Explore the vast range of titles available.

The eucalyptus snout beetle (ESB), Gonipterus platensis , is endemic to Australia but has become a major invasive, destructive pest of Brazilian eucalyptus plantations. Efforts to develop insecticides based on entomopathogenic fungi against ESB are limited by the lack of known virulent strains. We therefore explored the virulence of indigenous Brazilian strains of major entomopathogenic fungi— Beauveria spp. and Metarhizium anisopliae —against ESB adults. We found widely varying virulence and later capacities for conidial production on infected adult cadavers. Two strains stood out, B. bassiana IBCB-240 and M. anisopliae IBCB-364, as especially lethal for ESB adults under laboratory conditions, sporulated abundantly on infected insects, and also outperformed comparable strains used in commercial mycoinsecticides. Notably, B. bassiana IBCB-240 exhibited lower LT 50 values at low inoculum levels (≤ 10 7 conidia mL −1 ) and smaller LC 50 values than M. anisopliae IBCB-364. Taken together, this study emphasizes natural variation in virulence among indigenous Beauveria and Metarhizium strains against ESB adults and identifies fungal strains with superior lethality to existing commercialized strains for managing this eucalyptus pest in Brazil.

Ribeiro et al discuss the first detection of Gonipterus platensis and its parasitoid Anaphes nitens in eucalyptus plantations in Minas Gerais, Brazil. The area with forest plantations in Brazil is one of the largest in the world, 9.93 million hectares with 75.8% (7.53 million ha) of eucalyptus plantations with a mean annual productivity of 38.9 m3/ha. These plantations are used to produce raw materials, mainly for the bioenergy, pulp and paper and laminate flooring sectors. Minas Gerais is the Brazilian state with the largest area of eucalyptus plantations, more than 2 million hectares, followed by the Mato Grosso do Sul and Sao Paulo states. Insect pests, especially exotic ones, damage these plantations.

Multidimensional gas chromatography is, presently, an established and powerful analytical tool, due to higher resolving power than the classical 1D chromatographic approaches. Applied to multiple areas, it allows to isolate, detect and identify a larger number of compounds present in complex matrices, even in trace amounts. Research was conducted to determine which compounds, emitted by host plants of the eucalyptus weevil, Gonipterus platensis, might mediate host selection behavior. The identification of a pheromone blend of G. platensis is presented, revealing to be more attractive to weevils of both sexes, than the individual compounds. The volatile organic compounds (VOCs) were collected by headspace solid phase microextraction (HS-SPME), MonoTrapTM disks, and simultaneous distillation-extraction (SDE). Combining one dimensional (1D) and two-dimensional (2D) chromatographic systems—comprehensive and heart-cut two-dimensional gas chromatography (GC×GC and H/C-MD-GC, respectively) with mass spectrometry (MS) and electroantennographic (EAD) detection, enabled the selection and identification of pertinent semiochemicals which were detected by the insect antennal olfactory system. The behavioral effect of a selected blend of compounds was assessed in a two-arm olfactometer with ten parallel walking chambers, coupled to video tracking and data analysis software. An active blend, composed by cis and trans-verbenol, verbenene, myrtenol and trans-pinocarveol was achieved.

• Key messageGonipterus platensisis an important insect pest of eucalypt plantations. Despite biological control by the egg parasitoidAnaphes nitens, economic losses remain high in several areas outside its native range where susceptible eucalypt species are grown in commercial plantations. The susceptibility toG. platensisof 17Eucalyptusspecies was evaluated and possible alternatives for reforestation in high pest incidence areas were identified.• ContextGonipterus platensis is an important pest of Eucalyptus worldwide. Despite biological control, it causes significant losses to Eucalyptus plantations in several areas, requiring alternative management options.• AimsWe analysed host preference of G. platensis towards 17 Eucalyptus species to identify less susceptible plant materials that could be used in areas of high pest incidence.• MethodsFeeding damage was assessed in field trials in three consecutive years. No-choice and choice tests were conducted with Eucalyptus species of contrasting susceptibility.• ResultsWithin subgenus Symphyomyrtus, all species from section Maidenaria were used by G. platensis for feeding. Within this section, E. globulus was always the preferred species, while E. nitens was the least preferred. Differences in susceptibility were less pronounced at high attack intensity by G. platensis. Eucalyptus saligna (section Latoangulatae) was the least preferred species among Symphyomyrtus. All species from subgenus Eucalyptus had low susceptibility to G. platensis, particularly E. regnans, which was never attacked under field conditions. The results were confirmed by choice and no-choice laboratory and semi-field tests.• ConclusionSignificant differences in susceptibility to G. platensis were found between the 17 Eucalyptus species tested, which could be explored for reforestation with less susceptible plant materials.

