Article

Parasitism of the Eucalyptus Weevil, Gonipterus scutellatus Gyllenhal, by the egg parasitoid, Anaphes nitens Girault, in Eucalyptus globulus plantations in southwestern Australia

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Abstract

The Eucalyptus weevil, Gonipterus scutellatus Gyllenhal, is the most serious pest of established Eucalyptus globulus plantations in southwestern Australia where it may have been introduced from its endemic origin in southeastern Australia. This species has been introduced to many countries but has been brought under successful biological control by the introduction of the egg parasitoid, Anaphes nitens Girault, from southeastern Australia. I investigated whether the elevated pest status of G. scutellatus in southwestern Australia is a result of inadequate biological control by quantifying parasitism rates of the pest. Parasitism rates of G. scutellatus egg masses by A. nitens were very low between late winter and mid spring when most oviposition occurs, and a high percentage of parasitised egg masses at these times were incompletely parasitised. Parasitism rates from late spring onwards approached 100%, but fewer egg masses were laid at these times. Low parasitism rates up to mid spring are likely to be due to low numbers of A. nitens at these times because hosts are not available for half the year. In southwestern Australia G. scutellatus has one principal oviposition period in early spring and a second lesser oviposition period in early summer. This short reproductive period appears to be caused by a scarcity of suitable new flushing foliage after spring that is essential for G. scutellatus reproduction. A. nitens did not emerge from eggs of the closely related weevil Oxyops despite eggs of this species being available at a time when G. scutellatus hosts were largely unavailable. Taxonomic difficulties with Gonipterus and possibly Anaphes may also explain the breakdown of biological control in southwestern Australia, and taxonomic revision of these insect groups must be a future research priority.

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... control [17,21,24]. In cold regions, leaf-flushing by eucalyptus trees is inhibited by low temperatures during the winter months, which reduces the number of suitable sites for the females of G. platensis to lay their eggs and consequently causes a decline in the number of hosts available for A. nitens [21,24,25]; this, in turn, leads to a decrease in the populations of A. nitens in winter. ...
... control [17,21,24]. In cold regions, leaf-flushing by eucalyptus trees is inhibited by low temperatures during the winter months, which reduces the number of suitable sites for the females of G. platensis to lay their eggs and consequently causes a decline in the number of hosts available for A. nitens [21,24,25]; this, in turn, leads to a decrease in the populations of A. nitens in winter. At the end of winter/early spring, when G. platensis begins to lay more eggs, A. nitens cannot respond in sufficient numbers and suffers high rates of mortality. ...
... At the end of winter/early spring, when G. platensis begins to lay more eggs, A. nitens cannot respond in sufficient numbers and suffers high rates of mortality. Although the rates of parasitism at the end of the spring may be over 90%, the snout beetle larvae that escape parasitism early in the season have already caused defoliation [17,21,22,24,25]. As successful control has not been achieved with A. nitens in several major eucalyptus-producing regions, classic biological control (CBC) with other natural enemies must be considered. ...
Article
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Forests are a natural resource of great importance for sustainable development. They represent the primary use of Spanish territory and cover 36% of its area. Eucalyptus shrublands are the most productive, particularly on the Cantabrian coast, occupying a total area of 406,566 ha. Since 1991, some of these shrublands have been affected by the eucalyptus snout beetle (Gonipterus platensis), a coleoptera (weevil) from the Curculionidae family that feeds on eucalyptus leaves and produces significant damage. The innovation project of the Supra-regional Operational Health Group on Gonipterus in Eucalyptus was developed (2019–2020) to establish a global approach to the serious problem it causes in Asturias and Galician Eucalyptus stands. A group of experts devised two action protocols to unify the methods and variables measured in the field: a protocol for measuring and estimating damage (degree of defoliation) and a parasitism protocol to establish actions to monitor the degree of parasitism (collection of oothecae, management of the sample, laboratory procedure). In the results, in addition to establishing the sampling protocol, an analysis of the data (from 2017 to spring 2020) provided by the different administrations of the Autonomous Communities studied has been carried out. The data analysis reveals an improvement in the impact of the damage on the Cantabrian coast (29.8% reduction in damage in Galicia and 14.7% in Asturias). In Galicia, the number of adult insects decreased from 2017 to 2019, increasing in the spring (from April to June) of 2020 above the mean values of previous years in that period. The number of larvae in the different larval stages showed similar development in all cases. The mean larvae (in their different stages) and mean oothecae showed a significant decline in the year 2018 compared to the spring of 2017, with an upturn in 2019 and again similar values to 2018 in the spring of 2020. In Asturias, similar mean values of the order of 0.5 insects per plot on dates (May–June) in spring were observed in 2019. While in 2020, a progressive increase could be seen in the mean number of insects throughout March, up to 1.9 insects per plot. Results of research on the biological treatment of parasitisation of oothecae with A.nitens were also collected to adjust the number of oothecae per bag deposited in the field and the number of Anaphes released per ha. Based on the field observations, the appropriate release time was determined to succeed in controlling the Gonipterus population.
... The distribution records of the egg parasitoids emerging from the present study together with previous records [24,29,50,51] indicate that three of the five egg parasitoids of Gonipterus are present throughout the entire distribution range of Gonipterus species on the Australian mainland. Two species, A. nitens and C. damoni were previously recorded from the Australian mainland, but with limited distribution [24,29,51]. ...
... Two species, A. nitens and C. damoni were previously recorded from the Australian mainland, but with limited distribution [24,29,51]. This study presents the first record of A. nitens in Queensland: previously, it was recorded from South Australia, Victoria, New South Wales, Australian Capital Territory, Western Australia and Tasmania [24,50,52]. Our results provide the first record of C. damoni in South Australia, Victoria and New South Wales. ...
... This species has previously been recorded from Queensland, Australian Capital Territory and Tasmania [26,38,51], Euderus sp. was recorded from Victoria, New South Wales and Queensland. Previously, Euderus sp. had been identified from Western Australia and Tasmania [26,38,50]. Despite the three species known to be parasitoids of Gonipterus spp., being present on the Australia mainland and Tasmania, further collections for the development and introduction of biological control agents should be focused on the native distribution of the respective invasive species and consider the local climatic conditions of the target region in comparison to the native range. ...
Article
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Gonipterus species are pests of Eucalyptus plantations worldwide. The egg parasitoid wasp Anaphes nitens is used in many countries for the biological control of Gonipterus spp. Recent taxonomic studies have shown that the three invasive Gonipterus spp., which were previously considered as G. scutellatus, form part of a cryptic species complex. These taxonomic changes have implications for the biological control of Gonipterus spp. The aims of this study were to understand the species composition and distribution of Gonipterus spp. and their egg parasitoids in Australia. Gonipterus spp. adults and egg capsules were collected in south-eastern Australia and Tasmania. Adult Gonipterus were identified using morphology and DNA barcoding. Parasitoids were reared from Gonipterus egg capsules and identified. Thirteen Gonipterus species were collected: twelve species were found on the Australian mainland and one species in Tasmania. These included three described species, four previously recognized but undescribed species, two undescribed species and four unidentified species. Five egg parasitoid species that attack Gonipterus spp. were identified. Anaphes nitens, Centrodora damoni and Euderus sp. were identified on the Australian mainland and A. tasmaniae and A. inexpectatus were identified in Tasmania. The results from this study will contribute to the improvement of Gonipterus biological control in the future.
... As the challenges with Gonipterus continue, a renewed interest has arisen to search for new agents to augment the biocontrol in areas where parasitism by A. nitens is suboptimal and, in light of current taxonomic knowledge, to better understand the trophic relationships among the weevils and their hosts and parasitoids. The existence of a variety of egg and larval parasitoids of Gonipterus has been progressively unveiled (Tooke, 1955;Tribe, 2003;Loch, 2008;Colless, 2012;Valente et al., 2017), and some of the tritrophic relationship between weevils, parasitoids and host trees has been recently investigated (Garcia et al., 2019). ...
... The three species of egg parasitoids found in this study are commonly found in association with Gonipterus (Loch, 2008;Valente et al., 2017;Garcia et al., 2019), but their presence in South East Queensland demonstrates the existence of populations that are likely adapted to subtropical conditions and local weevil species. The most well-known parasitoid of Gonipterus, A. nitens, has only recently been confirmed to occur as far north as Queensland (Schröder, in prep.). ...
... The most well-known parasitoid of Gonipterus, A. nitens, has only recently been confirmed to occur as far north as Queensland (Schröder, in prep.). Furthermore, our study revealed that it also parasitizes egg capsules of Oxyops, in contrast to what had been found in Western Australia (Loch, 2008), although the Oxyops species are likely different. Euderus parasitoids were also found in large numbers in the area and emerged from egg capsules collected on four of the tree species sampled, but these wasps have so far not been explored in depth for their potential use in biocontrol programs and are still in need of taxonomic revision. ...
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.
... Very little research towards understanding the Eucalyptus-Gonipterus-A. nitens interactions was published between the 1950s and 1990s. However, there has been a renewed interest in the pest and its biological control due to Gonipterus population outbreaks during the course of the past two decades (Huber and Prinsloo 1990;Loch 2008;Loch and Floyd 2001;Reis et al. 2012;Cordero Rivera et al. 1999;Valente et al. 2017b;Valente et al. 2004). A significant outcome of this renewed interest has been the discovery that the insect known as G. scutellatus throughout its invasive range represents a complex of cryptic species (Mapondera et al. 2012). ...
... At the time of introduction, the pest was incorrectly identified as C. cupressi and it was later established that P. juniperorum preferentially parasitised C. fresai Blanchard (Hemiptera: Aphididae) rather than C. cupressivora Watson & Voegtlin, within the C. cupressi species complex (Day et al. 2003). In a similar manner, incorrect species identification for the ESB may have contributed to variation in classical biological control of this pest (Howarth 1983;Loch 2008;Mapondera et al. 2012;Stiling 1993). ...
... At high altitudes, where winters are cold and dry, the activity of ESB adults decreases (Tooke 1955). This results in insufficient host material for the parasitoid population to overwinter (Loch 2008;Tooke 1955). In spring, host activity increases ahead of the parasitoid population increase, resulting in outbreak populations of the pest (Reis et al. 2012;Tooke 1955). ...
Article
Full-text available
Gonipterus scutellatus (Coleoptera: Curculionidae), once thought to be a single species, is now known to reside in a complex of at least eight cryptic species. Two of these species (G. platensis and G. pulverulentus) and an undescribed species (Gonipterus sp. n. 2) are invasive pests on five continents. A single population of Anaphes nitens, an egg parasitoid, has been used to control all three species of Gonipterus throughout the invaded range. Limited knowledge regarding the different cryptic species and their diversity significantly impedes efforts to manage the pest complex outside the native range. In this review, we consider the invasion and taxonomic history of the G. scutellatus cryptic species complex and the implications that the cryptic species diversity could have on management strategies. The ecological and biological aspects of these pests that require further research are identified. Strategies that could be used to develop an ecological approach towards managing the G. scutellatus species complex are also suggested.
