Xyleborus affinis

Xyleborus affinis
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Arthropoda
Class:	Insecta
Order:	Coleoptera
Infraorder:	Cucujiformia
Family:	Curculionidae
Genus:	Xyleborus
Species:	X. affinis
Binomial name
	Xyleborus affinis; Eichhoff, 1868

Last updated March 22, 2024

Xyleborus affinis, the sugarcane shot-hole borer, is a species of ambrosia beetle in the family Curculionidae. It is found on all continents with woodlands and is one of the most widespread ambrosia beetles internationally,^[1] primarily in areas with humid tropical climates like Florida.^[2]^[3]^[4] Like other ambrosia beetles, Xyleborus affinis is attracted to dead fallen logs in early stages of decay. Due to the presence of X. affinis on moist timber, this species is mistakenly believed to be the cause of tree death.^[1] However, there is insufficient evidence to support their presence as a causal factor. Rather, these beetles are believed to target and accelerate the decay process of trees that are already deteriorated and weak.^[1]

Similar to other species of ambrosia beetles, Xyleborus affinis lives in symbiosis with ambrosia fungi and dig tunnels (formally known as galleries) into the xylem of decaying trees where the fungus is then grown.^[1] Female eggs are laid in these fungus-lined galleries and use the fungus as a food source.^[1]

Temperature is a determining factor for how sexually dimorphic this species develops to be, with those that grew under high temperatures having less pronounced sexually dimorphic traits than those that grew under lower temperature conditions.^[5]

Subspecies

These two subspecies belong to the species Xyleborus affinis:

Xyleborus affinis affinis
Xyleborus affinis mascarensisEichhoff, 1878

Range

In the United Status, Xyleborus affinis is found all over the east coast, ranging from Michigan in the north to Florida in the south and even to Texas in the west.^[1] This species is also found in regions of South and Central America, such as the Antilles, Belize, Costa Rica, El Salvador, Guatemala, Honduras, Mexico, Nicaragua, Panama, and Argentina. The species has also spread into Africa, Asia, Australia, Europe, and the Pacific Islands such as Hawaii.^[6]

Xyleborus affinis originates in the American tropics, and is especially abundant in tropical climates like Florida,^[6]^[7] it currently inhabits the majority of international tropical and subtropical regions.^[1] Similar to other beetle species that inoculate wood, Xyleborus affinis is easily transmitted via wood distribution and international trade.^[1]

Characteristics

Adults

This species is yellowish to reddish brown in color and resembles the morphology of other Xyleborus species with its elongated, cylindrical body. Xyleborus adults are sexually dimorphic , which means that the size, shape, and structure of bodily characteristics differ between males and females.^[1] Females are, on average, 2.0–2.7 mm long and are larger than males, which are typically 1.7–2.0 mm long.^[1] In contrast to females, males do not have wings, have smaller eyes and antennae, and are less numerous in the population.^[1] Although the female to male sex ratio has been reported as 14 to 1 in a study by Roeper et al. (2017), it widely varies and has not yet definitively been identified.^[8]

This species very closely resembles Xyleborus perforans Wollaston and Xyleborus volvulus Fabricius, both of which are found in Florida.^[1]Xyleborus affinis is unique based on the downward slant of its abdomen at the end of its elytra.^[1] In Xyleborus affinis, the surface of this declivity is dull and nontransparent, whereas it is shiny and smooth in the other two species.^[1]

Eggs

The eggs are ivory-colored, ellipsoidal, and shiny and vary in length from 0.6 to 1.0 mm with an average of 0.718 mm.^[1] Females lay eggs in groups of two to four along the fungus-lined horizontal galleries that extend horizontally away from the main vertical tunnels.^[1] At 29 °C, eggs can be laid anywhere from three to 27 days after introduction into the host log.^[9]

Larvae

Larvae are white, have a slightly bent shape, and do not have legs.^[1] At 29 °C, larvae take 7–14 days to hatch, whereas they take14–35 days to hatch at 22–24 °C.^[1] Larvae are nourished solely from the symbiotic fungus inhabiting the galleries.^[9]

Pupae

Pupae are initially white, but they become light brown in color just before they appear as adults.^[1] On average, males are 2.0 mm long and shorter than females, which are 2.7 mm long.^[1] At 29 °C, it takes larvae 11-23 days to mature into pupae, whereas it takes 21–35 days at 22–24 °C.^[1] At 29 °C, it takes adults 18-35 to surface, whereas it takes 27–35 days at 22–24 °C.^[9]

Ecology

Hosts

Xyleborus affinis is found in natural woodlands and inhabits damp logs on the ground.^[1] Even though this species is one of the most common ambrosia beetles found in wooded regions, its population size is often grossly underestimated.^[1] The beetles inoculate large trees in a series of stages, first inhabiting dead phloem and then moving onto the xylem, which is where most eggs are laid.^[1]

