flow. Most populations deviated from the expected 1:1 mating-type ratio, highlighting the importance of clonal reproduction in shaping population structure. Collectively, these findings suggest that E. turcicum populations are largely panmictic within countries but exhibit restricted cross-country movement. These results provide a valuable foundation for developing sustainable, regionally targeted strategies to manage NLB in East Africa.
Bodyguard interactions : a beneficial endophyte triggers emission of methyl salicylate in infested tomato plant mediating attraction of a parasitoid wasp
Akutse, Komivi S.; Agbessenou, Ayaovi; Yusuf, Abdullahi Ahmed; Khamis, Fathiya Mbarak (Springer, 2026-03-13)
The endoparasitoid Dolichogenidea gelechiidivoris is a potential candidate biocontrol agent of Phthorimaea absoluta. We previously reported that the endophyte Trichoderma asperellum M2RT4 triggers the systemic release of key phytohormones in tomato affecting the behavior and herbivory of P. absoluta. As D. gelechiidivoris uses odor cues to locate P. absoluta, we therefore investigated the chemical basis of interactions between D. gelechiidivoris, the tomato plant with and without endophyte and P. absoluta through bioassay-guided chemical analysis. Y-tube olfactometer bioassays showed that the parasitoid was significantly attracted to P. absoluta-infested tomato plants but did not show preference to colonized and colonized-infested plants. Coupled GC–MS analyses revealed both qualitative and quantitative differences in volatile emission between non-colonized, colonized, non-colonized infested and colonized-infested plants, where volatile emission rate increased with increasing infestation level. Methyl salicylate (MeSA) emission was significantly higher in colonized-infested than in colonized and non-colonized infested plants. Subsequent bioassays revealed attraction of the parasitoid to synthetic MeSA emitted at its natural release rate from endophytically-colonized infested plants. Our findings highlight the significant role played by MeSA, which mediates the attraction of D. gelechiidivoris thereby indirectly assisting tomato plants in combatting P. absoluta.
An evidence-based protocol for developing lists for tree planting
Potgieter, Luke J.; Cadotte, Marc W.; Kumschick, Sabrina; Paap, Trudy; Roets, Francois; Wilson, John R.U.; Richardson, David M. (Pensoft Publishers, 2025-11)
Tree-planting is increasingly being promoted for urban greening, carbon sequestration, and to enhance biodiversity. However, poorly planned and executed tree-planting schemes can inadvertently contribute to biological invasions with detrimental effects on local ecosystems, economies, and human well-being. Therefore, sustainable, rigorous, repeatable, and transparent species selection strategies are needed. We developed a strategic decision protocol for identifying tree taxa suitable for planting schemes, using a multi-criterion approach that integrates national lists of regulated invasive plant species, global evidence of invasiveness, and susceptibility to key pests. Using the Polyphagous Shot Hole Borer (PSHB) invasion in the City of Cape Town, South Africa as a case study, we illustrate the protocol’s application and potential for informing planting decisions. 444 tree taxa currently planted in Cape Town were assessed. Of these, 85 are regulated nationally as invasive species (and are prohibited from use), while 49 met all suitability criteria and were identified as candidates for a planting list (i.e., a safe list). This protocol provides evidence-based guidance for tree-planting to mitigate the risk of tree invasions and to reduce the spread and impact of associated pests and pathogens. This protocol is replicable and adaptable for use in other regions and can support environmental planners and managers in making informed decisions to safeguard ecosystems and optimise ecosystem services (e.g., which trees to plant in restoration initiatives).