... So far, classical biological control (CBC) has been the main strategy to control these weevil species, mainly through the egg parasitoid Anaphes nitens (Girault) (Hymenoptera: Mymaridae). However, A. nitens does not successfully control Gonipterus in some regions in Europe, South America, Western Australia and South Africa where Eucalyptus has been planted (Tribe, 2003;Loch, 2008;Mayorga et al., 2013;Valente et al., 2017a). For this reason, new biological control agents that might complement the activity of A. nitens have to be identified. ...
... This is the case in parts of the Iberian Peninsula, where E. globulus plantations occupy an area of about 1.4 million ha and generate high economic value (Ruiz and Lopez, 2010;ICNF, 2013). In Chile, G. platensis is also still a problem in areas with particular climatic conditions (Lanfranco and Dungey, 2001), as is the case in Western Australia, where G. platensis established in 1995 and causes significant damage in eucalypt plantations despite the presence of the parasitoid (Loch, 2008). Climate is probably an important factor in unsuccessful biocontrol, as low parasitism rates usually occur in regions with cold winters, leading to a delay in the development of the parasitoid in spring. ...
... This is thought to be due to its oviposition in late winter, before the egg parasitoid starts its activity. Present field records support the hypothesis that G. platensis tolerates low winter temperatures, which is also evidenced by its ability to oviposit in late winter (Loch, 2008). ...
Article
The study was initiated by the relative failure of the parasitoid Anaphes nitens in controlling the eucalypt weevil Gonipterus platensis on the Iberian Peninsula. Our aim was to gain insight into the community of Gonipterus egg parasitoids occurring in Tasmania. During surveys in 2016 and 2017, adult weevils and egg pods were collected from Eucalyptus trees in Tasmania. The weevils were identified using male genital structure and DNA extracted from hatched larvae. Parasitoids that emerged from the egg pods were identified, and trophic associations of egg parasitoids, weevils and host plants were analyzed. Five species of the Gonipterus scutellatus complex, to which G. platensis belongs, were found, including Gonipterus sp. 2, which is reported for the first time from Tasmania. Molecular analysis corroborated previous phylogenetic studies of this group of species. A sixth species, G. notographus, was also collected. Most species were found to overlap in distribution in Tasmania and, despite being oligophagous, to display selectivity among Eucalyptus species used as hosts: G. platensis and G. pulverulentus were mainly found on E. ovata, Gonipterus sp. 1 on E. nitens and E. globulus and G. notographus on ‘peppermint’ species (E. amygdalina and E. pulchella). Five egg parasitoid species were found associated with these Gonipterus species: Anaphes inexpectatus, A. nitens, A. tasmaniae, Cirrospilus sp. and Euderus sp., with no apparent host specialization. Anaphes nitens, Cirrospilus sp. and Euderus sp. were more frequently found on E. ovata, possibly associated with G. platensis and G. pulverulentus, which were dominant on this host species. Conversely, A. inexpectatus was dominantly found on peppermints (43%), suggesting a main association with G. notographus. Anaphes nitens was found at 23 locations out of 117 and in 2017 was the most abundant parasitoid obtained, with an average 20% parasitism rate, indicating that this species is undergoing a geographical and population expansion since its first report from Tasmania in 2012. These findings contribute to the understanding of the parasitoid-Gonipterus-Eucalyptus trophic relationship and stand to improve future classical biological control programs against G. platensis and other invasive Gonipterus species.
... Below altitudes of 400 m, mean parasitism rates range from 70 to 95% during April, while above 600-700 m, parasitism ranges between 0 and 25% (Valente et al. 2004;Reis et al. 2012). Erratic control of G. platensis by A. nitens has been found to occur in other regions in South Africa (Tooke 1955;Tribe 2005), Spain (Cordero Rivera et al. 1999), southwestern Australia (Loch 2008), and Chile (Gumovsky et al. 2015). A widely accepted explanation is that, whenever foliage flushing by eucalypt trees is inhibited, as occurs during winter periods due to low temperature, G. platensis females are deprived of adequate oviposition sites (Tooke 1955;Tribe 2005;Loch 2008). ...
... Erratic control of G. platensis by A. nitens has been found to occur in other regions in South Africa (Tooke 1955;Tribe 2005), Spain (Cordero Rivera et al. 1999), southwestern Australia (Loch 2008), and Chile (Gumovsky et al. 2015). A widely accepted explanation is that, whenever foliage flushing by eucalypt trees is inhibited, as occurs during winter periods due to low temperature, G. platensis females are deprived of adequate oviposition sites (Tooke 1955;Tribe 2005;Loch 2008). This, in turn, results in long periods of low host availability for A. nitens. ...
... In late winter/early spring, G. platensis numbers rise rapidly but the surviving parasitoid population is unable to respond in adequate numbers. Although late spring parasitism rates are often over 90%, the larvae escaping parasitism early in the season have already caused substantial damage to eucalypt trees (Tooke 1955;Cordero Rivera et al. 1999;Tribe 2005;Loch 2008; Reis et al. 2012). Average maximum temperatures during winter months (MaxTw) below a threshold temperature of 10°C resulted in low parasitism rates of G. platensis by A. nitens during late winter (10.1%), while MaxTw above 11.5°C ...
Article
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The Eucalyptus snout beetle, Gonipterus platensis (Marelli), causes severe damage to eucalypt plantations in several countries, despite the presence of the parasitoid Anaphes nitens (Girault). Climate and/or host–parasitoid mismatch may explain A. nitens shortcomings in some areas in Portugal, Spain, Chile, South Africa, or Australia. Because additional parasitoids may be needed to achieve reliable control of this pest, Anaphes inexpectatus Huber and Prinsloo, retrieved from field surveys conducted in Tasmania (the pest’s native habitat), was selected for pre-release studies in Portugal. Life history traits of A. inexpectatus and A. nitens were compared at six temperatures (5, 10, 15, 20, 25, and 30 °C), including development times, thermal constants, viability, parasitism, and behaviour. Temperatures ranging from 10 to 20 °C were adequate for development, while at 25 and 30 °C, deleterious effects of temperature were detected, particularly in A. nitens. Development thresholds were similar for A. inexpectatus and A. nitens (6.0 and 5.4 °C, respectively), but A. nitens needed 313 degree-days to complete development, while A. inexpectatus needed 263 degree-days. Globally, A. nitens produced more progeny, parasitised more eggs, and lived longer than A. inexpectatus. Net reproductive rates were higher for A. inexpectatus at lower temperatures (10 and 15 °C), and higher for A. nitens at moderate temperatures (20 and 25 °C). In addition, A. inexpectatus evidenced higher tolerance to the highest temperature tested (30 °C). Anaphes inexpectatus is likely to establish under field conditions and may enhance parasitism of G. platensis.
... However, in Gonipterus a preference of the adults to oviposit on leaves of chemically treated plants in the weeks following treatment and the combined damage done by both larvae and adults, mask the true defoliation impact when compared with non-chemically treated plants (Palma and Valente, 2008). The factors responsible for the low efficiency of the parasitoid A. nitens in some regions are still poorly understood, although some studies indicate differences in parasitism rate related to season, or host density (Cordero Rivera et al., 1999;Loch, 2008). In the present study we assess the damage caused by G. platensis and its relationship with the efficiency of the parasitoid, in relation to site climate variables, in particular monthly temperatures and precipitation. ...
... Nevertheless, in regions of Galicia (Spain) and of northern and central Portugal, the damage caused by the weevil is above the level of economic acceptance, despite successive releases of the parasitoid by public and private forest enterprises (Cordero Rivera et al., 1999;Valente et al., 2004). Inefficient rates of parasitism by A. nitens were also recorded in some areas of South Africa (Tribe, 2005) and southwestern Australia (Loch, 2008). Possible reasons for the reduced efficacy of the parasitoid have been suggested, such as microclimatic conditions and fluctuations in the population dynamics of both the host and parasitoid (Cordero Rivera et al., 1999;Santolamazza-Carbone and Fernandez, 2004;Loch, 2008). ...
... Inefficient rates of parasitism by A. nitens were also recorded in some areas of South Africa (Tribe, 2005) and southwestern Australia (Loch, 2008). Possible reasons for the reduced efficacy of the parasitoid have been suggested, such as microclimatic conditions and fluctuations in the population dynamics of both the host and parasitoid (Cordero Rivera et al., 1999;Santolamazza-Carbone and Fernandez, 2004;Loch, 2008). Since A. nitens is highly host specific, it has been suggested that high parasitism rates may lead to a local extinction of the host and consequently to the collapse of the A. nitens population, originating a release of the weevil from the parasitoid in the next generation (Cordero Rivera et al., 1999). ...
... However, in Gonipterus a preference of the adults to oviposit on leaves of chemically treated plants in the weeks following treatment and the combined damage done by both larvae and adults, mask the true defoliation impact when compared with non-chemically treated plants (Palma and Valente, 2008). The factors responsible for the low efficiency of the parasitoid A. nitens in some regions are still poorly understood, although some studies indicate differences in parasitism rate related to season, or host density (Cordero Rivera et al., 1999;Loch, 2008). In the present study we assess the damage caused by G. platensis and its relationship with the efficiency of the parasitoid, in relation to site climate variables, in particular monthly temperatures and precipitation. ...
... Nevertheless, in regions of Galicia (Spain) and of northern and central Portugal, the damage caused by the weevil is above the level of economic acceptance, despite successive releases of the parasitoid by public and private forest enterprises (Cordero Rivera et al., 1999;Valente et al., 2004). Inefficient rates of parasitism by A. nitens were also recorded in some areas of South Africa (Tribe, 2005) and southwestern Australia (Loch, 2008). Possible reasons for the reduced efficacy of the parasitoid have been suggested, such as microclimatic conditions and fluctuations in the population dynamics of both the host and parasitoid (Cordero Rivera et al., 1999;Santolamazza-Carbone and Fernandez, 2004;Loch, 2008). ...
... Inefficient rates of parasitism by A. nitens were also recorded in some areas of South Africa (Tribe, 2005) and southwestern Australia (Loch, 2008). Possible reasons for the reduced efficacy of the parasitoid have been suggested, such as microclimatic conditions and fluctuations in the population dynamics of both the host and parasitoid (Cordero Rivera et al., 1999;Santolamazza-Carbone and Fernandez, 2004;Loch, 2008). Since A. nitens is highly host specific, it has been suggested that high parasitism rates may lead to a local extinction of the host and consequently to the collapse of the A. nitens population, originating a release of the weevil from the parasitoid in the next generation (Cordero Rivera et al., 1999). ...