Although Xyleborus affinis is not particular about choosing the species of its host tree, it is selective based on how deteriorated and damp the fallen log is.^[1] These beetles favor large and moist pieces of wood that are early on in the decay process, which is believed to be due to the symbiotic fungus' moisture requirement for survival. ^[1] As a result, these beetles are especially plentiful in logs partially immersed in water or lying on moist ground.^[1]

Symbiosis

The female beetles have a specialized pocket inside their mouths, known as mycangium, where they maintain a population of fungal symbiont.^[1] This fungus gets injected inside the galleries the females create, allowing for a mutualistic symbiosis.^[1] Until they become adults, larvae will continue to feed on the spore-containing fungi.^[10]

Ethanol is the most popularly used chemicals that attracts ambrosia beetles and is used in observational studies.^[1] However, Xyleborus affinis is not strongly drawn toward ethanol and is thus more difficult to monitor.^[1]

Reproduction

Like all other Xyleborus beetles, Xyleborus affinis is haplodiploid.^[1] In this sex-determination system, females develop from fertilized eggs with a diploid set of DNA from both their mother and father, whereas males develop from unfertilized eggs and are born haploid, containing DNA from only their mother. Additionally, Xyleborus affinis is inbred.^[1] Because males remain confined to their original host tree and their only purpose is to fertilize nearby females, many of these eggs are their sisters.^[1] After becoming adults, females will either continue reproducing in the host log or, if the current log is too decomposed, will look for a new host.^[1] In contrast to most ambrosia beetles in which each generation seeks a new host, Xyleborus affinis' ability to maintain consecutive populations in the same log is atypical.^[1]

Sexual Dimorphism

In the genus

The phenomenon of sexual dimorphism within Xyleborus genus, particularly in terms of size and distinct categorical traits, has been thoroughly established.^[11]^[12]^[13]^[14]^[15] In research conducted by Ospina-Garcés, Sandra M., et al. (2021), an analysis was carried out to assess the differences in size and shape of the elytra and pronotum between sexes.^[16] The findings indicated that sex does not affect how size influences shape differences in these body parts, with the degree of shape variation attributable to similar centroid size between the sexes and the two structures examined.^[16] A significant correlation was identified between the shapes of the pronotum and elytra, suggesting a coordinated development of body shape in these beetles.^[16] Furthermore, while both the elytra and pronotum exhibit sexual dimorphism in size and shape, this difference is more pronounced in the shape of the pronotum compared to the elytra.^[16] The study also revealed contrasting patterns of shape variation in relation to centroid size for each structure: a negative allometric trend was observed for elytra shape from males to females, where as a positive allometric trend was observed for pronotum shape from males to females.^[16]

In the species

The findings reveal that structural differences in the elytra and pronotum vary in a coordinated manner.^[16] However, the pronotum demonstrates greater variation in shape and therefore a higher degree of sexual dimorphism in both size and shape compared to the elytra.^[16] Prior studies, including observations in X. affinis, have noted sexual size dimorphism in the pronotum, with females displaying a larger size than males when measured using traditional methods of length and width.^[12]

An additional study by Ospina-Garcés, Sandra M., et al. (2021) detected a notable sexual dimorphism in X. affinis, with males possessing shorter and wider mandibles compared to females, as well as exhibiting an apophysis on the external contour of the mandible.^[5] This dimorphism is thought to be influenced by the species' haplodiploid sex determination system and prevalence of inbreeding, as well as the fact that only females spread out and colonize.^[5]

Effect of temperature

The same study evaluated the effect of different temperatures on the development of head size and mandible shape throughout the growth stages of X. affinis.^[5] It suggests that the temperature in which the larvae grow contributes to head size variation, where a narrower mandible size range was observed at higher temperatures (width: 0.12–0.40 mm), while lower temperatures allowed for a wider range of mandible sizes (width: 0.11–0.49 mm).^[5] It was also found that mandible size variation was linked to changes in larval instars through four distinct ontogenesis stages, regardless of the temperature conditions.^[5]

Regarding the extent and pattern of sexual dimorphism in mandible shape and size, the study found that the differences between sexes were minimized at higher temperatures, whereas more variable patterns of dimorphism were observed at lower and medium temperatures.^[5] The most pronounced disparities in mandible shape between sexes were recorded at 23 °C, and the largest size differences at 26 °C.^[5] These findings suggest that extreme temperatures outside optimal temperature ranges (23 °C and 29 °C) may induce phenotypic variations in mandible shape between sexes, potentially affecting their functionality.^[5]

Damage

Although the inoculation of Xyleborus affinis on fallen logs can accelerate the decay process, these beetles typically seek out weak and injured timber that are already deteriorating.^[1] As a result, the presence of these beetles alone is typically not believed to cause decomposition.^[1]

