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• Introduction The Eucalyptus Weevil (Gonipterus “scutellatus” Gyllenhal) is a notorious pest of eucalypt plantations around the world, but its host range differs across its area of introduction, which may be due to it being a complex of several cryptic species. • Objectives The performance of the weevil was tested on 14 Eucalyptus and one Syzygium species in the laboratory and the field in South Africa. • Results The Weevil exhibited different levels of polyphagy, depending on how the host plants were presented: as bouquets or sleeved branches, in choice or no-choice combinations or in the open field. The fundamental host range in the laboratory was found to be broader than the realized host range in the field. Eucalyptus smithii was found to be the preferred host while Eucalyptus saligna and the native Syzygium myrtifolia were immune to both feeding and oviposition. Adult feeding and oviposition were more selective in the field, and the larvae were found to be less discriminating than the adults. • Conclusions The weevil is shown to have a narrow host range within two sections of the subgenus Symphyomyrtus, a finding that could contribute to resolution of the taxonomy of the genus Eucalyptus. Further, it suggests that countries that already have the pest may be susceptible to introductions of additional Gonipterus species. KeywordsHost preference–Host specificity–Realized and fundamental host range–Resistant species
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... Among the eucalypt species regularly sampled in this study, there seems to be a preference for E. propinqua over E. dunnii as hosts of Gonipterus, given the higher number of egg capsules and adults found E. propinqua, with E. nicholii intermediate in preference. These results, however, must be interpreted locally, taking into account the eucalypt and Gonipterus species composition in the area before a conclusion regarding preference can be reached (Clarke et al., 1998;Newete et al., 2011). Studies of G. platensis and Gonipterus sp. ...
... Studies of G. platensis and Gonipterus sp. n. 2. have shown a general tendency of these species to prefer feeding on trees of the subgenus Symphyomyrtus, particularly those in the section Maidenaria (Newete et al., 2011;Gonçalves et al., 2019), to which E. dunnii and E. nicholii belong. E. propinqua, which belongs in the section Latoangulatae, has been shown to sustain G. sp. ...
... E. propinqua, which belongs in the section Latoangulatae, has been shown to sustain G. sp. n. 2 adult feeding but not oviposition (Newete et al., 2011). In our study, most adults found on E. propinqua were G. sp. ...
Article
Gonipterus is a genus of defoliating weevils that causes significant impact in commercially grown eucalypts in their native range in southern Australia and as invasive pests in Western Australia and several countries overseas. The diversity of species in this genus is still in the process of discovery, and in subtropical Australia, its diversity and ecological parameters are largely unknown. We surveyed Gonipterus phenology, species composition and trophic associations in South East Queensland, where little has been recorded about this genus. Surveys were conducted once a month in a non-commercial plantation of native eucalypts, where three species of trees were sampled regularly and others checked on an ad hoc basis. On each sampling occasion, adult weevils, larvae and egg capsules were collected, adults identified, larvae reared and egg capsules individualized in small containers for emergence of larvae and parasitoids. Two peaks of egg-laying occurred, whereas numbers of adults and larvae had only one peak each. Six species of Gonipterus were collected: two described but in need of revision, two undescribed but previously recognized and two undescribed and hitherto unrecognized, each with a different pattern of host–tree association. Three egg-parasitoid species, Anaphes nitens, Centrodora damoni and Euderus sp. were reared from egg capsules, varying in prevalence according to the tree species from which the eggs were collected.
... Threats from forest pests and diseases are of major apprehension to South Africa's commercial forestry sector (Oumar and Mutanga 2014). Gonipterus scutellatus, commonly known as the eucalyptus snout beetle, is a leaf-feeding pest that has spread throughout South Africa's commercial forests (Newete, Oberprieler, and Byrne 2011). The beetle is a specialist on the species eucalyptus (Newete, Oberprieler, and Byrne 2011), which are the most productive commercially planted tree species found in the country (Adam, Mutanga, and Ismail 2013). ...
... Gonipterus scutellatus, commonly known as the eucalyptus snout beetle, is a leaf-feeding pest that has spread throughout South Africa's commercial forests (Newete, Oberprieler, and Byrne 2011). The beetle is a specialist on the species eucalyptus (Newete, Oberprieler, and Byrne 2011), which are the most productive commercially planted tree species found in the country (Adam, Mutanga, and Ismail 2013). Therefore, managing the impacts of the beetle must be prioritized to mitigate its potential impacts. ...