Article
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Sustainable management of forest plantations and cost-effective control strategies depend on previous estimations of the economic level of damage caused by the pests. The eucalyptus weevil, a key pest of Eucalyptus plantations worldwide, is mainly controlled using classical biological control, using the mymarid egg-parasitoid Anaphes nitens (Girault). Nevertheless, in several temperate regions, the parasitoid fails to reduce the weevil populations to economically sustainable levels. This study attempts to (i) relate the efficiency of the parasitoid with climate variables, (ii) relate the level of damage caused by the weevil with the rate of parasitism, (iii) estimate the implications of weevil damage on wood production. Weevil density, damage caused by defoliation on the upper crown and parasitism rates were monitored in 2007, in 34 Eucalyptus globulus stands. Elevation, temperature and precipitation were assessed by using the Worldclim database. Using historic inventory data, wood production was projected to an age of 10 years, prior to the arrival of the weevil, and compared with current data for the same stands.
... Although A. nitens has been reared from its eggs in WA, the parasitoid is not as effective in controlling the weevil there as it is in the eastern states of Australia. Loch (2008) explored the possible reasons for this breakdown in biological control in WA and suggested that a seasonal mismatch of the life cycles of host and parasitoid was the most likely factor, but genital differences noted between specimens of Eucalyptus Weevil from WA and from south-eastern Australia suggested that uncertainty about the true identity of the weevil (R. Oberprieler pers. obs. ...
... obs. 2007) was likely to confound the situation (Loch 2008). The origin and arrival of Eucalyptus Weevil in WA is unclear. ...
... The results or our study allow correction of at least some of the identifications of the Gonipterus species subjected to recent studies in Australia. All studies of G. 'scutellatus' in WA (Loch & Floyd 2001;Cunningham et al. 2005;Loch 2005Loch , 2006Loch , 2008Loch & Matsuki 2010) refer to G. platensis, while in TAS the main species in the oviposition studies of Clarke et al. (1998) is G. notographus (based on voucher specimens in the ANIC and on host preference), and also G. 'scutellatus' in the study of Dungey and Potts (2003) appears to be G. notographus. Gonipterus 'scutellatus' in Elliott and de Little (1984) probably encompasses all five Gonipterus species known from TAS; the photo of the adult in this publication is of G. pulverulentus. ...
Article
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The Eucalyptus Weevil, generally referred to as Gonipterus scutellatus Gyllenhal, 1833 is a significant pest of Eucalyptus species in Africa, America, Europe and New Zealand. It has recently become a pest of Eucalyptus globulus plantations in Western Australia, despite the presence there of the mymarid egg‐parasitoid Anaphes nitens (Girault). Recent taxonomic study has indicated G. scutellatus to comprise a complex of cryptic species, obscuring the identity of the various pest populations of the weevil in the world. We examined (1) whether the apparent cryptic species identifiable on genital differences have a genetic basis; (2) the distribution of these species; and (3) the origin of the population in Western Australia. We studied specimens from across the distribution range of Eucalyptus Weevil in Australia and obtained sequences of three genes from them: cytochrome oxidase I mtDNA, elongation‐factor 1‐α nuclear DNA and 18s rDNA. The cladogram of COI haplotypes resolved 10 well supported clades fully corresponding with genital‐morphologically distinct species, eight of them constituting a monophyletic G. scutellatus complex. Only four of these species proved to be described, as G. balteatusLea, 1897G. platensis (Marelli, 1926), G. pulverulentusLea, 1897 and G. scutellatus Gyllenhal, 1833. The pest species in the world were found to be G. platensis (New Zealand, America, western Europe), G. pulverulentus (eastern South America) and an undescribed species (Africa, France, Italy). The population of G. platensis in Western Australia showed little genetic variation and is indicated to be a recent introduction from Tasmania. The discrimination of the cryptic species of the G. scutellatus complex enables improvements in the management of the pest species in terms of biological control and plantation practices. Our study highlights the critical importance of proper taxonomic studies underpinning biocontrol programs.
... This egg parasitoid has been reported as effective in many situations (Hanks et al., 2000;Lanfranco & Dungey, 2001;Tooke, 1953). However, in some high altitude areas, experiencing colder winters, the wasp fails to reduce weevil populations below the economic threshold of damage (Echeverri-Molina & Santolamazza-Carbone, 2010;Gumovsky, De, Rothmann, Jaques, & Mayorga, 2015;Loch, 2008;Reis et al., 2012;Tribe, 2005). Consequently, G. ...
... platensis remains a threat to eucalyptus economic viability in many world regions (Echeverri-Molina & Santolamazza-Carbone, 2010; Gumovsky et al., 2015;Loch, 2008;Reis et al., 2012;Tribe, 2005). ...
Article
The eucalyptus weevil, Gonipterus platensis (Coleoptera, Curculionidae), is a major pest of eucalyptus plantations worldwide. To date, no pheromones have been identified for this species, despite their valuable potential as tools in monitoring or control strategies. Here we report the detection and identification of pheromones candidates of G. platensis. The weevil's volatile compounds were collected by solid phase micro extraction (SPME) and monolithic material sorption extraction (MMSE). Using Gas Chromatography coupled to Mass Spectrometry (GC/MS) analysis, eleven insect specific compounds were detected and identified: verbenene, cis‐verbenol, trans‐verbenol, verbenone, 2‐oxo‐1,8‐cineole, 9‐hydroxy‐1,8‐cineole, 2‐α‐hydroxy‐1,8‐cineole, 3‐oxo‐1,8‐cineole, 2‐β‐hydroxy‐1,8‐cineole, 3‐α‐hydroxy‐1,8‐cineole and 7‐hydroxy‐1,8‐cineole. Three of these compounds, verbenene, cis‐verbenol and trans‐verbenol, were shown to be male‐specific. Antennal sensitivity towards ten compounds emitted by G. platensis was detected using Gas Chromatography–Mass Spectrometry/Electroantennographic Detection (GC‐MS/EAD). Extracts from virgin males proved to be attractive to virgin females in olfactometer bioassays. Further behavioural bioassays showed that both virgin females and virgin males were attracted to the male‐specific compound cis‐verbenol and that virgin females were attracted to trans‐verbenol. Verbenone was attractive to mated females. Regarding 2‐α‐hydroxy‐1.8‐cineole and 2‐oxo‐1,8‐cineole, which are produced by both sexes, the alcohol was attractive to virgin males and both the alcohol and the ketone were repellant to mated females. This is, to our knowledge, the first identification of pheromones candidates in Gonipterus spp. and also the first evidence of cineole metabolites acting as semiochemicals.
... Gonipterus platensis populations have been partially or completely controlled in these regions using the CBC agent Anaphes nitens (Girault) (Hymenoptera: Mymaridae), imported from Australia (Valente et al., 2018). Despite the good results obtained with A. nitens, successful control has not been achieved everywhere, especially in some regions of South America (Gumovsky et al., 2015), Western Australia (Loch, 2008), and Southwestern Europe (Cordero-Rivera et al., 1999;Reis et al., 2012;Valente et al., 2018). Different climatic requirements of G. platensis and A. nitens and asynchrony between oviposition by the snout beetle and the parasitoid may explain the insufficient efficacy of A. nitens in those regions (Tribe, 2003;Loch, 2008;Reis et al., 2012). ...
... Despite the good results obtained with A. nitens, successful control has not been achieved everywhere, especially in some regions of South America (Gumovsky et al., 2015), Western Australia (Loch, 2008), and Southwestern Europe (Cordero-Rivera et al., 1999;Reis et al., 2012;Valente et al., 2018). Different climatic requirements of G. platensis and A. nitens and asynchrony between oviposition by the snout beetle and the parasitoid may explain the insufficient efficacy of A. nitens in those regions (Tribe, 2003;Loch, 2008;Reis et al., 2012). In Southwestern Europe, Reis et al. (2012) found that parasitism in early spring decreased along an altitude gradient. ...
Article
The Eucalyptus snout beetle, Gonipterus platensis (Marelli), is an important pest of Eucalyptus globulus Labill. This insect is partially controlled by the egg parasitoid Anaphes nitens (Girault) in many regions, but the introduction of additional natural enemies can potentially increase pest control. In this study, we evaluate intra- and interspecific competitive interactions between the incumbent A. nitens and the new egg parasitoid Anaphes inexpectatus Huber and Prinsloo. The effects of temperature, order of parasitism, number of parasitoid ovipositions, time interval between ovipositions, and host egg age were analysed. Distinct outcomes of competition were found at different temperatures, with benefit to A. inexpectatus at 20 °C. The first species to parasitise generally prevailed over the second, indicating exploitation competition. However, interference competition was also apparent, namely when A. inexpectatus laid multiple eggs, outcompeting A. nitens, and when the first parasitism occurred six days before. In this case, the second species was able to eliminate the first. Anaphes nitens tended to reject eggs parasitised by A. inexpectatus, whereas A. inexpectatus showed no interspecific host discrimination behaviour towards eggs parasitised by A. nitens. Overall, A. nitens parasitised more hosts and is expected to contribute more to pest control, but it was found to be more susceptible to intraspecific competition. Results suggest that A. inexpectatus and A. nitens should be able to coexist, as asymmetric competition was found to depend on temperature. However, A. inexpectatus establishment in the field in areas where A. nitens is already present may be delayed or even prevented due to interspecific competition. As such, the introduction of A. inexpectatus in a classical biological control programme against G. platensis is advised to be carried out by releasing large numbers of parasitoids in consecutive occasions.
... Following the success of this biological control, other countries suffering under Gonipterus imported the parasitoid species from South Africa, but while it proved equally successful in other African countries, it was far less effective in other parts of the world, particularly in Spain [59,60], Portugal [61] and Chile [62]. Also in Western Australia, where Gonipterus weevils had appeared in plantations of Eucalyptus globulus in about 1995, control by A. nitens was patchy and ineffective [63]. The limited success to failure of the biocontrol efforts in these countries was generally ascribed to climatic factors, in particular low temperatures during winter and at higher altitudes, which were thought to exceed the temperature tolerance of the parasitoid but not that of the weevil. ...
... The limited success to failure of the biocontrol efforts in these countries was generally ascribed to climatic factors, in particular low temperatures during winter and at higher altitudes, which were thought to exceed the temperature tolerance of the parasitoid but not that of the weevil. However, Loch [63] raised the possibility that G. scutellatus may be a complex of sibling species and that the identity of the weevil species could play a role in the differential successes of the biocontrol efforts. ...
