Utility of essential oils for development of host-based lures for Xyleborus glabratus (Coleoptera: Curculionidae: Scolytinae), vector of laurel wilt

AbstractRedbay ambrosia beetle, Xyleborus glabratus, is native to Southeast Asia, but subsequent to introduction in Georgia in 2002, it has become a serious invasive pest in the USA, now established in nine southeastern states. Females vector Raffaelea lauricola, the fungus that causes laurel wilt, a lethal vascular disease of trees in the family Lauraceae. Laurel wilt has caused extensive mortality in native Persea species, including redbay (P. borbonia), swampbay (P. palustris), and silkbay (P. humilis). Avocado (P. americana) is now impacted in Florida, and with continued spread, laurel wilt has potential to affect avocado and native Lauraceae in California, Mexico, and throughout the American tropics. Effective lures for detection and control of X. glabratus are critical to slow the spread of laurel wilt. No pheromones are known for this species; primary attractants are volatile terpenoids emitted from host Lauraceae. This report provides a concise summary of the chemical ecology of X. glabratus, highlighting research to identify kairomones used by females for host location. It summarizes development of essential oil lures for pest detection, including discussions of the initial use of phoebe and manuka oil lures, the current cubeb oil lure, and a newly-developed distilled oil lure enriched in (-)-α-copaene.

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Genetic Analyses of the Laurel Wilt Pathogen, Raffaelea lauricola, in Asia Provide Clues on the Source of the Clone that is Responsible for the Current USA Epidemic

Forests ◽

10.3390/f10010037 ◽

2019 ◽

Vol 10 (1) ◽

pp. 37 ◽

Cited By ~ 4

Author(s):

Tyler J. Dreaden ◽

Marc A. Hughes ◽

Randy C. Ploetz ◽

Adam Black ◽

Jason A. Smith

Keyword(s):

Genetic Structure ◽

Laurel Wilt ◽

Type Locus ◽

Xyleborus Glabratus ◽

Genetic Structure Of Populations ◽

Raffaelea Lauricola ◽

Host Trees ◽

Redbay Ambrosia Beetle ◽

The Usa ◽

Simple Sequence

Laurel wilt is caused by the fungus Raffaelea lauricola T.C. Harr., Fraedrich and Aghayeva, a nutritional symbiont of its vector the redbay ambrosia beetle, Xyleborus glabratus Eichhoff. Both are native to Asia but appeared in Georgia in the early 2000s. Laurel wilt has since spread to much of the southeastern United States killing >300 million host trees in the Lauraceae plant family. The aims of this research were to elucidate the genetic structure of populations of R. lauricola, to examine its reproductive strategy, and determine how often the pathogen had been introduced to the USA. A panel of 12 simple sequence repeat (SSR) markers identified 15 multilocus genotypes (MLGs) in a collection of 59 isolates from the USA (34 isolates), Myanmar (18), Taiwan (6) and Japan (1). Limited diversity in the USA isolates and the presence of one MAT idiotype (mating type locus) indicated that R. lauricola was probably introduced into the country a single time. MLG diversity was far greater in Asia than the USA. Only three closely related MLGs were detected in the USA, the most prevalent of which (30 of 34 isolates) was also found in Taiwan. Although more work is needed, the present results suggest that a Taiwanese origin is possible for the population of R. lauricola in the USA. Isolates of R. lauricola from Myanmar were distinct from those from Japan, Taiwan and the USA. Although both MAT idiotypes were present in Myanmar and Taiwan, only the population from Taiwan had the genetic structure of a sexually reproducing population.

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Raffaelea lauricola (laurel wilt).

10.1079/cpc.109424.20210104916 ◽

2021 ◽

Author(s):

Stephen Fraedrich

Keyword(s):