Advancing the taxonomy of Sclerotinia (Helotiales, Sclerotiniaceae) : a review and recommendations for an important plant-pathogenic genus
Thomas, Chanel; Wilken, Pieter Markus; Coetzee, Martin Petrus Albertus; Visagie, Cobus M. (Pensoft Publishers, 2026)
Sclerotinia is a fungal genus of significant agricultural and scientific importance, as it includes multiple plant pathogens and provides an informative case study for mechanisms of host generalism. However, the taxonomy of this group remains unsettled, which hinders research on these pathogens. The last monographic treatment of Sclerotinia was published more than 40 years ago and was centered on the morphological data available at that time. Here, we examine that revision alongside other pivotal publications to trace the taxonomic history of Sclerotinia and to evaluate the morphological traits used to identify Sclerotinia species. We also briefly assess the composition of genera in the family Sclerotiniaceae, emphasising the need for a modern taxonomic investigation of the broader group. Thirteen new Sclerotinia species have been described since the last taxonomic revision, including Sclerotinia antarctica, S. asari, S. atrostipitata, S. cirsii-spinosissimi, S. ginseng, S. glacialis, S. himalayensis, S. nivalis, S. pseudoplatani, S. subarctica, S. tetraspora, S. trillii, and S. verrucispora. These species are evaluated here. Finally, several recommendations are made regarding how future taxonomic research on Sclerotinia should incorporate molecular data. We highlight potential obstacles and opportunities for this research, including the limitations of the internal transcribed spacer rDNA region (ITS) as a DNA barcode and the untapped potential of genomic data for the genus. By outlining the gaps that need to be addressed, this review charts a course toward a clearer understanding of taxonomic relationships among Sclerotinia species. This understanding will facilitate research into other aspects, such as pathogenicity and host generalism, and may ultimately contribute to improved management of the devastating diseases caused by these pathogens.
A weighted gene co-expression network analysis characterises the common defence responses of Eucalyptus to diverse biotic challenges
Swanepoel, Shae; Naidoo, Sanushka (Nature Research, 2026-02)
Eucalyptus is a globally important forestry genera cultivated for paper, pulp and biofuel production. These trees are increasingly threatened by a range of emerging pests and pathogens. While previous studies have focused on the transcriptomes of single Eucalyptus-pathogen interactions, the core transcriptional networks underlying defence across multiple biotic challenges remain poorly understood. Here we integrated 180 Eucalyptus-biotic stress RNA-sequencing libraries to characterise the common defence gene network during interactions with five distinct pathosystems. We constructed a comprehensive weighted gene co-expression network and identified 38 modules of highly co-expressed genes consisting of between 40 and 3,328 genes. The network revealed distinct modules that were induced by pathogen infection, enriched for defence responses including salicylic acid signalling and secondary metabolite biosynthesis and notably nitrate transport and responses, suggesting a potential link between nitrogen metabolism and immunity. Transcription factor enrichment analysis highlighted WRKY family genes as key regulators of induced responses, with WRKY6 emerging as a candidate hub gene in broad-spectrum resistance. Together, this study provides the first integrative transcriptome network of Eucalyptus responses to diverse biotic stressors, and offers candidate genes and pathways for future functional validation to enhance disease resistance resource in long-lived trees.
Pinus-derived membrane vesicles disrupt pathogenic metabolism in fungi
Kunene, Sithembile; Mmushi, Tshepo Joseph; Steenkamp, Emma Theodora; Motaung, Thabiso Eric (Wiley, 2026)
• Much of what we know about the biological impacts of vesicles (MVs) is derived from Arabidopsis thaliana. Our study focused on vesicles from species in the non-model plant group, Pinus (pine) (P. elliottii, P. radiata, and P. patula × Pinus tec (hybrid)). These plants have tougher tissues and strong, acicular-shaped leaves (needles). • Herein, we first developed a protocol to guide effective collection of juice fluid from needles and roots in a clean and efficient manner. The effects of these vesicles were characterized in terms of the global nutrient profile of the pine pitch canker fungus, Fusarium circinatum, generated from growing fungal spores on ~400 substrates embedded across BioLog phenotypic microarray (PM) plates (PM1, PM2A: carbon sources; PM3B: nitrogen sources; PM9: osmolytes/pH; PM24C: chemicals). • Our findings revealed that MVs, specifically needle-derived MVs (ndMVs) from P. elliottii, disrupt metabolite assimilation in several important pathways, including carbon and nitrogen metabolism. The PM data were also strongly correlated with observed phenotypic effects, including reduced viability and germination of spores in liquid media, as well as impaired filamentous growth on solid media. Importantly, these MV-induced phenotypic effects were reproducible in other filamentous pathogens (e.g., Botrytis cinerea, Chrysoporthe cubensis and F. graminearum) and during a glasshouse trial conducted with F. circinatum-infected P. elliottii seedlings, demonstrating the stable biological effects of ndMVs. • Cumulatively, our results suggest that plant-derived vesicles can disrupt metabolism in pathogenic fungi and, therefore, serve as a cost-effective and sustainable source of novel plant protection molecules.