Article
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Curculionidae are a large mainly herbivorous family of beetles, some of which have become crop pests. Classical biological control has been attempted for about 38 species in 19 genera, and at least moderate success has been achieved in 31 % of cases. Only two weevil species have been considered to be completely controlled by a biological control agent. Success depends upon accurately matching natural enemies with their hosts, and hence taxonomy and phylogeny play a critical role. These factors are discussed and illustrated with two case studies: the introduction of the braconid parasitoid Mictroctonus aethiopoides into New Zealand for biological control of the lucerne pest Sitona discoideus, a case of complex phylogenetic relationships that challenged the prediction of potential non-target hosts, and the use of a mymarid egg parasitoid, Anaphes nitens, to control species of the eucalypt weevil genus Gonipterus, which involves failure to match up parasitoids with the right target amongst a complex of very closely related species. We discuss the increasing importance of molecular methods to support biological control programmes and the essential role of these emerging technologies for improving our understanding of this very large and complex family.
... According to these early studies, Eucalyptus viminalis, Eucalyptus punctata and Eucalyptus globulus are the most susceptible species, with E. viminalis considered the beetle's favourite (Mally 1924;Tooke 1953). In many other literature reviews, E. globulus and E. viminalis are identified as the most preferred host plants of the Eucalyptus Weevil (Millar et al. 1998;Hanks et al. 2000;Loch 2008). However, the host preference of the weevil is not exactly the same in different countries (Table 1) and a marked difference in host range was found in a native population of G. scutellatus in Tasmania by Clarke et al. (1998), who recorded oviposition to preferably take place on three "peppermint" species of Eucalyptus (Eucalyptus pulchella, Eucalyptus tenuiramis and Eucalyptus amygdalina) while E. globulus and E. viminalis were the least-favoured oviposition hosts. ...
... As already suspected by Loch (2008), it is now known that G. "scutellatus" actually comprises a complex of at least ten very similar (largely cryptic) species that have been confused in all previous literature. A revision of this complex and clarification of the taxonomy and nomenclature of its various species (Oberprieler, in preparation) as well as a molecular analysis of the complex (Mapondera et al., in preparation) are in progress. ...
Article
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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
... associated with damage caused by G. platensis amounted to €648 M in the last 20 years (Valente et al., 2018). The larval parasitoid Anaphens nitens Girault (Hymenoptera: Mymaridae) has been used to control G. platensis across most of its distribution area (Valente et al., 2017b), but it has failed to provide satisfactory results in several regions (Cordero Rivera et al., 1999;Gumovsky et al., 2015;Loch, 2008;Reis et al., 2012;Tooke, 1955;Tribe, 2005;Valente et al., 2004). However, despite the severe consequences of Gonipterus spp. in Eucalyptus plantations, few studies have addressed (e.g. ...
Article
Plantations of Eucalyptus species have been widely used in Spain to meet the high demand for wood given their rapid growth and high wood production capacity. Defoliation induced by the invasive eucalypt weevil (Gonipterus platensis (Marelli)), however, has been causing significant economic damage to Spanish Eucalyptus spp. plantations since the 1990s. G. platensis is native to Tasmania, Australia, where populations are controlled by natural enemies including the egg parasitoid Anaphes nitens Girault. In this study, spatio-temporal Universal Kriging was applied to examine the dynamics of defoliation damage caused by G. platensis in Spanish Eucalyptus spp. plantations and to identify the main factors associated with the presence and spread of the pest. The data set combines the Spanish national plots belonging to the network of the European transnational survey of forest condition in Europe (ICP Forest Level I, 16 × 16 km grid) along with regional plots, measured using similar field protocols, in which Eucalyptus spp. are present. A total of 264 Eucalyptus plots were included in the study, G. platensis being present in 167 of these plots at some time during the observed period (2005–2020). Our results show that defoliation damage > 0% and defoliation damage > 5% caused by G. platensis increased over the period 2005–2010 and then decreased between 2010 and 2020. Defoliation damage > 15% incidence steadily decreased from 2005 to 2015, but showed an upturn in 2020. Stands belonging to the Atlantic region are more affected by this pest (76% of the Atlantic sampling plots affected versus just 4% of the Mediterranean plots). The species Eucalyptus globulus Labill. and monospecific stands, as well as spring precipitation of the current year were found to be positively associated with the incidence of G. platensis whereas the relationship with summer temperature of the previous year was negative. Finally, maps showing the degree of incidence over time have been produced to support decision-making for pest prevention and control. This study puts forward a methodology which allows the spread of this pest to be better understood and simulated, thus facilitating risk prevention.
... From South Africa the parasitoid was imported to various other countries where the weevil had reached pest proportions, with mostly also good but not as spectacular results. In particular, the wasp proved ineffective in controlling the weevil in colder areas (Cordero Rivera et al. 1999;Tribe 2003Tribe , 2005Loch 2008;Reis et al. 2012). Recent studies showing that G. "scutella tus" comprises a complex of mostly cryptic species and that three different species of Gonipterus have established in the world outside of Australia (Mapondera et al. 2012) indicate that only the species in Africa, France and Italy is a natural host for A. nitens and that native Tasmanian species of Anaphes appear better suited to control G. platen sis in Western Australia, Chile, Portugal, Spain and other areas where it now occurs (Valente et al. 2010). ...
... obs.) and other studies in the Iberian Peninsula (Cordero-Rivera et al., 1999;Valente et al., 2004;Santolamazza-Carbone et al., 2006;Branco et al., 2016). Different climatic requirements of the parasitoid and its host, and a time-lag between A. nitens and oviposition by G. platensis have been put forward to explain a lower effectiveness of biological control in spring (Tribe, 2003;Loch, 2008). In our study, however, both first and second generation abundance models demonstrated a significant effect of elevation, similar in magnitude, which should mean that biological control by A. nitens was equally ineffective on both G. platensis annual generations. ...
Article
The weevil Gonipterus platensis is among the most important eucalypt (Eucalyptus spp.) pest species worldwide. In Portugal, weevil-induced damage has great economic significance and efforts are being taken to find adequate alternatives to the biological control of this defoliator by its parasitoid Anaphes nitens, which is ineffective at altitudes above 400 m. With the aim of improving current knowledge on the ecology of G. platensis, we evaluated its interactions with local and landscape factors through the application of generalized linear mixed models for (1) the probability of weevil occurrence in sampling points, and (2) the relative abundance of each of its two annual generations on eucalypt trees. Our models confirmed the significant positive effect of elevation, here found to come off just above 360 m a.s.l., on both the occurrence and the abundance of G. platensis. Moreover, our results denoted that stand-level variables can likewise affect this pest. Points located more than 400 m inside the stands and, to a lesser extent, those comprising smaller (yet mature) eucalypt trees and where trees of other species were absent, showed an increased probability of G. platensis occurrence. Concordantly, significantly higher abundances of both weevil generations were observed on 3-8 years-old eucalypt trees. In addition, there was a negative effect of coppiced stands on G. platensis abundance which was only significant for the first annual generation and probably was related with weevil's recent colonization of stands ravaged by wildfires two years before our field surveys. Weevil populations were not influenced by the density of stand canopy, neither by understory structure and composition, nor by bare soil cover, hence it is not expected that thinning, shrub removal and soil scarification practices can affect G. platensis attacks in eucalypt stands. Overall, our study provides key knowledge on the ecology of G. platensis and its response to local and landscape features, paving the way for enhanced management of eucalypt plantations.
... Then the introduction of the Australian egg parasitoids, A. nitens and A. inexpectatus to control G. platensis could be safe. It is expected that these parasitoids show preference for the eggs that are so speci c to the species of the genus Gonipterus (Loch 2008). E orts for its importation should be started in a short time. ...
... Then the introduction of the Australian egg parasitoids, A. nitens and A. inexpectatus to control G. platensis could be safe. It is expected that these parasitoids show preference for the eggs that are so speci c to the species of the genus Gonipterus (Loch 2008). E orts for its importation should be started in a short time. ...
... Several studies have highlighted the selective nature of G. scutellatus, whereby certain eucalyptus species are more preferred than others. [53][54][55][56] For example, Fuentes et al. 56 found that Eucalyptus camaldulensis was more susceptible to G. scutellatus defoliation than Eucalyptus robusta or Eucalyptus globulus. In our case, the eucalyptus species found toward the southern parts of the predictive map were Eucalyptus grandis and toward the northern parts were Eucalyptus dunni. ...
Article
Defoliation induced by the weevil Gonipterus scutellatus is causing significant damage to South Africas eucalyptus plantations. Therefore, the ability of remote sensing to detect and map G. scutellatus defoliation is essential for monitoring the spread of the weevil so that precautionary measures are set in place. In our study, an integrated approach using image texture in various processing combinations and an artificial neural network (ANN) were developed to detect and map G. scutellatus induced vegetation defoliation. A 0.5-m WorldView-2 pan-sharpened image was used to compute texture parameters from the gray-level occurrence matrix and gray-level co-occurrence matrix, using optimal moving windows for specific levels of G. scutellatus induced vegetation defoliation. In order to improve the accuracy of detecting and mapping G. scutellatus induced vegetation defoliation, a method involving a three-band texture processing combination was proposed and tested. Using a sequential forward selection algorithm allowed for the selection of optimal texture combinations, which were subsequently input into a backpropagation ANN. The results showed an improvement in detecting vegetation defoliation using single texture bands [R ² =0.82, root mean square error (RMSE) = 0.95 (1.82% of the mean measured defoliation)] when compared to single spectral reflectance bands [R ² =0.60, RMSE = 1.79 (3.43% of the mean measured defoliation)], two-band spectral reflectance combination model [R ² =0.74, RMSE = 1.48 (2.83% of the mean measured defoliation)], and the three-band spectral reflectance combination model [R ² =0.80, RMSE = 1.35 (2.59% of the mean measured defoliation)]. Further improvements were obtained using the two-band texture combination model [R ² =0.85, RMSE = 1.05 (2.01% of the mean measured defoliation)] and the most promising result was obtained using the proposed three-band texture combination model [R ² =0.90, RMSE = 0.85 (1.63% of the mean measured defoliation)]. Overall, our study highlights the potential of image texture combinations in improving the detection and mapping of vegetation defoliation. © 2019 Society of Photo-Optical Instrumentation Engineers (SPIE).
... G. scutellatus can cause severe damage to Eucalyptus trees mainly outside its native range, in which a rich community of predators and parasitoids has been shown to be able to control weevil infestations (TOOKE, 1953;LOCH and FLOYD, 2001;LOCH, 2008;LOCH and MATSUKI, 2010). In newly introduced areas, a different susceptibility of Eucalyptus species to G. scutellatus infestations and development has been observed (CORDERO RIVERA and SANTOLAMAZZA CARBONE, 2000;NEWETE et al., 2011). ...
