Publications by authors named "Jactel H"

The European Commission requested the EFSA Panel on Plant Health to deliver a risk assessment on the likelihood of pest freedom from regulated EU quarantine pests, with emphasis on and its vectors spp. of debarked conifer wood chips fumigated with sulfuryl fluoride as proposed by the United States (US) and as outlined in ISPM 28 - PT23 of sulfuryl fluoride (SF) fumigation treatment for nematodes and insects in debarked wood. The assessment considered the different phases in the wood chips' production, with special emphasis on the SF treatment.

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The European Commission requested the EFSA Panel on Plant Health to prepare and deliver risk assessments for commodities listed in Commission Implementing Regulation (EU) 2018/2019 as 'high-risk plants, plant products and other objects'. Taking into account the available scientific information, including the technical information provided by the applicant country, this Scientific Opinion covers the plant health risks posed by the following commodities: , and graftwood, bare-root plants and rooted plants in pots up to 7 years old imported into the EU from the UK. A list of pests potentially associated with the commodities was compiled.

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Pest categorisation of .

EFSA J

January 2025

Following the commodity risk assessment of plants grafted on from China, in which (Hemiptera: Diaspididae) was identified as a pest of possible concern, the European Commission requested the EFSA Panel on Plant Health to conduct a pest categorisation of for the territory of the European Union (EU). The origin of the scale insect is uncertain, with either South America or eastern Asia suggested as the native range. The geographic distribution of the species includes many countries of the continents of Africa, North and South America, Asia and Oceania.

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Pest categorisation of .

EFSA J

January 2025

Following the commodity risk assessment of and plants for planting from Türkiye, in which (Hemiptera: Diaspididae), the pistachio oyster scale or yellow pistachio scale, was identified as a pest of possible concern, the EFSA Panel on Plant Health performed a pest categorisation for the territory of the European Union (EU). is reported as a polyphagous pest which, however, mainly affects plants of the genus Originating from Asia, it is widely distributed in pistachio producing countries of Central, South and West Asia. Within the EU, the pest has been reported from Cyprus and Greece.

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The European Commission requested the EFSA Panel on Plant Health to prepare and deliver risk assessments for commodities listed in Commission Implementing Regulation (EU) 2018/2019 as 'High-risk plants, plant products and other objects'. This Scientific Opinion covers plant health risks posed by plants of hybrids of x imported from Ukraine, taking into account the available scientific information, including the technical information provided by Ukraine. All pests that may be associated with the hybrids of x were evaluated against specific criteria for their relevance for this opinion.

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Article Synopsis
  • - The European Commission tasked the EFSA Panel on Plant Health with assessing the risk of pests related to unrooted cuttings produced in Costa Rica, focusing on both regulated and non-regulated pests.
  • - A total of 22 regulated pest species were identified, including various viruses affecting plants, and were analyzed for potential entry risks and the effectiveness of Costa Rica's risk mitigation strategies.
  • - The evaluation concluded that while the risk of pest contamination varied among those studied, there is a high likelihood (95% certainty) that most unrooted cuttings would be free of the tomato spotted wilt virus, estimating that 9,927 to 10,000 out of 10,000 bags would not carry this pest. *
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Article Synopsis
  • The European Commission tasked the EFSA Panel on Plant Health to assess the plant health risks of high-risk commodities imported from the UK, as listed in EU regulation 2018/2019.
  • The risk assessment categorized the commodities into four groups, including graftwood, bare root plants, potted plants, and large specimen trees, and evaluated pests linked to these groups.
  • Two EU quarantine pests were identified for further evaluation based on their relevance, with the assessment considering factors like plant age and the effectiveness of risk mitigation measures from the UK.
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Increasing tree diversity is considered a key management option to adapt forests to climate change. However, the effect of species diversity on a forest's ability to cope with extreme drought remains elusive. In this study, we assessed drought tolerance (xylem vulnerability to cavitation) and water stress (water potential), and combined them into a metric of drought-mortality risk (hydraulic safety margin) during extreme 2021 or 2022 summer droughts in five European tree diversity experiments encompassing different biomes.

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Article Synopsis
  • Recent droughts are worsening and expected to affect forest ecosystems more frequently and intensely due to climate change.
  • Research shows that having more tree species in a plantation can reduce the stress on trees during drought events, reflected by changes in leaf carbon and nitrogen isotopes.
  • Higher tree species richness leads to lower drought stress (lower leaf δC) and changes in nitrogen cycling during drought (higher leaf δN), indicating that diverse tree plantations might perform better under severe drought conditions.
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Neonicotinoids are the top-selling insecticides worldwide. Because of their method of use, mainly to coat seeds, neonicotinoids have been found to widely contaminate the environment. Their high toxicity has been shown to be a major concern in terms of impact on biodiversity, and the use of these insecticides has been associated with population declines of species in different countries.