Solid Wood ◽

Persea Americana ◽

South Florida ◽

Florida Current ◽

Natural Ecosystems ◽

Laurel Wilt ◽

Southeastern Usa ◽

Raffaelea Lauricola ◽

Redbay Ambrosia Beetle ◽

The Usa

Abstract Laurel wilt is responsible for the death of hundreds of millions of redbay (Persea borbonia sensu lato) trees throughout the southeastern USA, and the disease is also having significant effects on other species such as sassafras (Sassafras albidum) in natural ecosystems and avocado (Persea americana) in commercial production areas of south Florida. Laurel wilt is caused by the pathogen Raffaelea lauricola, a fungal symbiont of the redbay ambrosia beetle, Xyleborus glabratus. Thus far, the disease is confined to members of the Lauraceae that are native to the USA, or native to such places as the Caribbean, Central America and Europe and grown in the USA. The beetle and fungus are native to Asia and were likely introduced with untreated solid wood packing material at Port Wentworth, Georgia in the early 2000s. Since that time laurel wilt has spread rapidly in the coastal plains of the southeastern USA, spreading north into central North Carolina, as far west as Texas, and reaching the southernmost counties of Florida. Current models suggest that X. glabratus can tolerate temperature conditions that occur throughout much of the eastern USA, and so the disease threatens sassafras throughout much of this region. The disease poses a threat to lauraceous species indigenous to other areas of the Americas as well as Europe and Africa.

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Isolations from the redbay ambrosia beetle, Xyleborus glabratus, confirm that the laurel wilt pathogen, Raffaelea lauricola, originated in Asia

Mycologia ◽

10.3852/10-417 ◽

2011 ◽

Vol 103 (5) ◽

pp. 1028-1036 ◽

Cited By ~ 64

Author(s):

Thomas C. Harrington ◽

Hye Young Yun ◽

Sheng-Shan Lu ◽

Hideaki Goto ◽

Dilzara N. Aghayeva ◽

...

Keyword(s):

Ambrosia Beetle ◽

Laurel Wilt ◽

Xyleborus Glabratus ◽

Raffaelea Lauricola ◽

Redbay Ambrosia Beetle

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Raffaelea lauricola (Laurel wilt).

10.1079/isc.109424.20210198934 ◽

2021 ◽

Author(s):

Stephen Fraedrich

Keyword(s):

Solid Wood ◽

Persea Americana ◽

South Florida ◽

Florida Current ◽

Natural Ecosystems ◽

Laurel Wilt ◽

Southeastern Usa ◽

Raffaelea Lauricola ◽

Redbay Ambrosia Beetle ◽

The Usa

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Use of Semiochemicals for the Management of the Redbay Ambrosia Beetle

Insects ◽

10.3390/insects11110796 ◽

2020 ◽

Vol 11 (11) ◽

pp. 796

Author(s):

Xavier Martini ◽

Marc A. Hughes ◽

Derrick Conover ◽

Jason Smith

Keyword(s):

Detrimental Effect ◽

Pathogenic Fungus ◽

Urban Trees ◽

Ambrosia Beetle ◽

Laurel Wilt ◽

Pull System ◽

Xyleborus Glabratus ◽

Raffaelea Lauricola ◽

Redbay Ambrosia Beetle ◽

Primary Vector

This review highlights current advances in the management of the redbay ambrosia beetle, Xyleborus glabratus, a primary vector of the pathogenic fungus, Raffaelea lauricola, that causes laurel wilt. Laurel wilt has a detrimental effect on forest ecosystems of southeastern USA, with hundreds of millions of Lauraceae deaths. Currently, preventive measures mostly focus on infected-tree removal to potentially reduce local beetle populations and/or use of preventative fungicide applications in urban trees. Use of semiochemicals may offer an opportunity for the management of X. glabratus. Research on attractants has led to the development of α-copaene lures that are now the accepted standards for X. glabratus sampling. Research conducted on repellents first included methyl salicylate and verbenone and attained significant reduction in the number of X. glabratus captured on redbay and swamp bay trees treated with verbenone. However, the death rate of trees protected with verbenone, while lower compared to untreated trees, is still high. This work underscores the necessity of developing new control methods, including the integration of repellents and attractants into a single push-pull system.

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First Report of Laurel Wilt Disease Caused by Raffaelea lauricola on Camphor in Florida and Georgia

Plant Disease ◽

10.1094/pdis-93-2-0198b ◽

2009 ◽

Vol 93 (2) ◽

pp. 198-198 ◽

Cited By ~ 28

Author(s):

J. A. Smith ◽

L. Mount ◽

A. E. Mayfield ◽

C. A. Bates ◽

W. A. Lamborn ◽

...