Article
Full-text available
In Sardinia (Italy), Eucalyptus plantations cover approximately 23,000 hectares, above all in the southern part of the island. There is a complex of phytophagous insect pests that is threatening the health status of Eucalyptus trees. The most recent invasions include the sap-suckers, Glycaspis brimblecombei, Blastopsylla occidentalis, and the bronze bug, Thaumastocoris peregrinus. Other pest species have also been reported, including the gall wasps, Ophelimus maskelli and Leptocybe invasa, the longhorn beetles, Phoracantha semipunctata and P. recurva, and the weevils, Gonipterus scutellatus and Polydrusus (= Metallites) parallelus. Defoliation caused by the gypsy moth, Lymantria dispar, have also been frequently observed in various Eucalyptus-planted areas of Sardinia.
... It was also introduced in New Zealand, North and South America, and Europe (Arzone and Vidano, 1978;Hanks et al., 2000;Tooke, 1955). Good results were obtained with A. nitens in many countries, but complete success was not always achieved, especially in the case of G. platensis in some regions in South America, Western Australia, and Southwestern Europe (Loch, 2008;Mapondera et al., 2012;Reis et al., 2012;Valente et al., 2004). ...
Article
Despite the importance of invasive pests, few studies address the costs and benefits of the strategies used to control them. The present work assesses the economic impact of the Eucalyptus snout beetle, Gonipterus platensis, and the benefits resulting from its biological control with Anaphes nitens in Portugal, over a 20-year period. Comparisons were made between the real situation (with A. nitens) and three scenarios without biological control: 1) replacement of Eucalyptus globulus by resistant eucalypts; 2) insecticide use; and 3) offset of yield losses by imported wood. A cost-benefit analysis was performed to evaluate a programme that aimed to accelerate A. nitens establishment. Although A. nitens provides adequate pest control in several regions, 46% of the area planted with eucalypts is affected by the beetle, causing wood losses of 648 M euros over 20 years. Losses in the three hypothetical scenarios were estimated at 2451 M-7164 M euros, resulting in benefits from biological control of 1803 M–6516 M euros, despite the fact that only partial success was achieved. Anticipating biological control by just one, two, or three years resulted in benefit-cost ratios of 67, 190, and 347, respectively. Because nonmarket values were not accounted for, these figures are likely underestimated.
... (Hymenoptera: Proctotrupidae) and Anagonia sp. (Diptera: Tachinidae) (Loch, 2008). In all the countries colonised by the pest, damage has been significantly reduced by means of the biological control exerted by A. nitens Tooke, 1955;Cordero Rivera et al., 1999;Hanks et al., 2000). ...
Article
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Abstract The Panel on Plant health performed a pest categorisation of the Australian Eucalyptus snout‐beetle Gonipterus scutellatus (Coleoptera: Curculionidae), for the EU. G. scutellatus should be referred as the G. scutellatus species complex because it includes several cryptic species. A complete nomenclature of the species present in the EU is still pending. It is a quarantine pest listed in Annex IIB of Council Directive 2000/29/EC. Protected zones are in place in Greece and Portugal (Azores). In the EU, it has been found in Italy, France, Spain and Portugal. It only consumes Eucalyptus species leaves. The main pathways of spread are the trade of Eucalyptus timber, hitchhiking in various commodities, trade of apple fruit as well as of plants for planting or plant parts. Spread by flight is also possible. The climate of the EU protected zones is similar to that of the Member States (MS) where the G. scutellatus complex is established, and the pest's main host plants are present. The damaged trees suffer die‐back and the development of epicormics shoots. Severe attacks may provoke massive amounts of tree death. Biological control by using the egg parasitoid wasp Anaphes nitens is the most effective control measure. Some species within the G. scutellatus complex are not yet present in the EU (including G. scutellatus sensu stricto) and might therefore be considered as potential union quarantine pests for the EU territory. At least two species within the G. scutellatus complex (most likely G. platensis and Gonipterus species no. 2) meet the criteria assessed by EFSA for consideration as potential protected zone quarantine pests for the territory of the protected zones: Greece and Portugal (Azores). The criteria for considering the G. scutellatus complex as a potential regulated non‐quarantine pest for the EU are not met since plants for planting are not the main pathway.
... Previous reports of Euderus parasitism of Curculionidae species include Cylindrocopturus eatoni Buchanan and Ceutorhynchus rapae (Gyllenhal) (Yoshimoto 1971); Ceutorhynchus obstrictus (Marsham) (Dosdall et al. 2009;Mason et al. 2011); Cylas formicarius (F.) (Jansson & Lecrone 1991), and Gonipterus scutellatus Gyllenhal (Loch 2008). Similarly, Eurydinoteloides species attack various Curculionidae species, including Eutinobothrus brasiliensis (Hambleton) (Hambleton & Sauer 1938;Monte 1944;Sauer 1946), species of Chalcodermus Schönherr, and 10 additional genera (Noyes 2015). ...
Article
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Chalcodemus bicolor Fiedler (Coleoptera: Curculionidae) is the most recent pest in Brazilian Eucalyptus (Myrtaceae) plantations. Sampling in 2011 for parasitoids of this weevil recovered 4 Hymenoptera species, 3 in the genus Euderus (Eulophidae), comprising 98.4% of specimens, and Eurydinoteloides sp. (Pteromalidae). This is the first report of natural enemies of C. bicolor.
... In fact, some studies have shown that their emergence correlates with preceding peaks of abundance of cicadellids in the field (Huber, 1986;Albajes et al., 2009). They have been documented as biological pest control agents (Krugner et al., 2008;Loch, 2008), making them suitable candidates to be used in NTA risk assessment. ...
Article
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The cultivation of Cry1Ab-expressing genetically modified MON810 (Bt maize) has led to public concern in Europe, regarding its impact on non-target arthropods (NTAs). We have assessed the potential effects of DKC 6451 YG (MON810) maize on canopy NTAs in a farm-scale study performed in Central Spain during three years. The study focused on hemipteran herbivores (leafhoppers and planthoppers) and hymenopteran parasitic wasps (mymarids) collected by yellow sticky traps, which accounted for 72% of the total number of insects studied. The dynamics and abundance of these groups varied among years, but no significant differences were found between Bt and non-Bt maize, indicating that Bt maize had no negative effect on these taxa. Nonetheless, the Cry1Ab toxin was detected in two different arthropods collected from Bt maize foliage, the cicadellids Zyginidia scutellaris and Empoasca spp. A retrospective power analysis on the arthropod abundance data for our field trials has determined that Z. scutellaris and the family Mymaridae have high capacity to detect differences between the Bt maize and its isogenic counterpart. The use of these canopy NTAs as surrogates for assessing environmental impacts of Bt maize is discussed. This article is protected by copyright. All rights reserved
... Since its fi rst introduction, A. nitens has been the sole organism used for the control of Gonipterus spp. Despite the enormous success of A. nitens worldwide, in some particular areas, this biocontrol strategy was ineffective, such as in some regions in South Africa (Tribe 2005 ), southwestern Australia (Loch 2008 ), South America (Sanches 2000 ) and in cold regions in the Iberian Peninsula (Reis et al. 2012 ). In these areas parasitism rates are variable, usually below 40 % during late winter and early spring. ...
Chapter
In this chapter we concentrate on the main invasive species which feed on the foliage, by consuming leaves or inducing galls, and which affect both native and non-native tree species. We provide details on their biology, invasion routes, host tree species, damage to native and non-native trees and control strategies.
... Adults and larvae of this species feed on new developing Eucalyptus leaves, buds and shoots, mainly on E. globulus. A female lays around 800 eggs in groups of 4-16 laid on developing shoots and leaves, and the mass is protected by a capsule made of faeces (Loch 2008). Both males and females can live for more than one year. ...
Article
Full-text available
Entedon magnificus (Girault & Dodd) (Hymenoptera: Eulophidae, Entedoninae) is recorded as a gregarious larval endoparasitoid of Gonipterus weevils (Coleoptera: Curculionidae), significant pests of Eucalyptus trees. Entedon magnificus is re-described and illustrated based on females and males from Australia and Tasmania.
... Phoracanta semipunctata (eucalyptus longhorned borer) attacks drought-stressed trees in E. globulus plantations in the Mediterranean area and has been reported to have spread into California [38]. Gonipterus scutellatus (eucalyptus snout beetle) has been shown to defoliate commercial species in Australia, South Africa, and Spain [39]. ...
Article
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Eucalyptus plantations have been employed as a source of short fiber for papermaking for more than 40 years. The development in genetic improvement and clonal programs has produced fast growing, increased fiber volume, improved density plantations which have resulted in eucalypts becoming the most widely used short fibers in the world. High productivity and short rotation times in conjunction with the uniformity and improved wood quality of clonal plantations have attracted private industry investment in eucalypt plantations. Currently, only a handful of species or hybrids are employed in plantation efforts. Many more species are being evaluated to either enhance fiber properties or expand the range of eucalypt plantations. Eucalyptus plantations are frequently planted on non-forested land and may be employed, in part, as a means of conserving native forests while allowing the production of high quality fiber for economic uses. Finally, eucalypt plantations are capable of providing significant carbon sinks which may be employed to help offset the carbon released from burning of fossil fuels. The development and expansion of eucalypt plantations represents a substantial revolution in pulp and paper manufacturing.
... Dado que o factor mais importante à dinâmica das populações destes fitófagos, nas regiões onde foram introduzidos, é a ausência de inimigos naturais, uma vez que se encontram afastadas do complexo de agentes bióticos a que estão sujeitas no seu ambiente natural, a luta biológica clássica tem sido a solução mais promissora e sustentável a longo prazo. De facto, o sucesso no controlo das pragas dos eucaliptos tem sido, em larga escala, obtido com projectos de luta biológica clássica, do qual o exemplo mais conhecido é o da introdução do parasitóide óofago Anaphes nitens (Hymenoptera: Mymaridae) introduzido em várias regiões do globo para o controlo do gorgulho do eucalipto, Gonipterus scutellatus (e.g.Hanks et al., 2000;Loch, 2008;Protasov et al., 2007b;Sanches, 2000). No entanto, registam-se com frequência, casos de insucesso na luta biológica. ...
... Adults and larvae of this species feed on new developing Eucalyptus leaves, buds and shoots, mainly on E. globulus. A female lays around 800 eggs in groups of 4–16 laid on developing shoots and leaves, and the mass is protected by a capsule made of faeces (Loch 2008). Both males and females can live for more than one year. ...