Eucalyptus plantations worldwide experience significant productivity losses due to herbivory caused by the weevil Gonipterus platensis (Coleoptera: Curculionidae. Marelli 1927); however, the role of leaf nutritional status in host preference remains poorly understood. In this study, we evaluated the incidence and severity of defoliation on two seed-propagated eucalypts—Eucalyptus globulus Labill. and Eucalyptus nitens Maiden, as well as two clonally propagated E. nitens × E. globulus hybrids—at a trial site in Mulchén, Chile. Sampling occurred after peak weevil activity (December 2022) and during austral autumn (May 2023). We determined foliar concentrations of nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), boron (B), carbon (C), and the carbon-to-nitrogen (C/N) ratio, and analyzed their relationships with herbivory using ANOVA, principal component analysis (PCA), and linear regression. Overall defoliation was low (<7%), but significantly higher on E. globulus, with hybrids exhibiting intermediate damage. Seasonally, N and Mg concentrations declined, while K and Ca levels increased, resulting in an elevated C/N ratio in autumn. A positive correlation was observed between leaf Ca concentration and both the incidence and severity of herbivory during peak activity in the susceptible E. globulus genotype (R2 = 0.96, p < 0.05). These findings suggest that calcium accumulation may influence weevil feeding preferences. Further research should explore nutrient-mediated resistance to guide selection and fertilization strategies for developing more resilient eucalyptus varieties.

BACKGROUND: Gonipterus platensis Marelli, 1926 (Coleoptera: Curculionidae) is one of the main defoliating beetles in Eucalyptus plantations. Biological control with egg parasitoids is one of the main control strategies for this pest and a constant supply of fresh host eggs is required to rear the parasitoids. Polyandry can influence Gonipterus oviposition by increasing female fecundity and fertility; however, the high density of individuals in laboratory colonies can lead to male harassment, resulting in lower reproduction rate. The aim of this study was to measure the effects of monoandry and polyandry on the reproduction of G. platensis and the effects of male harassment on laboratory rearing conditions. METHODS: Reproductive parameters were compared between three treatments: monoandry, where the female was allowed to mate daily with the same male; no choice polyandry, where the female was allowed to mate daily with a different male; and polyandry with choice, where the female was allowed to mate daily, but with a choice between five different males. Another experiment varying the density of males was conducted to evaluate the effect of male harassment. RESULTS: Polyandry with choice resulted in the longest period of oviposition, highest fecundity and highest number of eggs per egg capsules when compared to monoandrous females. No negative effect related to male harassment in the laboratory, such as decreased fertility, fecundity, or number of eggs per egg capsule, was detected. CONCLUSION: Polyandry contributes to mass rearing as it increases fecundity and oviposition period on females and there is no evidence of male harassment on G. platensis.

Eucalyptus snout beetles are a complex of at least eight cryptic species (Curculionidae: Gonipterus scutellatus complex), native to mainland Australia and Tasmania, that defoliate Eucalyptus trees and are considered important pests. Since the 19th century, three species of the complex have been introduced to other continents. Here, we document the presence of Eucalyptus snout beetles in Ecuador. We used DNA data for species identification and unambiguously demonstrated that the Ecuadorian specimens belong to the species Gonipterus platensis, which has low genetic diversity compared with other species in the complex. We analyzed G. platensis' potential distribution in South America with ecological niche models and found several areas of high to intermediate climatic suitability, even in countries where the pest has not been registered, like Peru and Bolivia. Accurate identification of species in the G. scutellatus complex and understanding of their potential distribution are essential tools for improved management and prevention tactics. Resumen Los gorgojos del eucalipto son un complejo de al menos ocho especies crípticas (Curculionidae: complejo Gonipterus scutellatus), nativos de Australia continental y Tasmania, que defolian árboles de eucalipto y son considerados como plagas de importancia. Desde el siglo 19, tres especies de este complejo se han introducido a otros continentes. En este trabajo reportamos la presencia de gorgojos del eucalipto en Ecuador. Usamos datos genéticos para la identificación específica y demostramos claramente que los especímenes ecuatorianos pertenecen a la especie Gonipterus platensis, la cual tiene baja diversidad genética comparada con otras especies en el complejo. Analizamos la distribución potencial de G. platensis en América del Sur con modelos de nicho ecológico y encontramos varias áreas con idoneidad ambiental alta a intermedia, incluso en países donde esta especie no ha sido registrada, como Perú y Bolivia. La correcta identificación de las especies del complejo Gonipterus scutellatus y una mejor comprensión de su distribución potencial constituyen herramientas fundamentales para optimizar medidas de manejo y prevención. We report the presence of the Eucalyptus snout beetle, Gonipterus platensis, in Ecuador. Ecological niche modeling revealed areas of climatic suitability in South America where this species is present or could invade in the future.