Genome resources of Xanthomonas vasicola strains from various hosts : reference-guided chromosome and plasmid assemblies for enhanced pathogen genomics
Zim, Nomakula Y.; Yssel, Anna E.J.; Coutinho, Teresa A. (Springer, 2026)
No abstract available.
Genome and transcriptome-based identification and expression profiling of chemosensory gene families across developmental stages and tissues in Sirex noctilio (Hymenoptera: Siricidae)
Postma, Alisa; Klynsmith, Leandri; Duong, Tuan A.; Allison, Jeremy D.; Smidt, Werner; Waterhouse, Robert M.; Lesny, Peter; Oeyen, Jan Philip; Petersen, Malte; Martin, Sebastian; Liu, Shanlin; Zhou, Xin; Ziesmann, Tanja; Donath, Alexander; Mayer, Christoph; Misof, Bernhard; Niehuis, Oliver; Peters, Ralph S.; Podsiadlowski, Lars; Coetzee, Martin Petrus Albertus; Joubert, Fourie; Slippers, Bernard (Wiley, 2026)
The Sirex woodwasp (Sirex noctilio; Hymenoptera: Siricidae) is among the most destructive invasive pests affecting Pinus plantations worldwide. Chemosensory systems offer promising targets for pest control strategies. The identification and characterization of chemosensation genes in non-model, economically significant insects such as S. noctilio, is an important first step towards the development of such control methods. Here we sequenced and assembled a draft genome of S. noctilio and performed RNA-sequencing of 15 olfactory and non-olfactory tissues to study the expression patterns of chemosensation-related genes. Specific genes, such as SnocOR16 and SnocSNMP1, displayed tissue- and sex-specific expression patterns, making them particularly intriguing for their potential roles in chemosensation and oviposition. As woodwasps and their related lineages form a sister group to the majority of other Hymenoptera, including Apocrita, insights into their gene repertoires are crucial for tracing the evolutionary history of chemosensory multigene families of this ecologically and economically significant insect order. This study enhances our understanding of the molecular mechanisms underlying S. noctilio chemosensation, paving the way for further research in chemical ecology and the functional characterization of S. noctilio chemosensation genes.
Genome analyses reveal two novel species of Seiridium from Acacia mearnsii
Aylward, Janneke; Visagie, Cobus M.; Roets, Francois; Wingfield, Brenda D.; Wingfield, Michael J. (Springer, 2026-02)
Seiridium is a genus of Sordariomycetes (Amphisphaeriales, Sporocadaceae), primarily known for species that cause cypress canker on Cupressaceae trees. However, most species in this genus have been reported from angiosperms, including many species in the native range of their hosts. Several unidentified Seiridium strains, collected > 20 years ago from Acacia mearnsii trees in eastern South Africa and southeastern Australia, were recently recovered from a collection of preserved cultures. We considered the phylogenetic position of these Seiridium strains and assessed their pathogenicity on A. mearnsii. Maximum likelihood analysis of three concatenated gene regions revealed four well-supported clades. Two closely related clades corresponded to Australian and South African origins, whereas two other clades representing South African isolates formed a monophyletic group with S. kartense, a species known from Eucalyptus cladocalyx on Kangaroo Island in Australia. Genome-wide average pairwise nucleotide identity and genetic differentiation analysis supported three species, including isolates considered conspecific with S. kartense and two that we consider to represent new species. These are described and named here as Seiridium mearnsii sp. nov. and Seiridium rouxiae sp. nov. Inoculations with South African isolates failed to produce evidence of pathogenicity. Seiridium species from A. mearnsii have likely been introduced into South Africa from Australia, along with the planting material used to establish A. mearnsii forestry.
