Forewarned is forearmed: harmonized approaches for early detection of potentially invasive pests and pathogens in sentinel plantings

IDphy: An International Online Resource for Molecular and Morphological Identification of Phytophthora

Phytophthora, with 203 species, is a genus of high importance in agriculture worldwide. Here, we present the online resource "IDphy", developed to facilitate the correct identification of species of Phytophthora using the type specimens from the original descriptions wherever possible. IDphy emphasizes species of high economic impact and regulatory concern for the United States. IDphy presents an interactive Lucid key and a tabular key for 161 culturable species described as of May 2018, including 141 ex-types and 20 well-authenticated specimens. IDphy contains standard operating procedures for morphological and molecular characterization, as well as a glossary, image gallery, and numerous links. Each of the 161 factsheets includes access to nomenclature and morphological and molecular features, including sequences of the internal transcribed spacer ribosomal DNA, cytochrome C oxidase subunit I (barcoding genes), YPT1, β-tubulin, elongation factor 1a, L10, heat shock protein 90, and other genes. IDphy contains an innovative in silico BLAST and phylogenetic sequence analysis using NCBI. The IDphy mobile app, released in August 2021 (free for Android or iOS), allows users to take the Lucid key into the laboratory. IDphy is the first online identification tool based on the ex-types implemented for plant pathogens. In this article, we also include information for 21 new species and one hybrid described after the publication of IDphy, the status of the specimens of the types and ex-types at international herbaria and culture collections, and the status of genomes at the GenBank (currently 153 genome assemblies which correspond to 42 described species, including 16 ex-types). The effectiveness of the IDphy online resource and the content of this article could inspire other researchers to develop additional identification tools for other important groups of plant pathogens.

Towards a global sentinel plants research strategy to prevent new introductions of non-native pests and pathogens in forests. The experience of HOMED

The use of sentinel woody plants in experimental plantings, Botanical Gardens and Arboreta has been experimentally validated as a tool for identifying possible unknown future threats prior to their introduction into new countries. Sentinel Plantings were recently established in Italy, France, Switzerland, China and South Africa, using a common experimental design. The plantings included various tree and shrub species of broadleaves and conifers. Two planting types were established, each with different objectives. In-patria plantings using native plants aim to estimate, in absence of any phytosanitary treatments, the associations and infestation rates of native insects susceptible to be exported to other countries with that particular commodity. Ex-patria plantings using non-native plants are relevant to identify native insect species capable of switching to the non-native plant that would otherwise be impossible to predict prior to its introduction. In the frame of the EU project HOMED, we have implemented this concept, widening the use of this tool simultaneously to many different countries and continents

Citizen science can enhance strategies to detect and manage invasive forest pests and pathogens

Incorporating a citizen science approach into biological invasion management strategies can enhance biosecurity. Many citizen science projects exist to strengthen the management of forest pest and pathogen invasions within both pre- and post-border scenarios. Besides the value of citizen science initiatives for early detection and monitoring, they also contribute widely to raising awareness, informing decisions about eradication and containment efforts to minimize pest and pathogen spread, and even finding resistant plant material for restoration of landscapes degraded by disease. Overall, many projects actively engage citizens in the different stages of forest pest and pathogen invasions, but it is unclear how they work together across all stages of the entire biological invasion process to enhance biosecurity. Here we provide examples of citizen science projects for each stage of the biological invasion process, discuss options for developing a citizen science program to enhance biosecurity, and suggest approaches for integrating citizen science into biosecurity measures to help safeguard forest resources in the future.

Citizen Science and Monitoring Forest Pests: a Beneficial Alliance?

Purpose of the Review

One of the major threats to tree health, and hence the resilience of forests and their provision of ecosystem services, is new and emerging pests. Therefore, forest health monitoring is of major importance to detect invasive, emerging and native pest outbreaks. This is usually done by foresters and forest health experts, but can also be complemented by citizen scientists. Here, we review the use of citizen science for detection and monitoring, as well as for hypothesis-driven research and evaluation of control measures as part of forest pest surveillance and research. We then examine its limitations and opportunities and make recommendations on the use of citizen science for forest pest monitoring.

Recent Findings

The main opportunities of citizen scientists for forest health are early warning, early detection of new pests, monitoring of impact of outbreaks and scientific research. Each domain has its own limitations, opportunities and recommendations to follow, as well as their own public engagement strategies. The development of new technologies provides many opportunities to involve citizen scientists in forest pest monitoring. To enhance the benefits of citizen scientists' inclusion in monitoring, it is important that they are involved in the cocreation of activities.

Summary

Future monitoring and research may benefit from tailor-made citizen science projects to facilitate successful monitoring by citizen scientists and expand their practice to countries where the forest health sector is less developed. In this sense, citizen scientists can help understand and detect outbreaks of new pests and avoid problems in the future.