... Therefore, managing the impacts of the beetle must be prioritized to mitigate its potential impacts. Attempts to control the beetle in South Africa were made in 1949 when the egg parasitic wasp Anaphes nitens was first used as a biological control measure (Newete, Oberprieler, and Byrne 2011;Tooke 1955). However, South Africa's environmental conditions still endorse the spread of the beetle, even in the presence of the wasp, therefore requiring alternative control and monitoring measures (Loch and Floyd 2001). ...
Article
Gonipterus scutellatus is a beetle causing severe defoliation to South Africa’s eucalyptus plantations. This defoliation induced by the beetle inhibits the eucalypts ability to photosynthesize, by affecting its chlorophyll content. Therefore, this study integrates spatially optimized and the single 0.5 m resolution vegetation indices with sparse partial least squares regression (SPLS-R) and partial least squares regression (PLS-R) to detect and map leaf chlorophyll content of defoliated eucalyptus plantations. The optimized vegetation indices were spatially resampled to resolutions that best paralleled varying levels of G. scutellatus defoliation. From the results, the 0.5 m resolution SPLS-R model (R ² = 0.76; RMSE of 1.50 (2.88% of the mean measured chlorophyll)) outcompeted the 0.5 m resolution PLS-R (R ² = 0.73; RMSE of 1.54 (2.95% of the mean measured chlorophyll)) model. Furthermore, the spatially optimized SPLS-R (R ² = 0.81; RMSE of 1.44 (2.76% of the mean measured chlorophyll) model was more superior in detecting and mapping chlorophyll content of defoliated eucalyptus plantations when compared to the 0.5 m resolution SPLS-R model. The most significant variables selected by the optimized SPLS-R model were DMI, ARI, NDRE, GNDVI, and NDVI. In essence, this study has illustrated the significance of the spatial resolution in effectively detecting and mapping chlorophyll content of defoliated eucalyptus plantations.
... Of particular interest here is forest damage caused by Gonipterus scutellatus (Coleoptera: Curculionidae), commonly known as Eucalyptus snout beetle. This insect is a leaf-feeding weevil native to south-east Australia that has been accidently introduced in other parts of the world including South Africa, where it has become a major defoliator of Eucalyptus trees (Clarke et al., 1998;Newete et al., 2011). Locally, the weevil was first detected in 1916 and has since proliferated to several Eucalyptus production areas (Tooke, 1955). ...
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Eucalyptus plantations are an important contributor to the South African economy and are geographically concentrated in the productive Zululand region. However, this area is becoming increasingly vulnerable to various forest disturbances such as insect attacks and drought. Information of the location, extent and duration of insect infestation is therefore crucial for sustainable timber production and forest management planning, and remote sensing approaches have been successful in the retrieval and analysis of such information along with field surveys. Sappi Forests frequently conduct field surveys to establish the nature of disturbances to improve the performance of trees, as these may be difficult to distinguish from other disturbances such as droughts. Great effort has been made to remotely detect the impact of G. scutellatus using single-date high-resolution commercial satellites, whose application is restricted by high costs. Here, we compare the performance of spectral indices for detecting the impact of G. scutellatus infestation in KwaMbonambi plantations using publicly available Landsat data and also apply anomaly detection framework to further test their performance for detecting the impact of insect damage on trees and other disturbances that occurred on the same compartment over time. Our results showed high performance of short-wave infrared (SWIR) band for detecting the impact of insect damage, followed by the normalized difference infrared index (NDII) and normalized difference vegetation index NDVI, when anomaly detection was applied. Without anomaly detection, the spectral indicators showed changes even to drought impact in 2015, which did not when anomaly detection was used. We believe that indices containing the SWIR would perform better for detecting anomalous changes, and further research is required to explore this. Anomaly detection only showed the impact of insect damage and clearcutting as anomalous changes. Overall, we demonstrated the benefit of identifying vegetation anomalies caused by the impact of insect damage and other disturbances using freely available Landsat time-series data, particularly in data-poor regions that have restricted computational resources.
... Such differences could represent cues for their natural enemies and influence their level of success as biocontrollers (Schröder et al., 2020). Furthermore, results of previous studies suggest interspecific differences in environmental and host preferences of the beetles (Newete et al., 2011;Oliveira et al., 2022;Riquelme Virgala et al., 2018), which could guide when deciding on the species of Eucalyptus to be planted. ...
