''Xyleborus glabratus'', the redbay ambrosia beetle, is a type of

ambrosia beetle Ambrosia beetles are beetles of the weevil subfamilies Scolytinae and Platypodinae (Coleoptera, Curculionidae), which live in nutritional symbiosis with ambrosia fungi. The beetles excavate tunnels in dead or stressed trees into which they introduc ...

invasive in the United States. It has been documented as the primary

vector Vector most often refers to: * Euclidean vector, a quantity with a magnitude and a direction * Disease vector, an agent that carries and transmits an infectious pathogen into another living organism Vector may also refer to: Mathematics a ...

of '' Raffaelea lauricola'', the fungus that causes

laurel wilt Laurel wilt, also called laurel wilt disease, is a vascular disease that is caused by the fungus ''Raffaelea lauricola'', which is transmitted by the invasive redbay ambrosia beetle, ''Xyleborus glabratus''. The disease affects and kills membe ...

, a disease that can kill several North American tree species in the family

Lauraceae Lauraceae, or the laurels, is a plant Family (biology), family that includes the bay laurel, true laurel and its closest relatives. This family comprises about 2850 known species in about 45 genus (biology), genera worldwide. They are dicotyled ...

, including redbay,

sassafras ''Sassafras'' is a genus of three extant and one extinct species of deciduous trees in the family Lauraceae, native to eastern North America and eastern Asia.Wolfe, Jack A. & Wehr, Wesley C. 1987. The sassafras is an ornamental tree. "Middle Eo ...

, and

avocado The avocado, alligator pear or avocado pear (''Persea americana'') is an evergreen tree in the laurel family (Lauraceae). It is native to Americas, the Americas and was first domesticated in Mesoamerica more than 5,000 years ago. It was priz ...

Distribution

''Xyleborus glabratus'' is native to Asia, including

India India, officially the Republic of India, is a country in South Asia. It is the List of countries and dependencies by area, seventh-largest country by area; the List of countries by population (United Nations), most populous country since ...

Japan Japan is an island country in East Asia. Located in the Pacific Ocean off the northeast coast of the Asia, Asian mainland, it is bordered on the west by the Sea of Japan and extends from the Sea of Okhotsk in the north to the East China Sea ...

Myanmar Myanmar, officially the Republic of the Union of Myanmar; and also referred to as Burma (the official English name until 1989), is a country in northwest Southeast Asia. It is the largest country by area in Mainland Southeast Asia and has ...

, and

Taiwan Taiwan, officially the Republic of China (ROC), is a country in East Asia. The main geography of Taiwan, island of Taiwan, also known as ''Formosa'', lies between the East China Sea, East and South China Seas in the northwestern Pacific Ocea ...

. It was first detected in the United States in 2002, and may have arrived in wood products, packing materials or pallets. ''X. glabratus'' and laurel wilt disease have since spread through much of the

Gulf A gulf is a large inlet from an ocean or their seas into a landmass, larger and typically (though not always) with a narrower opening than a bay (geography), bay. The term was used traditionally for large, highly indented navigable bodies of s ...

and

Atlantic Coastal Plain The Atlantic Ocean is the second largest of the world's five borders of the oceans, oceanic divisions, with an area of about . It covers approximately 17% of Earth#Surface, Earth's surface and about 24% of its water surface area. During the ...

s, ranging from eastern Texas and Arkansas to North Carolina, and in 2019 they were found in Kentucky and Tennessee.

Identification

Adult

The female redbay ambrosia beetle is a small (2.1 to 2.4 mm long), black or amber-brown, cigar-shaped beetle. The dorsal surface is mostly hairless and shiny when compared to other ambrosia beetles. They can be specifically identified by characters present on the elytral declivity, including its steep and convex shape when compared to other ''Xyleborus'', and by the large size of indentations on the

elytra An elytron (; ; : elytra, ) is a modified, hardened forewing of beetles (Coleoptera), though a few of the true bugs (Hemiptera) such as the family Schizopteridae are extremely similar; in true bugs, the forewings are called hemelytra (sometime ...

Larvae and pupae

The larvae of the beetle are similar in appearance to others of the group, developing as a white and legless "worm" with an amber-colored head capsule. The pupae are whitish, exarate (with free appendages), and similar in size to the adult.

Biology

The redbay ambrosia beetle is believed to originate from Asia or southeast Asia. Males are

haploid Ploidy () is the number of complete sets of chromosomes in a cell (biology), cell, and hence the number of possible alleles for Autosome, autosomal and Pseudoautosomal region, pseudoautosomal genes. Here ''sets of chromosomes'' refers to the num ...

, smaller in size, and flightless. The beetle's biology is poorly documented, but presumed to be similar to that of other

ambrosia beetles Ambrosia beetles are beetles of the weevil subfamilies Scolytinae and Platypodinae (Coleoptera, Curculionidae), which live in nutritional symbiosis with ambrosia fungi. The beetles excavate tunnels in dead or stressed trees into which they introduc ...

, with larvae and adults feeding on the

symbiotic Symbiosis (Ancient Greek : living with, companionship < : together; and ''bíōsis'': living) is any type of a close and long-term biolo ...

fungus it carries with it, and not the wood of the host tree. The spores of the fungus are carried in

mycangia The term mycangium (pl., mycangia) is used in biology for special structures on the body of an animal that are adapted for the transport of symbiotic fungi (usually in spore form). This is seen in many xylophagous insects (e.g. horntails and bark ...

at the base of each

mandible In jawed vertebrates, the mandible (from the Latin ''mandibula'', 'for chewing'), lower jaw, or jawbone is a bone that makes up the lowerand typically more mobilecomponent of the mouth (the upper jaw being known as the maxilla). The jawbone i ...

. Larval development time takes from fifty to sixty days. Studied populations increase steadily in size until late summer and early fall without distinct population peaks, leading researchers to believe that there are overlapping generations with year-round reproduction for the insect.

History of expansion

The redbay ambrosia beetle can spread in at least two ways: one is via the beetle's natural reproduction and migration. A second way is through the sale and transport of beetle-infested wood, a result of redbay's use as firewood and for outdoor grilling. The beetle was first detected in the United States in 2002, in

Port Wentworth Port Wentworth is a city in Chatham County, Georgia, United States. The 2020 population was 10,878, more than double the population of 5,359 at the 2010 census. Port Wentworth is part of the Savannah metropolitan area. History The Georgia Gener ...

, Georgia. It has been suggested that this insect was introduced to the country on the wood of packing crates. The significance of these detections became apparent when the beetle was linked to and identified as the vector of

, a fungal disease that had been killing large numbers of redbay trees. The fungus grows throughout the

xylem Xylem is one of the two types of transport tissue (biology), tissue in vascular plants, the other being phloem; both of these are part of the vascular bundle. The basic function of the xylem is to transport water upward from the roots to parts o ...

of the tree, preventing the flow of water and nutrients throughout the plant. Host tree death can occur from four to eleven weeks after inoculation.

References

External links

* https://web.archive.org/web/20090616173240/http://www.fs.fed.us:80/r8/foresthealth/laurelwilt/index.shtml * https://web.archive.org/web/20090722014653/http://www.doacs.state.fl.us:80/pi/enpp/ento/x.glabratus.html * Mor
images

on the UF / IFAS Featured Creatures Web site

"Farewell to taco topping?" – mbrosia beetlespreads Laurel Wilt {{Taxonbar, from=Q8045345 Woodboring beetles Scolytinae Beetles of Asia Insect vectors of plant pathogens Beetles described in 1877