Keyword(s):

South Carolina ◽

Resistance Mechanisms ◽

Small Subunit ◽

Residential Areas ◽

Laurel Wilt ◽

Xyleborus Glabratus ◽

Raffaelea Lauricola ◽

Redbay Ambrosia Beetle ◽

Persea Borbonia ◽

Branch Dieback

Laurel wilt is a recently described (1) vascular disease of redbay (Persea borbonia (L.) Spreng) and other plants in the family Lauraceae. The wilt is caused by Raffaelea lauricola, a fungus vectored by the nonnative redbay ambrosia beetle (Xyleborus glabratus Eichhoff) (1,2). Since 2003, laurel wilt has caused widespread mortality of redbay in Georgia, South Carolina, and Florida (1) and has recently been found on avocado in Florida (4). Since June of 2007, wilted shoots and branch dieback have been observed in several camphor trees (Cinnamomum camphora (L.) Sieb.) in residential areas of McIntosh and Glynn counties in Georgia and Baker County in Florida. Symptomatic camphor trees ranged from 4.5 to 12 m high and occurred in areas where redbay mortality due to laurel wilt has been frequently observed during the last 2 to 3 years. In some camphor trees, only the smaller branches (<2 cm in diameter) were wilting or dead, whereas in other trees (e.g., Baker County, Florida), the larger branches and substantial portions of the crown were also symptomatic. Rapid wilt that affects entire trees that is usually observed in redbay, has not been observed in camphor. Some camphor trees in residential areas of Jekyll Island, Georgia (Glynn County), where extensive wilt of redbay has occurred, have exhibited only localized wilt of some shoots or branches and other camphors remain asymptomatic. Removal of bark from wilted branch sections revealed black-to-brownish staining in the sapwood, characteristic of laurel wilt. Although no evidence of ambrosia beetles was observed on these samples, more extensive surveys are needed to determine the role of this vector in laurel wilt of camphor. Wood chips from symptomatic areas of branches were surface sterilized and plated on cycloheximide-streptomycin malt agar as previously described (1,4) and R. lauricola was routinely isolated. Small subunit (18S) sequences from rDNA were amplified by PCR and sequenced using primers NS1 and NS4 (3). BLASTn searches revealed homology to R. lauricola C2203 (GenBank Accession No. EU123076, 100% similarity, e-value of 0.0, and a total score of 1,886). The small subunit rDNA sequence for this isolate has been deposited into GenBank ( http://www.ncbi.nlm.nih.gov/Genbank/index.html ) and has been assigned Accession No. EU 853303. The presence of laurel wilt in camphor provides an opportunity to understand the pathogen distribution and possible resistance mechanisms in this host, which could have implications for efforts to remediate the impacts of the disease in redbay and other species in the Lauraceae in the southeastern United States. References: (1) S. W Fraedrich et al. Plant Dis. 92:215, 2008. (2) T. C. Harrington et al. Mycotaxon 104:399, 2008. (3) M. A. Innis et al. PCR Protocols, A Guide to Methods and Applications. Academic Press. San Diego, CA, 1990. (4) A. E. Mayfield, III et al. Plant Dis. 92:976, 2008.

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Quantification of Propagules of the Laurel Wilt Fungus and Other Mycangial Fungi from the Redbay Ambrosia Beetle, Xyleborus glabratus

Phytopathology ◽

10.1094/phyto-01-10-0032 ◽

2010 ◽

Vol 100 (10) ◽

pp. 1118-1123 ◽

Cited By ~ 40

Author(s):

T. C. Harrington ◽

S. W. Fraedrich

Keyword(s):

South Carolina ◽

Southeastern United States ◽

Ambrosia Beetle ◽

Fungal Symbiont ◽

Laurel Wilt ◽

Xyleborus Glabratus ◽

Raffaelea Lauricola ◽

Redbay Ambrosia Beetle ◽

Yeast Phase ◽

Isolated Species

The laurel wilt pathogen, Raffaelea lauricola, is a fungal symbiont of the redbay ambrosia beetle, Xyleborus glabratus, which is native to Asia and was believed to have brought R. lauricola with it to the southeastern United States. Individual X. glabratus beetles from six populations in South Carolina and Georgia were individually macerated in glass tissue grinders and serially diluted to quantify the CFU of fungal symbionts. Six species of Raffaelea were isolated, with up to four species from an individual adult beetle. The Raffaelea spp. were apparently within the protected, paired, mandibular mycangia because they were as numerous in heads as in whole beetles, and surface-sterilized heads or whole bodies yielded as many or more CFU as did nonsterilized heads or whole beetles. R. lauricola was isolated from 40 of the 41 beetles sampled, and it was isolated in the highest numbers, up to 30,000 CFU/beetle. Depending on the population sampled, R. subalba or R. ellipticospora was the next most frequently isolated species. R. arxii, R. fusca, and R. subfusca were only occasionally isolated. The laurel wilt pathogen apparently grows in a yeast phase within the mycangia in competition with other Raffaelea spp.