Article
Entedon magnificus (Girault & Dodd) (Hymenoptera: Eulophidae, Entedoninae) is recorded as a gregarious larval endoparasitoid of Gonipterus weevils (Coleoptera: Curculionidae), significant pests of Eucalyptus trees. Entedon magnificus is re-described and illustrated based on females and males from Australia and Tasmania.
... From South Africa the parasitoid was imported to various other countries where the weevil had reached pest proportions, with mostly also good but not as spectacular results. In particular, the wasp proved ineffective in controlling the weevil in colder areas (Cordero Rivera et al. 1999;Tribe 2003Tribe , 2005Loch 2008;Reis et al. 2012). Recent studies showing that G. "scutella tus" comprises a complex of mostly cryptic species and that three different species of Gonipterus have established in the world outside of Australia (Mapondera et al. 2012) indicate that only the species in Africa, France and Italy is a natural host for A. nitens and that native Tasmanian species of Anaphes appear better suited to control G. platen sis in Western Australia, Chile, Portugal, Spain and other areas where it now occurs (Valente et al. 2010). ...
Chapter
Oberprieler R.G., Caldara R. & Skuhrovec J. (2014) 29.13. Bagoini Thomson, 1859; Gonipterini Lacordaire, 1863; Hyperini Marseul, 1863, pp. In . (R. A. B. Leschen and R. G. Beutel, editors). De Gruyter, Göttingen, 675 pp.
... Gonipterus scutellatus Gyllenhall, 1833 (Coleoptera: Curculionidae) is considered to be an Eucalyptus genus specialist, with a marked preference for some species, depending on the different countries where it has spread (CORDERO RIVERA & SANTOLAMAZZA CARBONE, 2000). It comes from Southeastern Australia and lives on several species, particularly E. globulus and E. viminalis Labill., the manna gum (LOCH, 2008). Both adults and larvae feed on the leaves of host trees, but the larval stages cause the most important damages. ...
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Alien insects on Eucalytpus spp.: an australian biocenosis in Tuscany. Despite the diffusion of eucalypts in Italy, the community of insects hosted by these trees is scantily studied, while information about the presence of these pests is crucial for their potential threats to economic activities. This study aims at investigating and evaluating the status of Australian insects hosted by eucalypts in Tuscany (Central Italy). We found six established species and, among them, two species recently discovered in the study area were noteworthy for their potential impacts and diffusion: Gonipterus scutellatus complex and Glycaspis brimblecombei. We provided a distribution map on Tuscan coast for both these species and revised data on biology and presence of these and other alien insects Eucalyptus-linked species.
... Within Australia, we would not expect classical biological control to be effective against a native pest unless the pest has extended its range beyond that of its natural enemies, such as the spread of eucalyptus weevil Gonipterus spp. and the chrysomelid P. m-fuscum into Western Australian E. globulus plantations (Loch, 2008;M. Matsuki, personal communication). ...
Article
In Australia, eucalypt plantations require management to prevent economic damage by native chrysomelid leaf beetles, generally by aerially spraying a broad-spectrum insecticide. These beetles also pose a serious threat to plantations in other countries.Various alternatives, both ‘landscape’ and ‘control’ options, for managing leaf beetles were reviewed and evaluated by a panel of experts. Options were scored on effectiveness, feasibility for use, impact on the environment, perceived social acceptability (including by certification bodies) and perceived cost.None of the options were scored as well as broad-spectrum insecticide for effectiveness, feasibility and perceived cost, although virtually all of the other options scored better for environmental and social outcomes. The highest ranked options were the ‘landscape’ option of tree improvement to reduce susceptibility to insect attack, and the ‘control’ option of attract-and-kill traps. The next three ranks were two ‘landscape’ options aimed at enhancing the effectiveness of natural enemy populations by conserving their overwintering sites and their alternative food and hosts, and then silvicultural management. The best strategy for an Integrated Pest Management programme would be a combination of ‘landscape’ options to reduce the frequency of pest outbreaks and, if outbreaks occur, spraying with biological insecticides until attract-and-kill traps become available, possibly in combination with repellent sprays in a push–pull strategy. If control measures fail to prevent damaging defoliation, plantations could be fertilized to encourage recovery. Because most of the alternative options are not yet available, many research directions were identified, with the highest priorities being to develop plantation stock that is less susceptible to defoliation and to develop attractants for leaf beetles.
... The Eucalyptus snout-beetle Gonipterus scutellatus Gyllenhal (Coleoptera: Curculionidae), native to south-eastern Australia, is one of the most important defoliators of Eucalyptus plantations worldwide (Tooke 1955;Arzone 1976;Cordero-Rivera et al. 1999;Hanks et al. 2000;Lanfranco and Dungey 2001;Loch 2008). Currently, it is present in four continents and twenty-two countries, where eucalypts are cultivated for commercial and ornamental purposes (OEPP/EPPO 2005). ...
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Toxicity by contact and by ingestion of lufenuron, flufenoxuron, lambda (λ)-cyhalothrin, cypermethrin, thiamethoxam and five entomopathogenic insecticides (three formulations of Beauveria bassiana, a compound containing spores of Metarhizium anisopliae var. acridum, and a mixture of Brevibacillus laterosporus, Bacillus licheniformis and Bacillus chitinosporus) were evaluated on adults of the Eucalyptus snout-beetle Gonipterus scutellatus Gyllenhal (Coleoptera: Curculionidae) under laboratory conditions. By contact, entomopathogenic fungus B. bassiana EC and the pyrethroid λ-cyhalothrin exhibited the highest efficiency, achieving 100 and 97.5% mortality, respectively. By ingestion, the highest mortality was obtained by B. bassiana EC (100%) and thiamethoxam (95%). Flufenoxuron and lufenuron, bacteria mixture and M. anisopliae showed a weak toxicity. Furthermore, we found a sex-biased mortality, being males more affected. Due to the good performance and low risk to humans and environment, B. bassiana EC (strain PPRI 5339) appears to be the most promising product to promote an IPM programme in South Africa. Keywords Beauveria bassiana - Gonipterus scutellatus -IGRs- Metarhizium anisopliae -Neonicotinoid-Pyrethroid
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The efficiency of local augmentation releases of the egg parasitoid Anaphes nitens to control the Eucalyptus snout‐beetle Gonipterus platensis was tested in Eucalyptus globulus plantations in Galicia (NW Spain). On May–June 2006, at two localities of Pontevedra province, the release of host egg capsules parasitized by A. nitens at a potential rate of 300 adults/ha was compared with a release density of 900 adults/ha, and a control group of eucalypts not subjected to augmentation. Parasitism rate after 1–2 weeks did not significantly increase over the control plots at both localities. The high release rate did not ensure a higher crop protection and therefore could be not economically justified. On March–April 2017, at four localities of Pontevedra province, the test was replicated by releasing 300 parasitoids/ha. Parasitism level did significantly increase over the control just in one locality. Augmentation of A. nitens at small scale generally failed to achieve a higher protection from the pest, possibly due to the large extension of the E. globulus plantations, the magnitude of the G. platensis population and the fluctuations of the established parasitoid population, whose density is in turn affected by host egg availability and density‐dependent dispersal.
Article
Classical biological control is a valuable tool against invasive pests, but concerns about non-target effects requires risk assessment studies. Potential non-target effects of Anaphes inexpectatus Huber and Prinsloo (Hymenoptera: Mymaridae) were assessed for a classical biological control programme against the Eucalyptus snout beetle, Gonipterus platensis (Marelli) (Coleoptera: Curculionidae). No-choice tests were conducted with 17 non-target species to assess host specificity, including 11 curculionids. In behavioural observations, A. inexpectatus showed no interest in any of the non-target species, but two weevil species were parasitised within five days of exposure, although at significantly lower rates than G. platensis. In choice tests, only one non-target, Hypera postica (Gyllenhal) (Coleoptera: Curculionidae), was parasitised, at a rate of 0.6%, while 50.0% of G. platensis eggs were parasitised. Based on the host specificity test results and the potential host fauna found in the target area, the likelihood of non-target effects resulting from the release of A. inexpectatus is considered to be negligible.
Chapter
The Mediterranean forest regions of Australia predominantly comprise native mallee scrub, eucalypt woodlands, exotic Pinus plantations, and commercial eucalypt plantations. Native forests have, so far, remained largely free of invasive exotic insects. The exotic pines, however, have five well-established and significant invasive pest insects: the bark beetles Ips grandicollis, Hylastes ater, and Hylurgus ligniperda (Coleoptera: Curculiondae), Monterey pine aphid, Essigella californica (Hemiptera: Aphididae), and Sirex woodwasp, Sirex noctilio (Hymenoptera: Siricidae), with the latter not yet present in Western Australia (WA). The exotic giant pine scale, Marchalina hellenica (Hemiptera: Margarodidae), was recently detected on pines in Adelaide and Melbourne and is under an eradication program. Many of the established pest species have had classical biological control programs implemented. European house borer, Hylotrupes bajulus (Coleoptera: Cerambycidae), a pest of untreated softwood, is established in areas around Perth, WA, and has been found in dead and live trees, as well as untreated timber. African black beetle, Heteronychus arator (Coleoptera: Scarabaeidae) is a major exotic agricultural and forestry pest in wetter parts of the Mediterranean forest regions in WA, where it was first recorded in 1938. Several other exotic polyphagous horticultural pests are occasionally associated with eucalypts. Australia is the origin of major insect pests on Eucalyptus species grown in Mediterranean regions across the globe. However, populations of these insects are generally effectively controlled by native species of natural enemies in Australia. At least five species endemic to eastern Australia, Gonipterus platensis and G. sp. nov. 2, (Coleoptera: Curculionidae), Paropsisterna m-fuscum (Coleoptera: Chrysomelidae), Phylacteophaga froggatti (Hymenoptera: Pergidae) and Cardiapsina fiscella (Hempitera: Psyllidae), have been introduced to Mediterranean regions of WA, where they initially caused extensive and severe damage to plantations of introduced eucalypt species (predominantly E. globulus) in the region. However, the level and extent of damage gradually decreased, and it has been hypothesised that improved control by endemic natural enemies has occurred.
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Damage from Ecalyptus weevil in the North-West of Spain. Presentation for the course SFR 457 (University of Maine) during the autumn term of 2014. The author was an exchange student in the UM during that time.
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An entomological overview of the eucalypt plantation programme being carried out by the Forestry Commission of New South Wales is presented. Some of the insect pests known to damage eucalypt forests and plantations in New South Wales are listed and discussed.