A haplotype-resolved reference genome for Eucalyptus grandis
Lötter, Anneri; Bruna, Tomas; Duong, Tuan A.; Barry, Kerrie; Lipzen, Anna; Daum, Chris; Yoshinaga, Yuko; Grimwood, Jane; Jenkins, Jerry W.; Talag, Jayson; Borevitz, Justin; Lovell , John T.; Schmutz, Jeremy; Wegrzyn, Jill L.; Myburg, Alexander A. (Oxford University Press, 2025-07)
Eucalyptus grandis is a hardwood tree used worldwide as pure species or hybrid partner to breed fast-growing plantation forestry crops that serve as feedstocks of timber and lignocellulosic biomass for pulp, paper, biomaterials, and biorefinery products. The current v2.0 genome reference for the species served as the first reference for the genus and has helped drive the development of molecular breeding tools for eucalypts. Using PacBio HiFi long reads and Omni-C proximity ligation sequencing, we produced an improved, haplotype-phased assembly (v4.0) for TAG0014, an early-generation selection of E. grandis. The 2 haplotypes are 571 Mbp (HAP1) and 552 Mbp (HAP2) in size and consist of 37 and 46 contigs scaffolded onto 11 chromosomes (contig N50 of 28.9 and 16.7 Mbp), respectively. These haplotype assemblies are 70–90 Mbp smaller than the diploid v2.0 assembly but capture all except one of the 22 telomeres, suggesting that substantial redundant sequence was included in the previous assembly. A total of 35,929 (HAP1) and 35,583 (HAP2) gene models were annotated, of which 438 and 472 contain long introns (>10 kbp) in gene models previously (v2.0) identified as multiple smaller genes. These and other improvements have increased gene annotation completeness levels from 93.8 to 99.4% in the v4.0 assembly. We found that 6,493 and 6,346 genes are within tandem duplicate arrays (HAP1 and HAP2, respectively, 18.4 and 17.8% of the total) and >43.8% of the haplotype assemblies consists of repeat elements. Analysis of synteny between the haplotypes and the E. grandis v2.0 reference genome revealed extensive regions of collinearity, but also some major rearrangements, and provided a preview of population and pangenome variation in the species.
Both synergism and interaction diversity explain the mixtures of defensive monoterpenes in spruce oleoresin
Zaman, Rashaduz; Jain, Akanksha; Hammerbacher, Almuth; Gershenzon, Jonathan; Kandasamy, Dineshkumar (Wiley, 2025-09)
1. Chemical defences, such as the monoterpenes of conifer oleoresin, frequently occur as complex blends of many components, but the selective pressures that maintain these mixtures are not yet known. Several theories attempt to explain the existence of chemical defence mixtures in plants. However, due to limited empirical evidence, it is unclear which theories might best apply. 2. Here, we tested the vapour phase activity of 12 individual Norway spruce monoterpenes and their naturally occurring mixtures to two types of natural spruce enemies, the adult Eurasian spruce bark beetles, Ips typographus, and their three major symbiotic fungi, using survival and growth bioassays. Next, we evaluated whether spruce trees could alter their monoterpene profile in response to fungal infection. 3. Individual monoterpenes had generally opposite effects on bark beetles compared to symbiotic fungi. The compounds that were most toxic to beetles were the least inhibitory to fungal growth and vice versa. The least abundant monoterpenes had the strongest activity against beetles or fungi, while the most abundant monoterpenes showed intermediate activity against both groups of enemies. Additionally, the activity of monoterpene mixtures was significantly stronger against beetles and some symbiotic fungi than the additive effects of individual compounds. Among the symbiotic fungi tested, one (Grosmannia penicillata) exhibited high tolerance to monoterpenes, and its growth was even stimulated by the monoterpenes most toxic to the beetle. Interestingly, spruce bark responded to G. penicillata inoculation by accumulating higher concentrations of specifically fungistatic monoterpenes. 4.Our results support the predictions of the interaction diversity hypothesis, which posits that defence mixtures are maintained in plants because the individual components target different attackers, as well as the synergy hypothesis, which predicts that mixtures will exhibit stronger activity than single compounds. Thus, these two theories may deserve increased emphasis in explaining the widespread occurrence of mixtures in plant chemical defence.