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Laurel Wilt: Current and Potential Impacts and Possibilities for Prevention and Management

Forests ◽

10.3390/f12020181 ◽

2021 ◽

Vol 12 (2) ◽

pp. 181

Author(s):

Rabiu O. Olatinwo ◽

Stephen W. Fraedrich ◽

Albert E. Mayfield

Keyword(s):

United States ◽

Tree Mortality ◽

The United States ◽

Persea Americana ◽

Laurel Wilt ◽

Important Species ◽

Invasive Insects ◽

Raffaelea Lauricola ◽

Redbay Ambrosia Beetle ◽

The Impact

In recent years, outbreaks of nonnative invasive insects and pathogens have caused significant levels of tree mortality and disturbance in various forest ecosystems throughout the United States. Laurel wilt, caused by the pathogen Raffaelea lauricola (T.C. Harr., Fraedrich and Aghayeva) and the primary vector, the redbay ambrosia beetle (Xyleborus glabratus Eichhoff), is a nonnative pest-disease complex first reported in the southeastern United States in 2002. Since then, it has spread across eleven southeastern states to date, killing hundreds of millions of trees in the plant family Lauraceae. Here, we examine the impacts of laurel wilt on selected vulnerable Lauraceae in the United States and discuss management methods for limiting geographic expansion and reducing impact. Although about 13 species belonging to the Lauraceae are indigenous to the United States, the highly susceptible members of the family to laurel wilt are the large tree species including redbay (Persea borbonia (L.) Spreng) and sassafras (Sassafras albidum (Nutt.) Nees), with a significant economic impact on the commercial production of avocado (Persea americana Mill.), an important species native to Central America grown in the United States. Preventing new introductions and mitigating the impact of previously introduced nonnative species are critically important to decelerate losses of forest habitat, genetic diversity, and overall ecosystem value.

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An Acaromyces Species Associated with Bark Beetles from Southern Pine Has Inhibitory Properties Against Raffaelea lauricola, the Causal Pathogen of Laurel Wilt Disease of Redbay

Plant Health Progress ◽

10.1094/php-06-19-0039-rs ◽

2019 ◽

Vol 20 (4) ◽

pp. 220-228 ◽

Cited By ~ 1

Author(s):

Rabiu Olatinwo ◽

Stephen Fraedrich

Keyword(s):

Secondary Metabolites ◽

Loblolly Pine ◽

Spore Germination ◽

Bark Beetles ◽

Dna Analysis ◽

The United States ◽

Malt Extract ◽

Laurel Wilt ◽

Raffaelea Lauricola ◽

Redbay Ambrosia Beetle

Laurel wilt is a destructive disease of redbay (Persea borbonia) and other species in the laurel family (Lauraceae). It is caused by Raffaelea lauricola, a fungal symbiont of the redbay ambrosia beetle, Xyleborus glabratus (Coleoptera: Curculionidae), cointroduced into the United States around 2002. During assessments of fungi associated with bark beetles from loblolly pine, an unknown fungus was isolated that appeared to have broad-spectrum antifungal activities. In this study, we identified the unknown fungus and determined the inhibitory effect of its secondary metabolites on R. lauricola. DNA analysis identified the fungus as Acaromyces ingoldii (GenBank accession no. EU770231). Secondary metabolites produced by the A. ingoldii completely inhibited R. lauricola mycelial growth on potato dextrose agar (PDA) plates preinoculated with A. ingoldii and reduced R. lauricola growth significantly on malt extract agar plates preinoculated with A. ingoldii. R. lauricola isolates inoculated on PDA plates 7 days after A. ingoldii were completely inhibited with no growth or spore germination. Direct evaluation of A. ingoldii crude extract on R. lauricola spores in a multi-well culture plate assay showed inhibition of spore germination at 10% and higher concentrations. Secondary metabolites from A. ingoldii could be potentially useful in managing the future spread of laurel wilt.

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