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In March 1994, Gonipterus scutellatus Gyllenhal, an Australian weevil that feeds on foliage of eucalypts, was discovered in Ventura County, CA. By the time of its discovery, the weevil was defoliating eucalypt trees in citrus orchard windrows. We imported, reared, and released a parasitoid of the weevil's eggs, Anaphes nitens Siscaro (Hymenoptera: Mymaridae). A. nitens was firmly established in several southern California counties by mid-1997 and was spreading in tandem with its host. The wasp has proven to be effective in suppressing weevil populations, killing >95% of weevil eggs, except possibly in areas where insecticides are applied to manage pests of field crops. A. nitens appears to be a promising biological control agent for G. scutellatus in California.
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  Laboratory experiments and field surveys were carried out to study the thermal requirements and phenology of the Eucalyptus snout beetle Gonipterus scutellatus (Curculionidae) and its parasitoid, Anaphes nitens (Mymaridae). Developmental times were recorded for G. scutellatus life stages: egg to first instar larva, first instar to pre-pupal larva, prepupae to adults and the complete life cycle. Experiments were performed in temperature-controlled chambers maintained at 10, 15, 20, 25 and 30°C with a photoperiod of 11 : 13 h of light : darkness and 50–60% RH. To calculate the minimum threshold temperature of the parasitoid, parasitized egg capsules were kept under similar conditions. During 1998 and 1999 we studied the phenology and the day-degree (DD) accumulation of G. scutellatus and its parasitoid in plots of Eucalyptus globulus at six different sites in NW Spain. Every 2 weeks, the numbers of snout beetle adults and egg capsules were counted in each plot. The rate of parasitism was estimated by collecting 90 egg capsules from each plot on each sampling date. We recorded the temperatures in each plot to test whether differences in temperature alone could account for the phenology of this snout beetle. To complete a full life cycle from egg to adult, the weevil required a mean of 1119.83 ± 20.59 DD above a base temperature of 6.11°C. The parasitoid had a base temperature of 5.09°C and needed 318.16 DD to complete a life cycle. Our model indicated that three generations of snout beetle could develop each year, corresponding to peaks of snout beetle numbers in the field in March–April, June–July and November. In some years only one generation of G. scutellatus was recorded due probably to the effectiveness of the parasitoid. Differences in numbers of adults and egg capsule were recorded between neighbouring ‘coastal plots’ and between neighbouring ‘inland plots’. Hence, climate alone does not appear to explain the phenology of G. scutellatus.
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We investigated host finding and host discrimination ability in Anaphes nitens, a solitary egg parasitoid that attacks a gregarious host, the egg capsules of the Eucalyptus snout-beetle, Gonipterus scutellatus. In a first experiment, females were assigned to three treatments: no experience, one experience on an unparasitized egg capsule or one experience on a parasitized egg capsule. We combined this variable with three types of hosts: unparasitized, previously parasitized by the experimental female, or parasitized by conspecifics. Females were observed in a no-choice test, and results indicate that: (1) naive females can discriminate but do not refrain from superparasitism, (2) previous experience and the type of egg capsule affect host acceptance and visit duration, and (3) there is no evidence of self-discrimination. The acceptance of parasitized hosts decreased from 90% for the inexperienced females at their first encounter with the host, to 45% for the experienced females, and visit duration from 17.2 to 9.2 min. In a second experiment, a choice test was performed to assess A. nitens preference towards hosts of different age. Females oviposited preferentially in very young hosts. A field experiment tested the ability to find new hosts within the window of vulnerability of the egg capsules, by manipulation of the time that hosts were exposed to parasitism. Results showed that parasitoids need one day to discover the hosts and that parasitism does not increase after three days. We conclude that A. nitens biocontrol success is due to its ability to find fresh hosts, and to its discrimination ability, even if the female is inexperienced.
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Aphelinidae are all insect parasitoids, and most species are associated with nymphal stages of Homoptera: Sternorrhyncha, either as primary parasitoids or hyperparasitoids. The occurrence of egg parasitism in aphelinids has been recorded in eight of the 38 valid genera and these records are reviewed; it is particularly common in the genus Centrodora, which is shown to be the most polyphagous in the family. One species, C. darwini (Girault), is given special attention because of its occurrence in three recent surveys for biological control agents of crop pests. It is briefly redescribed, diagnosed, and shown to be the most polyphagous aphelinid known. A checklist of Australian Centrodora spp. is given, including the new combination Centrodora grotiusi (Girault) comb. n. The purported evidence for the classification of certain Encarsia spp. associated with eggs of Lepidoptera as ‘heterotrophic parasitoids’ is re-examined and dismissed.
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Anaphes nitens is a solitary parasitoid of the egg capsules of the Eucalyptus snout beetle, Gonipterus scutellatus. Some traits of its natural history suggest that Local Mate Competition (LMC) could account for sex ratio adjustment in this species. We tested whether males emerged early, a prerequisite for fully local mating, and investigated the occurrence and effect of superparasitism on adult size and pre-emergence mortality, factors that might influence sex ratio adjustment. We found in field-collected egg capsules that males emerged first. To investigate the effects of superparasitism on adult size, we compared the sizes of parasitoids that emerged early and late from egg capsules collected in the field, and from egg capsules parasitized and superparasitized in the laboratory. Superparasitism reduced parasitoid size, affecting females more strongly than males, and increased pre-emergence mortality. We estimated A. nitens sex ratio and parasitism rate in the field during 2 years in five localities and during 4 years in a sixth. Following LMC we expected an increase in sex ratio (proportion of males) with increasing parasitism rate (assumed to reflect parasitoid density). We found that sex ratio decreased from 0.38 when the parasitism rate was low (0-20%) to 0.21 when parasitism was high (80-100%). In contrast with field results, a laboratory experiment showed that: (1) at a low parasitism level sex ratio was clearly female biased (0.28+/-0.04), (2) at a high parasitism level sex ratio increased (0.40+/-0.07), (3) male larval survivorship was not lower than female survivorship, and (4) low-quality hosts (i.e. superparasitized) were allocated more males. We conclude that LMC cannot explain the sex ratio adjustment observed in the field, even at low parasitism rates, and alternative explications for highly female-biased sex ratios must be found. One such alternative is female-biased dispersal.
Chapter
The mediterranean-type climate of Australia, with wet winter periods alternating with dry summer periods, is confined to the south-west corner of Western Australia, the southern portion of South Australia, and the western half of Victoria. To the north it grades into the semi-arid zone of the interior of Australia; in the east, it merges with areas receiving increasing amounts of summer rainfall. Within this zone, annual precipitation varies from 250 to 1,500 mm with 5–15% of this precipitation falling during the summer months, December to February. This small incidence of summer rainfall appears to have enabled certain growth patterns atypical of most mediterranean regions of the world to persist in the southern Australian vegetation.
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The growing of eucalypts in plantations is very new in South Australia. Few insect problems have been encountered so far though Mnesampela privata and Eriococcus coriaceous have caused considerable damage. Of more recent concern are Tryphocaria acanthocera and Heteronyx elongatus. The more common pests in eucalypt plantations are listed.
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This paper briefly summarises the status of eucalypt plantations in Victoria and identifies the insect pests that can cause severe damage to foliage during the first three years after planting on farmland, before canopy closure and foliage maturation. Also discussed are various factors presumed to predispose such plantations to severe insect attack, the nature of the damage, the present and future pest management options and the associated research.
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The increased rate of hardwood plantation establishment in Tasmania, mainly of a single species of Eucalyptus, has placed increased emphasis on the need for applied research on insect species causing damage to this resource.
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Abstract Chile has more than 330 000 ha of eucalypt plantations, predominantly in the eighth to the tenth region (approximately 34 to 41°S). Eucalyptus globulus ssp. globulus is the principal eucalypt planted, but Eucalyptus nitens, Eucalyptus camaldulensis, Eucalyptus delegatensis and Eucalyptus viminalis are also grown. There are four main insect pests that have been detected attacking these eucalypts in Chile: the defoliator Gonipterus scutellatus, the bark borers Phoracantha semipunctata and Phoracantha recurva and the native wood borer Chilecomadia valdiviana. More recently, Thyrinteina arnobia and Ctenarytaina eucalypti have been detected. Gonipterus scutellatus and P. recurva have been discovered in Chile within the last 2 years and it is hoped they may still be eliminated using a combination of biological control and chemical control of local populations. Phoracantha recurva and P. semipunctata are not considered a problem because attack only occurs in areas of water deficit, away from current eucalypt plantations. Chilecomadia valdiviana can damage plantations of E. nitens but rarely attacks other eucalypts.◊Chilecomadia valdiviana may cause future problems through further host shifts. Thyrinteina arnobia has only been detected during quarantine surveillance in the port of Valparaiso. Ctenarytaina eucalypti, recently detected in August 1999, had an initial limited distribution in the first region. However, since then, this insect has expanded its distribution south up to the tenth region. None of the insects recorded on eucalypts in Chile to date currently presents a threat to the eucalypt industry. It is also essential that additional resources are made available for their continued monitoring and control, particularly given that the 44% of plantations are held by small to medium property owners that would otherwise be unable to control a serious outbreak because of economic restrictions.
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Abstract Trends in, and potential causes of, insect pest problems of the Tasmanian blue gum, Eucalyptus globulus globulus, in south-western Australia are reviewed. Historical evidence suggests that insect pest problems of E. g. globulus in south-western Australia have greatly increased in the last 10 years, which corresponds to a time of rapid expansion of the blue gum industry in the region. Current major establishment pests include the African black beetle, Heteronychus arator, spring beetles, Liparetrus spp. and Heteronyx spp., and the wingless grasshopper, Phaulacridium vittatum. Current major pests of established trees are the Eucalyptus weevil, Gonipterus scutellatus, and chrysomelid beetles, Chrysophtharta spp. and Cadmus excrementarius. The occurrence of these insects on an introduced eucalypt is not unexpected because insect-rich native eucalypt forests dominate the landscape where E. g. globulus plantations are grown. Insect damage may also be exacerbated because E. g. globulus is grown as a monoculture.
Article
Alpha-cypermethrin is widely used in Australian forestry to control defoliating beetle pests but no information exists on its efficacy against beetle pests or impacts on non-target arthropods. To address this deficiency I quantified the short-term impacts of single commercial applications of the insecticide alpha-cypermethrin on populations of both defoliating beetle pests and beneficial arthropods over 12 months in two southwestern Australian eucalypt plantations. A single application of alpha-cypermethrin (24g a.i./ha) in October or November reduced beetle pest populations to near zero levels. Beetle recovery began immediately after spraying but high populations of eucalyptus weevil and chrysomelid beetles, and high defoliation levels did not eventuate until 10–12 months later. Despite the success of alpha-cypermethrin in controlling defoliating beetle pests, the broad-spectrum nature of the insecticide led to nearly complete mortality of all beneficial arthropods immediately after spraying. Spiders were the main group of beneficial arthropods present after spraying probably because some individuals occupy a concealed and protected habitat. Populations of Anaphes nitens (Girault), the important eucalyptus weevil egg parasitoid, also partly survived the spray because they were protected within weevil egg masses. Post-spray recovery of both beetle pests and beneficial arthropods occurred gradually in the following 12 months, presumably through immigration from outside the plantation.