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Tree diversity can promote both predator abundance and diversity. However, whether this translates into increased predation and top-down control of herbivores across predator taxonomic groups and contrasting environmental conditions remains unresolved. We used a global network of tree diversity experiments (TreeDivNet) spread across three continents and three biomes to test the effects of tree species richness on predation across varying climatic conditions of temperature and precipitation.

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Plant diversity effects on community productivity often increase over time. Whether the strengthening of diversity effects is caused by temporal shifts in species-level overyielding (i.e.

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Pesticides used for plant protection can indirectly affect target and non-target organisms and are identified as a major cause of insect decline. Depending on species interactions, pesticides can be transferred into the environment from plants to preys and predators. While the transfer of pesticides is often studied through vertebrate and aquatic exposure, arthropod predators of insects may represent valuable bioindicators of environmental exposure to pesticides.

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The Japanese beetle, , is native to Japan and became established in North America in the early twentieth century. The beetle was detected in Europe, first in Italy in 2014 and then in Switzerland in 2017. Metropolitan France is at the forefront of the Japanese beetle threat, due to its geographical proximity to the European populations established in the Piedmont, Lombardy and Ticino regions.

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Article Synopsis
  • The 'Global Spectrum of Plant Form and Function Dataset' includes mean values for six key vascular plant traits, essential for understanding plant variation.
  • This dataset aggregates around 1 million trait records from the TRY database and other sources, encompassing 92,159 species mean values across 46,047 species.
  • Comprehensive data quality management and validation ensure this is the largest and most reliable collection of empirical data on vascular plant traits available.
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  • Litter decomposition is an important ecological process in forests, influenced by climate, soil, and local characteristics, making it difficult to assess the specific impacts of these factors.
  • A study using data from 15 tree diversity experiments across multiple countries found that tree species identity and plantation conditions significantly impact the rate of litter decomposition, particularly for low-quality litter.
  • After one year, while temperature mainly affected high-quality litter decomposition, the decomposition of low-quality litter was more related to overstory composition and the age of the tree plantations.
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Current climate change aggravates human health hazards posed by heat stress. Forests can locally mitigate this by acting as strong thermal buffers, yet potential mediation by forest ecological characteristics remains underexplored. We report over 14 months of hourly microclimate data from 131 forest plots across four European countries and compare these to open-field controls using physiologically equivalent temperature (PET) to reflect human thermal perception.

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  • Research discusses how current global climate models are based on air temperatures but fail to capture the soil temperatures beneath vegetation where many species thrive.
  • New global maps present soil temperature and bioclimatic variables at 1-km resolution for specific depths, revealing that mean annual soil temperatures can differ significantly from air temperatures by up to 10°C.
  • The findings indicate that relying on air temperature could misrepresent climate impacts on ecosystems, especially in colder regions, highlighting the need for more precise soil temperature data for ecological studies.
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Tree species diversity promotes multiple ecosystem functions and services. However, little is known about how above- and belowground resource availability (light, nutrients, and water) and resource uptake capacity mediate tree species diversity effects on aboveground wood productivity and temporal stability of productivity in European forests and whether the effects differ between humid and arid regions. We used the data from six major European forest types along a latitudinal gradient to address those two questions.

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Plant functional traits can predict community assembly and ecosystem functioning and are thus widely used in global models of vegetation dynamics and land-climate feedbacks. Still, we lack a global understanding of how land and climate affect plant traits. A previous global analysis of six traits observed two main axes of variation: (1) size variation at the organ and plant level and (2) leaf economics balancing leaf persistence against plant growth potential.

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One promising approach to mitigate the negative impacts of insect pests in forests is to adapt forestry practices to create ecosystems that are more resistant and resilient to biotic disturbances. At the stand scale, local stand management practices often cause idiosyncratic effects on forest pests depending on the environmental context and the focal pest species. However, increasing tree diversity appears to be a general strategy for reducing pest damage across several forest types.

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The functioning of present ecosystems reflects deep evolutionary history of locally cooccurring species if their functional traits show high phylogenetic signal (PS). However, we do not understand what drives local PS. We hypothesize that local PS is high in undisturbed and stressful habitats, either due to ongoing local assembly of species that maintained ancestral traits, or to past evolutionary maintenance of ancestral traits within habitat species-pools, or to both.

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For non-native tree species with an origin outside of Europe a detailed compilation of enemy species including the severity of their attack is lacking up to now. We collected information on native and non-native species attacking non-native trees, i.e.

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Forest pests can cause massive ecological and economic damage worldwide. Ecologically sound solutions to diminish forest insect pest impacts include the use of their natural enemies, such as predators and parasitoids, as well as entomopathogenic fungi, bacteria or viruses. Phytochemical compounds mediate most interactions between these organisms, but knowledge of such chemically mediated multitrophic relationships is still at its infancy for forest systems, particularly when compared to agricultural systems.

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