The effects of host and habitat preferences in mate location of Monochamus maculosus, Monochamus notatus, and Monochamus scutellatus (Coleoptera: Cerambycidae)
Andrade, Samara M.M.; Dutkiewicz, David; Borges, Marcelo E.; Smith, Sandy M.; Allison, Jeremy D. (Cambridge University Press, 2026-02)
Several Monochamus species (Coleoptera: Cerambycidae) use monochamol as an aggregation-sex pheromone, raising questions about how they maintain reproductive isolation. Herbivorous insects use host plant semiochemicals as cues for mate location and, with or without habitat cues, these could confer reproductive isolation among sympatric Monochamus spp. To test this hypothesis, host and habitat preferences in mate location were examined for sympatric populations of Monochamus maculosus, Monochamus notatus, and Monochamus scutellatus in the Algoma District, Ontario, Canada. Field experiments were performed to investigate whether differences in host preference, vertical distribution across the forest canopy, spatial distribution within down and standing dead trees, or any combination of these factors could minimise cross-attraction to monochamol. Results showed that more M. maculosus were attracted to monochamol combined with jack pine foliage than with balsam fir or white spruce, whereas no differences in host attractivity were observed for the other species. Vertical abundance of M. maculosus and M. scutellatus was similar across forests. Spatial distribution provided limited evidence for species segregation within hosts. No evidence was found that host or habitat preferences contribute to reproductive isolation in M. maculosus, M. notatus, or M. scutellatus, suggesting that vertical distribution could be driven by resource availability.
Proteomic and secretomic response of an African Armillaria species to iron
Narh, Deborah L.; Wingfield, Brenda D.; Coetzee, Martin Petrus Albertus (American Chemical Society, 2026-03)
Armillaria species have attracted considerable research interest, because they are widely distributed, mostly plant-pathogenic, and exhibit unique characteristics. Abiotic factors influence intra- and interspecies variations in pathogenicity and/or virulence of these fungi. However, the mechanisms involved in causing these variations are not well understood. Iron is an indispensable element in several molecular and biological processes. Yet, excessive abundance of iron can be toxic to organisms due to Fenton-like reactions. This study aimed to gain insights into the type and extent of iron-responsive proteomic and secretomic changes in Armillaria sp. strain CMW4456 cultured in liquid media supplemented with iron using a multiomics approach. Significant iron-dependent alterations of proteins involved in metabolism and growth were observed in the proteomes and secretomes. Iron supplementation at 100 μM did not elicit an oxidative stress response by the fungus. Our analyses revealed three putative siderophore biosynthetic gene clusters (BGCs) in the genome and expression of proteins encoded by some BGC genes in the proteome. This knowledge contributes to a better understanding of the mechanisms employed by an Armillaria sp. in response to iron, gives insights into possible modes for inhibiting or attenuating the pathogenicity and/or virulence of Armillaria spp., and can be valorized for more biotechnological applications.
Editorial : Forest microbiome : dynamics and interactions in the anthropocene era
Chakraborty, Amrita; Roy, Amit; He, Shulin; Castellano-Hinojosa, Antonio; Asiegbu, Fred O.; Coutinho, Teresa A. (Frontiers Media, 2025-11-21)
Forests represent one of the most complex and biodiverse ecosystems on Earth, with intricate networks linking trees, vegetation strata, insects, microbial communities, and soil processes. These networks, sustained by feedback loops and finely tuned ecological balances, form the foundation of global biogeochemical cycles and biodiversity conservation. At the core of these dynamics lies the forest microbiome, including a vast, often invisible consortium of bacteria, fungi, archaea, and viruses that mediates nutrient turnover, supports tree health, and shapes interactions across trophic levels (Baldrian, 2017; Asiegbu and Kovalchuk, 2021).
Outbreaks of a native jewel beetle, Agrilus grandis (Coleoptera: Buprestidae), on commercial black wattle, Acaciamearnsii, plantations in South Africa
Nel, Wilma Janine; Jali, Sandisiwe; Barnes, Irene; Wondafrash, Mesfin; Hurley, Brett Phillip (Entomological Society of Southern Africa, 2026-02)
In early 2024, an outbreak of an unknown wood-borer was observed in Acacia mearnsii De Wild (black wattle) compartments in the Midlands of KwaZulu-Natal, South Africa, causing symptoms of excessive resin production. Larvae uncovered beneath the bark were morphologically identified as a flathead borer, prompting urgent investigation due to the historically low impact of wood-borers on black wattle in South Africa. DNA sequencing of the COI and CytB regions of the larvae failed to yield conclusive matches, so infested logs were collected and the infesting insects reared, resulting in the emergence of three adult beetles. Morphological examination of the adults revealed them as being Agrilus grandis Gory & Laporte 1839, a native African jewel beetle. Comparison to historical specimens housed in the FABI Insect Reference Collection based at the University of Pretoria revealed a previous, unpublished outbreak of the same species in Acacia mearnsii in 1974. However, this is the first official report of A. grandis infestations on A. mearnsii in South Africa.