Article
Gonipterus scutellatus is a significant insect pest of eucalypts in most countries where that genus has been introduced, but is usually only of minor significance in its native Australia. Because of this, much of the research on its biology and host preferences has been done outside Australia. This fact has the potential to produce misleading results as the insect may be forced to choose less preferred hosts, if normally preferred species are unavailable. In part of its native range, in Tasmania, oviposition of G. scutellatus was recorded on seven naturally co-occurring Eucalyptus species that were planted in even aged, replicated plots. Among the seven species were the economically important species, E. globulus and E. viminalis, which have been previously reported as highly preferred hosts. Within plots, oviposition occurred most commonly on three peppermint species (E. pulchella, E. tenuiramis and E. amygdalina) and was rare or absent on the other species (E. globulus, E. viminalis, E. ovata and E. obliqua). Of the peppermints, E. pulchella was the most preferred species for oviposition at this site. A low percentage of peppermints in mixed forest (containing these seven species) immediately adjacent to plots was always matched by low numbers of G. scutellatus eggs within plots; but high percentages of peppermints outside plots could either be matched by high or low numbers of eggs within plots. In the discussion, we suggest that previous studies of G. scutellatus host range may have been limited because the insect was not exposed to hosts it naturally encounters.
Article
Abstract We examined the potential of forest plantations to support communities of forest-using insects when planted into an area with greatly reduced native forest cover. We surveyed the insect fauna of Eucalyptus globulus (Myrtaceae) plantations and native Eucalyptus marginata dominated remnant woodland in south-western Australia, comparing edge to interior habitats, and plantations surrounded by a pastoral matrix to plantations adjacent to native remnants. We also surveyed insects in open pasture. Analyses focused on three major insect orders: Coleoptera, Lepidoptera and Hymenoptera. Plantations were found to support many forest-using insect species, but the fauna had an overall composition that was distinct from the remnant forest. The pasture fauna had more in common with plantations than forest remnants. Insect communities of plantations were different from native forest both because fewer insect species were present, and because they had a few more abundant insect species. Some of the dominant species in plantations were known forestry pests. One pest species (Gonipterus scutellatus) was also very abundant in remnant forest, although it was only recently first recorded in Western Australia. It may be that plantation forestry provided an ecological bridge that facilitated invasion of the native forest by this nonendemic pest species. Plantation communities had more leaf-feeding moths and beetles than remnant forests. Plantations also had fewer ants, bees, evanioid wasps and predatory canopy beetles than remnants, but predatory beetles were more common in the understory of plantations than remnants. Use of broad spectrum insecticides in plantations might limit the ability of these natural enemies to regulate herbivore populations. There were only weak indications of differences in composition of the fauna at habitat edges and no consistent differences between the fauna of plantations adjacent to remnant vegetation and those surrounded by agriculture, suggesting that there is little scope for managing biodiversity outcomes by choosing different edge to interior ratios or by locating plantations near or far from remnants.
Article
Insect-plant interactions appear to be less influenced than might be expected by the high concentrations of secondary compounds contained in eucalypt foliage; rather, levels of leaf nitrogen become significant. The tough, leathery leaves may influence the population dynamics of some eucalypt defoliators, and sclerophylly may also be significant in determining the host range of such insects. Leaf waxes and a glaucous bloom may also interfere with the activities of some herbivores. The characteristics of herbivorous insects in eucalypt forests and woodlands are indicated, and observations are made on the ecological impact of insect herbivory, including comments on rural dieback. Herbivory is also examined in the case of Eucalyptus planted as an exotic with regard both to indigenous insects adapting to eucalypts and to Australian eucalypt-feeders accidentally introduced to other countries. -P.J.Jarvis
Article
The egg parasitoid Anaphes nitens (Girault) was successfully introduced into South Africa in 1926 to control the Eucalyptus snout beetle, Gonipterus scutellatus Gyllenhal. However, outbreaks of the beetle on the Highveld in the 1980s questioned the efficacy of the parasitoid as a biological control agent and a programme was instituted to determine its present status. This study represents the Western Cape programme where 20 host egg-capsules were collected at fortnightly intervals for five years from three localities and the percentage parasitism was recorded. The mean parasitism rate varied between Cape Town (76%), George (82%), and Grabouw (89%). The highest parasitism occurred in spring (October) at Cape Town (96%) and (September) Grabouw (92%); and in autumn (May) at George (78%), coinciding with that of maximum host egg production, which in turn was dependent on the availability of fresh foliage. More host eggs were present in Cape Town (42%) than at either George (30%) or Grabouw (28%). Parasitism occurred consistently throughout the year at George which experiences all year rainfall, but the winter rainfall Cape Town and Grabouw localities experienced distinct peaks in parasitism in spring. Biological control of G. scutellatus remains effective in the Western Cape, from where A. nitens could be procured for release in Highveld regions in spring.
Article
1 In south-western Australia, Eucalyptus globulus plantations are defoliated by a complex of beetle species, yet only scant information exists on these species under such climatic conditions. To improve management of these defoliating beetles in the region, canopy fogging and shoot clipping were conducted in plantations between 1999 and 2002 to identify and document the phenology of the beetle species present.2 Eucalyptus weevil, Gonipterus scutellatus, was the most common and destructive defoliating beetle. Gonipterus scutellatus undergoes one principal generation each year with a lesser second generation or cohort in some seasons, which contrasts greatly with reports of two to four annual generations for the species in other regions. This limited reproduction by G. scutellatus may be due to the limited availability from summer onwards of new flushing foliage, which is essential for feeding and oviposition.3 Several species of chrysomelid beetles were collected in plantations, but these were present in much lower numbers than G. scutellatus and were only a minor concern. However, some species, such as Chrysophtharta variicollis, appear to be capable of developing short-lived outbreaks.4 A diverse suite of natural enemies was fogged from plantations but they were significantly less abundant than defoliating beetles and are not likely to provide significant control of beetles.5 In terms of managing these defoliating beetles, monitoring and control should focus on G. scutellatus, and be conducted during spring when most damage occurs.
Article
Anaphes nitens (Girault), the most important biological control agent of the eucalyptus snout beetle Gonipterus scutellatus, is redescribed, from specimens from South Africa. Two new species of Anaphes Haliday from Tasmania, A. tasmaniae and A. inexpectatus, also from egg pods of G. scutellatus, are described and compared with A. nitens. A key is given to separate these species. Lectotypes are designated for Anaphoidea nitens Girault and its junior synonym A. gonipteri Ferriere.
Article
1 Gonipterus scutellatus is a weevil that has become a pest in most Eucalyptus plantations in Africa, America and Europe. The egg parasitoid Anaphes nitens has been introduced into many countries as a biological control agent. Even if control has been successful in most countries no detailed study of the interactions between both species has been published. 2 Gonipterus scutellatus was detected in 1991 in north-west Spain and A. nitens was introduced in early 1994. Here we report on the results of a 2-year study of parasitism in a field plot and a survey of 16 localities in North-west Spain. In 1996, parasitism was so intense (80–100% of eggs) that G. scutellatus became locally extinct, and as a consequence A. nitens disappeared. In 1997, G. scutellatus recolonized the area and was followed by its parasitoid, but parasitism was low in spring, probably because the parasitoid population needed 3 weeks to achieve a similar size as in 1996. Consequently, damage to the trees was extreme in 1997. We interpret these results as population fluctuations due to parasitoid–host interactions and suggest that parasitoids should not to be so effective as to locally extinguish their host to be useful for biological control. 3 The analysis of parasitism level in 16 localities indicates that A. nitens is highly efficient in finding G. scutellatus egg-masses. At a small spatial scale (single trees) positive density dependence was detected where parasitism was low and inverse density dependence where parasitism was high.
Article
We studied egg production and the occurrence of adaptive superparasitism in Anaphes nitens, an egg parasitoid of the Eucalyptus snout beetle Gonipterus scutellatus. First, we determined whether A. nitens females were synovigenic or pro-ovigenic. Newly emerged females were allowed to lay eggs alone during 3 days on six fresh egg capsules. A first group of females (n = 25) were killed by freezing and the remaining females (n = 21) were maintained during two extra days with food, but without hosts. Their fecundity was measured by dissection of host eggs and females’ ovarioles. We found that the second group of females increased their fecundity by about 20%, suggesting they were weakly synovigenic. To test for the occurrence of adaptive superparasitism in relation to competitors’ density, we compared the oviposition behaviour of females kept alone, in pairs, or in groups of four during patch visit. Results indicated that the females superparasited significantly more often in this last treatment. Synovigeny and the ability to modulate the use of superparasitism could be mentioned as important attributes that allow A. nitens to efficiently control the pest population.
Article
Monthly samples of arthropods collected from foliage of newly planted bluegums (Eucalyptus globulus) during a period of 14 months revealed a diverse and abundant (35 000 individuals) fauna. Most species, however, were uncommon. Total arthropod biomass (relative to plant size) declined progressively, with minor peaks in late autumn and in the second spring. Sapsuckers dominated total biomass, with their biomass peaking in late autumn, nearly one year after planting. Chewers were the next dominant trophic level, but this was greatly biased by sporadic occurrence of large caterpillars. Predators and parasitoids each contributed <5% of total biomass.A space-for-time study of bluegums aged 6, 18 and 30 months yielded 34 000 arthropods. Total biomass increased rapidly up to 16 months and then stabilized. The proportion of sapsucker biomass halved between 18 and 30 months, while the proportion of chewer biomass increased fourfold. The greater proportion of older leaves on larger plants may have provided more suitable habitat for predators, but was less suited to sapsuckers.Observations of 11 types of chewers were collated using a conceptual framework summarizing mechanisms potentially affecting distributions of these insects in bluegum plantations in Western Australia. All four chewer types originating from agricultural habitat and reported as damaging plantations have soil-dwelling stages. Four of the five damaging chewer types originating from remnant native vegetation have feeding or oviposition preferences which are influenced by canopy development.
Gonipterus scutelatus Gyllenhal, gum tree weevil (Coleoptera: Curculionidae)
  • Nuttall
Nuttall, M.J., 1989. Gonipterus scutelatus Gyllenhal, gum tree weevil (Coleoptera: Curculionidae). In: Cameron, P.J., Hill, R.L., Bain, J., Thomas, W.P. (Eds.), A Review of Biological Control of Invertebrate Pests and Weeds in New Zealand 1874– 1987.
Do Eucalyptus plantations host an insect community similar to remnant Eucalyptus forest?
  • Cunningham