Microsporidia are naturally occurring fungal-related parasites that can infect nearly all animal hosts, but their biocontrol potential of insect pests is routinely overlooked in agriculture and forestry. This research brings the first report describing the natural occurrence of a microsporidium causing disease in field-collected populations of the invasive eucalyptus snout beetle, Gonipterus platensis (Coleoptera: Curculionidae), a major destructive pest of eucalyptus plantations in Brazil. Adult beetles were collected during field surveys in commercial eucalyptus plantations in southern Brazil to be examined and dissected with typical symptoms to verify presence of microsporidian spores in haemolymph. From 14 plantations in different sites, the natural infection occurrence in these populations ranged from 0 to 65%, while a lab colony exhibited an infection incidence of 70%. Spore density in haemolymph of symptomatic insects averaged 2.1 (± 0.4) × 10 7 spores/beetle. Symptoms in infected adults were identified by an abnormal abdomen with malformation of the second pair of wings, impairing their flight activity. Electron transmission microscopy of the pathogen showed morphological features similar to species belonging to the genus Nosema or Vairimorpha. Phylogenetic analysis of the full-length small subunit ribosomal RNA gene suggests this pathogen’s placement in the genus Vairimorpha, but with a sequence identity of ~ 94% with the nearest neighbours. The low level of sequence identity suggests this pathogen may represent a novel taxon in the genus and further requires whole genome sequencing for definitive taxonomic resolution. These findings provide insights on the natural occurrence of this novel pathogen of this invasive pest in Eucalyptus plantations in Brazil. Further studies are needed to determine potential of this microsporidium in the design of conservative or augmentative biological control programs for this invasive pest.

Background Anaphes nitens (Girault, 1928) (Hymenoptera: Mymaridae) is an egg parasitoid used for the biological control of Gonipterus spp. in regions where this pest is present. Cold storage of host eggs is a crucial strategy in biological control programs. This study aimed to evaluate the effects of cold storage on G. platensis eggs for laboratory rearing of both the host and its parasitoid, A. nitens. Methods Gonipterus platensis eggs, aged 1 and 3 days, were stored in a refrigerator at 7 ± 1 °C for 5, 10, 20, 30, 40, and 50 days in complete darkness. After each storage period, the eggs were transferred to a biochemical oxygen demand (BOD) chamber at 25 °C and hatching rates and larval survival were assessed. To evaluate parasitoid reproduction, fresh host eggs were stored at 7 ± 1 °C for 5, 10, 15, 20, and 25 days under dark conditions and subsequently exposed to A. nitens. Parasitism rate, sex ratio, and offspring longevity were recorded. Results Results showed that 1- and 3-day-old G. platensis eggs maintained the highest viability within the first 10 days of storage, with hatching rates exceeding 50% up to 20 days post-storage. A 20-day storage period was the longest duration that did not differ significantly from the non-stored eggs (control) considering A. nitens parasitism and progeny longevity when stored host eggs were offered. Conclusion Therefore, storing host eggs for this period effectively supports colony maintenance while simultaneously facilitating parasitoid propagation.

Abstract Gonipterus platensis Marelli (Coleoptera: Curculionidae) has been detected for the first time in the Caazapá Department, Paraguay. This species is closely related to the eucalyptus snout beetle, which is an invasive pest native to Australia, that causes serious damage to eucalyptus plantations. Gonipterus platensis belongs to a complex of cryptic species (Gonipterus scutellatus species complex) that share morphological similarities, making species differentiation challenging. In addition, oothecae parasitized by Anaphes nitens Girault (Hymenoptera: Mymaridae) were found. This record highlights the importance of conducting further studies on the biology and establishment of G. platensis in Paraguay as well as exploring the potential of biological control using A. nitens as a part of an integrated pest management strategy. Graphical Abstract Una de las varias especies de gorgojos defoliadores del eucalipto, Gonipterus platensis, fue detectada por primera vez en el Departamento de Caazapá, Paraguay. Esta plaga causa serios daños en las plantaciones de eucalipto, poniendo en riesgo su valor comercial. Se detectaron además varias ootecas de G. platensis parasitadas por Anaphes nitens, un micro-himenóptero que podría ser utilizado como agente de control biológico como parte de una estrategia de manejo integrado de plagas del gorgojo del eucalipto. Alt text: Picture showing Gonipterus platensis mating in natural conditions and its egg parasitoid Anaphes nitens.