Vulnerabilities of parasitoid-mediated biocontrol to climate stress
Lyberger, Kelsey P.; Machekano, Honest; Khan, Md Kawsar (Elsevier, 2026-06)
Climate change threatens vital ecosystem services, including biological control mediated by parasitoids. As higher-trophic-level organisms, parasitoids, compared to their hosts, are disproportionately vulnerable to climatic stress because their survival depends on both their own physiology and that of their hosts. This review synthesizes how rising temperatures reconfigure host–parasitoid interactions, with outcomes that are system-dependent. Common disruptions include reduced parasitism success due to narrower parasitoid thermal tolerance, phenological mismatches that desynchronize life cycles, and altered overwintering activity. As these shifts can undermine both natural and artificial biological control, elevating pest outbreak risks and threatening agroecosystem stability, we discuss how mitigating them may require adapting current biocontrol strategies. HIGHLIGHTS • Parasitoids often exhibit narrower thermal windows than their hosts. • Warming differentially alters host and parasitoid development and longevity, increasing chances of phenological mismatch. • Climate change may reduce overwintering survival in parasitoids and their ability to regulate host populations. • Warming may reduce parasitism success, impacting both artificial and natural biocontrol.
Draft genome sequences of Rahnella perminowiae, R. aceris, and R. aquatilis isolated from onion bulbs (Allium cepa L.) displaying symptoms of bacterial rot
Mnguni, Fanele Cabangile; Shin, Gi Yoon; Aegerter, Brenna J.; Du Toit, Lindsey J.; Derie, Michael L.; Coutinho, Teresa A. (Springer, 2026-02)
Onions (Allium cepa L.) are among the most widely produced vegetables globally, and their cultivation plays an important role in food security (Schwartz et al. 2007). However, the emergence of opportunistic bacterial plant pathogens, such as Rahnella species, which are not fully understood yet, poses a threat to onion production (Asselin et al. 2019; Brady et al. 2022). Rahnella species are Gram-negative, facultative anaerobes within the Yersiniaceae family, part of the order Enterobacteriales (Adeolu et al. 2016). According to the List of Prokaryotic Names with Standing in Nomenclature (LPSN), the genus consists of 15 described species that are isolated from various environments and are considered validly characterised (Guo et al. 2012; Brady et al. 2014; Lee et al. 2019; Liang et al. 2020).
Structural insights into WY domain SLiM-containing conserved RxLR effectors : a case study of five important Phytophthora species
Salasini, Brenda Chisanga; Chepsergon, Jane; Nxumalo, Celiwe Innocentia; Moleleki, Lucy Novungayo (American Phytopathological Society, 2026)
Pathogenicity in Phytophthora species is in part underpinned by a sophisticated arsenal of RxLR effectors, which function as molecular determinants of host immune manipulation. Among these, conserved RxLR effectors (CREs) represent an evolutionarily conserved subset that is indispensable for virulence. However, the structural basis of their function remains poorly understood. Here, we conducted in silico analysis of CREs across five agriculturally significant Phytophthora species, revealing a conserved subset that integrates WY domains with embedded short linear motifs (SLiMs), a previously recognized architectural feature with functional implications. Notably, our findings indicate that despite the canonical association of SLiMs with intrinsically disordered regions, their incorporation within the structured WY domain preserves domain integrity while potentially expanding the effector's interactome within host cells. To explore the functional relevance of this domain organization, we characterized Phytophthora nicotianae RxLR6 (PpRxLR6), a representative WY-SLiM CRE identified in this study. Using Agrobacterium-mediated transient expression assays, we demonstrate that PpRxLR6 activates key immune defense networks in Nicotiana and Solanum species, suggesting a role in modulating host immune signaling. Structural predictions further reveal that PpRxLR6 harbors its SLiM within a well-ordered WY-like helical core region, suggesting that SLiM-mediated interactions may occur within structured effector domains rather than being confined to intrinsically disordered regions. These findings enhance our understanding of the effector domain architecture of PpRxLR6, illustrating how structured domains in CREs may serve as scaffolds for SLiM-mediated interactions. This structural arrangement may represent an adaptive strategy in Phytophthora evolution, potentially enhancing effector versatility in host interactions and immune modulation.

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