Invasive Insect Pests of Forests and Urban Trees in Russia: Origin, Pathways, Damage, and Management

Invasive alien insects cause serious ecological and economical losses around the world. Here, we review the bionomics, modern ranges (and their dynamics), distribution pathways, monitoring, and control measures of 14 insect species known to be important invasive and emerging tree pests in forest and urban ecosystems of Russia: Leptoglossus occidentalis (Hemiptera: Heteroptera: Coreidae), Halyomorpha halys (Hemiptera: Heteroptera: Pentatomidae), Corythucha arcuata (Hemiptera: Heteroptera: Tingidae), Agrilus fleischeri, A. mali, A. planipennis, Lamprodila (Palmar) festiva (Coleoptera: Buprestidae), Ips amitinus, Polygraphus proximus (Coleoptera: Curculionidae: Scolytinae), Cydalima perspectalis (Lepidoptera: Crambidae), Acrocercops brongniardella, Cameraria ohridella, Phyllonorycter issikii, and P. populifoliella (Lepidoptera: Gracillariidae). We identified three major scenarios of tree pest invasions in the country and beyond: (1) a naturally conditioned range expansion, which results in the arrival of a pest to a new territory and its further naturalization in a recipient region; (2) a human-mediated, long-distance transfer of a pest to a new territory and its further naturalization; and (3) a widening of the pest’s trophic niche and shift to new host plant(s) (commonly human-introduced) within the native pest’s range frequently followed by invasion to new regions.

Preinvasion Assessment of Exotic Bark Beetle-Vectored Fungi to Detect Tree-Killing Pathogens

Exotic diseases and pests of trees have caused continental-scale disturbances in forest ecosystems and industries, and their invasions are considered largely unpredictable. We tested the concept of preinvasion assessment of not yet invasive organisms, which enables empirical risk assessment of potential invasion and impact. Our example assesses fungi associated with Old World bark and ambrosia beetles and their potential to impact North American trees. We selected 55 Asian and European scolytine beetle species using host use, economic, and regulatory criteria. We isolated 111 of their most consistent fungal associates and tested their effect on four important southeastern American pine and oak species. Our test dataset found no highly virulent pathogens that should be classified as an imminent threat. Twenty-two fungal species were minor pathogens, which may require context-dependent response for their vectors at North American borders, while most of the tested fungi displayed no significant impact. Our results are significant in three ways; they ease the concerns over multiple overseas fungus vectors suspected of heightened potential risk, they provide a basis for the focus on the prevention of introduction and establishment of species that may be of consequence, and they demonstrate that preinvasion assessment, if scaled up, can support practical risk assessment of exotic pathogens.

Drivers of richness and community composition of fungal endophytes of tree seeds

Recent studies revealed a high diversity of fungal endophytes in traded tree seeds, including potential plant pathogens. The factors determining richness and composition of seed mycobiomes are poorly understood, but might be an important determinant for tree health. We assessed the relative impact of host identity, site, several site-specific environmental factors, and whether the host was sampled in its native or non-native distribution range, on the richness and composition of fungal seed endophytes of nine tree species across 15 sites in Europe and North America. Our results show that fungal richness was affected by host identity, but not by environmental variables or host distribution range. Fungal community composition was primarily driven by host identity, and to a lesser extent by environment. Around 25% of the 2147 amplicon sequence variants (ASVs) were generalists appearing on both continents and in both gymnosperms and angiosperms. Around 63% of the ASVs appeared in only gymnosperms or angiosperms, and 33% of the ASVs were associated with a single host species, while none were found in all tree species. Our results suggest that although seed trade might facilitate movements of fungi, their establishment and spread in the new environment might be limited by host availability.

Estimating Potential Distribution of Sweetgum Pest Acanthotomicus suncei and Potential Economic Losses in Nursery Stock and Urban Areas in China

Simple Summary

American sweetgum Liquidambar styraciflua (Altingiaceae) was introduced to China over 60 years ago. It is an important tree species for increasing landscape value and promoting afforestation in urbanized areas of eastern China in the past 20 years. Sweetgum inscriber Acanthotomicus suncei is a local bark beetle pest and lethal to the introduced American sweetgum. To estimate the potential economic losses caused by the sweetgum inscriber, we survey the beetles’ natural distribution in China. Based on field collections, potential distribution was predicted. Nurseries stocking American sweetgum were found in the high suitability area of this pest. Additionally, we predict the direct loss incorporating tree and removal cost. A questionnaire was sent to maintenance companies, growers, and gardener associations for tree removal prices. In addition, the market price and inventory were also gained from telephone interview. Our economic analysis indicates that if sweetgum inscriber were to become established in the main American sweetgum business, the potential losses of nursery stock and urban area could range from USD 12.81 to 14.41 million. The results will serve as a baseline measure to control urban forest pests.

Abstract

American sweetgum Liquidambar styraciflua (Altingiaceae) was first introduced to China over 60 years ago. It is an important tree species for increasing landscape value and promoting afforestation in urbanized areas of eastern China in the past 20 years. Sweetgum inscriber Acanthotomicus suncei (Coleoptera: Curculionidae) is a local bark beetle pest and lethal to the introduced American sweetgum. To provide preliminary estimates of the potential economic losses caused by the sweetgum inscriber, a field investigation was conducted to survey the beetles’ natural distribution in China. Based on field collections, potential distribution was predicted using Maxent. All nurseries stocking American sweetgum were in the high and very high suitability area of sweetgum inscriber. Additionally, we employed a model of direct loss incorporating tree and removal cost. A questionnaire was sent to maintenance companies, growers, and gardener associations for tree removal prices. We estimated the removal cost of each tree. In addition, the market price and inventory were also gained from telephone interview. Our economic analysis indicates that if sweetgum inscriber were to become established in the main American sweetgum business, the potential losses of nursery stock and urban area could range from USD 12.81 to 14.41 million.