Article
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Eucalyptus snout beetles are a complex of at least eight cryptic species (Curculionidae: Gonipterus scutellatus complex), native to mainland Australia and Tasmania, that defoli-ate Eucalyptus trees and are considered important pests. Since the 19th century, three species of the complex have been introduced to other continents. Here, we document the presence of Eucalyptus snout beetles in Ecuador. We used DNA data for species identification and unambiguously demonstrated that the Ecuadorian specimens belong to the species Gonipterus platensis, which has low genetic diversity compared with other species in the complex. We analyzed G. platensis' potential distribution in South America with ecological niche models and found several areas of high to intermediate climatic suitability, even in countries where the pest has not been registered, like Peru and Bolivia. Accurate identification of species in the G. scutellatus complex and understanding of their potential distribution are essential tools for improved management and prevention tactics. K E Y W O R D S ecological niche model, forest pest, Gonipterus platensis, invasive species
... Sin embargo, en 2008 Loch cuando estudiaba el parasitismo de los huevos de G. scutellatus por una avispa en Australia, tuvo la sospecha de la existencia de más de una especie debido a que observó diferencias entre genitalias de machos y en la sincronía entre el parasitoide y el hospedero. Posteriormente, en 2011 Newete confirmó que G. "scutellatus" en realidad comprendia un complejo de al menos diez especies muy similares (en gran parte crípticas) que se habian confundido en toda la literatura anterior" (Newete, 2011). ...
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En Colombia se estima que existen 114.419 hectáreas plantadas de eucalipto, lo que representa el 21.9% del total plantado a nivel nacional, siendo las especies con mayor extensión E. grandis (40.879 ha), E. pellita (34.489 ha), E. urophylla (14.940 ha), E. tereticornis (10.042 ha), E. globulus (8.595 ha) y E. camaldulensis (2.690 ha) (Minagricultura, 2022). Una de las plagas más importantes en plantaciones es el llamado ˝gorgojo del eucalipto˝ Gonipterus scutellatus Gyllenhal, 1833 (Coleoptera: Curculionidae, Gonipterinae), el cual es originario de Australia y Tasmania (Marelli, 1926). Los especímenes tipo con el registro más antiguo para este insecto, (segun Online Zoological Collections of Australian Museums (OZCAM)), se encuentran en el Museo Victoria (Australia) con dos ejemplares adultos colectados en 1902. La importancia económica de G. plantesis radica en el daño causado por el adulto a las hojas de los árboles de eucalipto causando defoliación de la copa (tercio superior), crecimiento epicórmico y atrofia. Adicionalmente, los estadios larvales consumen las hojas jóvenes, que se encuentran principalmente en el tercio superior de la corona. Algunos investigadores consideran que aunque los adultos se alimentan de los bordes de las hojas maduras, la etapa larvaria es la etapa de alimentación más dañina (Adame et al. 2022).
... 22 However, there have been no NIR studies to date on the Gonipterini tribe, which includes a number of species which are economically significant pests of Eucalyptus plantations. [23][24][25] Furthermore, this tribe contains many cryptic species which are difficult to discriminate based on their external appearance. 26,27 Hence chemotaxonomic profiling using rapid techniques such as NIR spectroscopy could be greatly beneficial for discriminating between different species without requiring traditional, dissectionbased morphological methods. ...
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This proof-of-concept study aimed to investigate the potential of using near infrared (NIR) spectroscopy to discriminate between genera of Gonipterini weevil. NIR spectra (10,000–4,000 cm ⁻¹ ) were collected from 15 Gonipterini specimens, comprising three genera and five species. Principal component analysis (PCA) highlighted the inter-specific variation in NIR spectra, with separation observed between most species across the first two principal components. Partial least squares discriminant analysis (PLS-DA) could be used to differentiate between the genera (78% accuracy), although support vector machine (SVM) modelling gave improved accuracy (91%). The results support the prospect of NIR spectroscopy for the rapid discrimination between Gonipterini genera.
... It was, therefore, the preferred species to plant around Johannesburg, a city often referred to as the 'city of gold', where to this day several tailings dams with eucalypts trees are still conspicuous on the skyline of the city. This is because of the tree's fast growth rate and its ability to thrive in a wide range of climatic conditions, including soils contaminated with Acid Mine Drainage (AMD), and other metal pollutants (Newete et al., 2011;Carbonnier et al., 2004). ...
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Invasive alien plants are considered as a major threat to many ecological and socioeconomic systems. Nevertheless, the management of some of these plants is often controversial due to the positive socioeconomic and ecosystem roles they play. This necessitates proper mapping and monitoring of the extent and spatial distribution of such plants to prioritize resource allocation and management. However, mapping plant species using remote sensing in a heterogeneous environment such as an urban area is often challenged by high levels of spectral muddle. This study investigated the utility of the high and medium spectral and spatial resolution imageries from the WorldView-2 (WV-2) and SPOT-7 satellites, respectively , to map eucalypts trees in urban areas. Furthermore, the classification performances of Random Forest (RF) and Support Vector Machines (SVM) were compared. Both WV-2 and SPOT-7 imageries attained overall accuracies of 81.67% (0.78 kappa) and 72.78% (0.67 kappa), respectively, when the RF algorithm was used and 80% (0.76 Kappa) and 71.11% (0.65 Kappa), respectively when SVM algorithm was used. The user's accuracies for the eucalypts class in both WV-2 and SPOT 7 imageries were 73.33% and 60%, respectively, for the RF and 70% and 56.67% for the SVM algorithm, respectively. Thus, WV-2 imagery is more suitable for mapping eucalypts trees in a heterogeneous urban environment. Therefore, the classification of WV-2 imageries using RF produced a relatively more accurate map of the eucalypts trees for the study areas, the southern part of Johannesburg city. Ó 2020 National Authority for Remote Sensing and Space Sciences. Production and hosting by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).
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This pest survey card was prepared in the context of the EFSA mandate on plant pest surveillance (M-2020-0114), at the request of the European Commission. Its purpose is to guide the Member States in preparing data and information for designing statistically sound and risk-based surveys of the Gonipterus scutellatus species complex (Coleoptera: Curculionidae), in line with current international standards. It is a protected zone quarantine pest in the Azores (except Terceira Island) and Greece. The Gonipterus scutellatus species complex comprises 10 cryptic species. Species of the complex occur in Australia, New Zealand, South Africa, Madagascar, the Americas, and Europe (Portugal, Spain, France and Italy). Adults emerge and mate in late winter/spring and feed on eucalypt foliage. Females lay eggs on the foliage in clusters. Larvae develop through four instars. Pupation takes place in the soil. Adults overwinter, and they may aestivate. In Europe, two generations are completed, one in spring, and the other in summer or autumn. Adults and larvae feed exclusively on Eucalyptus species. Climatic conditions in the protected zones are likely suitable for the establishment of the insect, and all the predominant eucalypt species occurring in those areas are susceptible. The natural spread by flying adults can be expected to be a few km per year. Spread can be facilitated by the trade of eucalypt timber and by hitchhiking in containers. Detection and delimiting surveys should be conducted visually searching for symptoms and signs including defoliation of the crown, scalloped margins on eucalypt leaves, marks left on leaves by grazing larvae, or thread-like larval frass. The G. scutellatus species complex and the species within the complex can be identified by morphology or molecular barcoding.
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Gonipterus sp. n. 2 (Coleoptera, Curculionidae) is an invasive, commercially important weevil that causes large-scale defoliation of Eucalyptus trees. The weevil specifically feeds on young leaves and new shoots, thus reducing tree growth. The weevil displays a very strong preference for certain Eucalyptus genotypes, however, this behaviour and the chemistry underlying it is poorly understood, thereby complicating the selection of resistant trees. To elucidate the feeding preference of Gonipterus sp. n. 2, we assessed the relative levels of susceptibility of 62 Eucalyptus genotypes from 23 species using a laboratory choice assay. This revealed large intraspecific variation in susceptibility to weevil feeding, which for certain species, exceeded the interspecific variation. A semiquantitative metabolite profile analysis on 13 genotypes revealed strong correlations of 10 metabolites to feeding damage. The behavioural effects of the identified compounds were assessed through an in vitro feeding preference assay using artificial diets as well as under field conditions. This revealed three phagostimulants (1,8-cineole, oxalic acid and sucrose) and two feeding deterrent compounds (shikimic acid and palmitic acid) for Gonipterus sp. n. 2. These chemical markers can be applied to tree breeding programmes for the selection of resistant genotypes to reduce damage caused by Gonipterus weevils.
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