Xyleborus affinis is gaining attention in the context of plant diseases based on its ability to transmit disease-causing fungi, such as the causal agent of laurel wilt disease, between different plant species.^[1] When these beetles burrow into trees in the Laurel family, they transfer the fungal seeds to the trees.^[17] These spores proceed to contaminate the xylem bu cutting off the vascular system, leading to wilting and mortality in as quick as weeks to months after inoculation.^[17]

Xyleborus affinis can also compromise the structural integrity of freshly cut natural wood more than any other ambrosia species because of its family arrangement and labor division.^[1] In most ambrosia beetle species, the mother is solely responsible for burrowing galleries, but in Xyleborus affinis, the daughter females help expand the tunnel system as well.^[1] This allows numerous gallery systems to be formed, both superficially and deep within the xylem.^[1]

Related Research Articles

The Curculionidae are a family of weevils, commonly called snout beetles or true weevils. They are one of the largest animal families with 6,800 genera and 83,000 species described worldwide. They are the sister group to the family Brentidae.

Ambrosia beetles are beetles of the weevil subfamilies Scolytinae and Platypodinae, which live in nutritional symbiosis with ambrosia fungi. The beetles excavate tunnels in dead or stressed trees in which they cultivate fungal gardens, their sole source of nutrition. After landing on a suitable tree, an ambrosia beetle excavates a tunnel in which it releases its fungal symbiont. The fungus penetrates the plant's xylem tissue, extracts nutrients from it, and concentrates the nutrients on and near the surface of the beetle gallery. Ambrosia fungi are typically poor wood degraders, and instead utilize less demanding nutrients. Symbiotic fungi produce and detoxify ethanol, which is an attractant for ambrosia beetles and likely prevents growth of antagonistic pathogens and selects for other beneficial symbionts. The majority of ambrosia beetles colonize xylem of recently dead trees, but some attack stressed trees that are still alive, and a few species attack healthy trees. Species differ in their preference for different parts of trees, different stages of deterioration, and in the shape of their tunnels ("galleries"). However, the majority of ambrosia beetles are not specialized to any taxonomic group of hosts, unlike most phytophagous organisms including the closely related bark beetles. One species of ambrosia beetle, Austroplatypus incompertus exhibits eusociality, one of the few organisms outside of Hymenoptera and Isoptera to do so.

<span class="mw-page-title-main">Bark beetle</span> Subfamily of beetles

A bark beetle is the common name for the subfamily of beetles Scolytinae. Previously, this was considered a distinct family (Scolytidae), but is now understood to be a specialized clade of the "true weevil" family (Curculionidae). Although the term "bark beetle" refers to the fact that many species feed in the inner bark (phloem) layer of trees, the subfamily also has many species with other lifestyles, including some that bore into wood, feed in fruit and seeds, or tunnel into herbaceous plants. Well-known species are members of the type genus Scolytus, namely the European elm bark beetle S. multistriatus and the large elm bark beetle S. scolytus, which like the American elm bark beetle Hylurgopinus rufipes, transmit Dutch elm disease fungi (Ophiostoma). The mountain pine beetle Dendroctonus ponderosae, southern pine beetle Dendroctonus frontalis, and their near relatives are major pests of conifer forests in North America. A similarly aggressive species in Europe is the spruce ips Ips typographus. A tiny bark beetle, the coffee berry borer, Hypothenemus hampei is a major pest on coffee plantations around the world.

Xyleborus glabratus, the redbay ambrosia beetle, is a type of ambrosia beetle invasive in the United States. It has been documented as the primary vector of Raffaelea lauricola, the fungus that causes laurel wilt, a disease that can kill several North American tree species in the family Lauraceae, including redbay, sassafras, and avocado.

Austroplatypus incompertus is a species of ambrosia beetle belonging to the true weevil family, native to Australia, with a verified distribution in New South Wales and Victoria. It forms colonies in the heartwood of Eucalyptus trees and is the first beetle to be recognized as a eusocial insect. Austroplatypus incompertus is considered eusocial because groups contain a single fertilized female that is protected and taken care of by a small number of unfertilized females that also do much of the work. The species likely passed on cultivated fungi to other weevils.

Ips is a genus of beetles in the family Curculionidae, the true weevils. They are bark beetles, members of the subfamily Scolytinae. Species are distributed throughout the Northern Hemisphere. Some are known as introduced species in Australia and Africa. Many species are pests of forest trees, especially pines and spruces. They are known commonly as engraver beetles, ips engraver beetles, and pine engravers.

Platypus apicalis, known by its common name the New Zealand pinhole boring beetle, is a wood-boring beetle endemic to New Zealand and found throughout the North and South Island in a range of environments.

<i>Euwallacea fornicatus</i> Species of beetle

Euwallacea fornicatus is a species complex consisting of multiple cryptic species of ambrosia beetles, known as an invasive species in California, Israel and South Africa. The species has also been unintentionally introduced into exotic greenhouses in several European countries. As the rest of the ambrosia beetles, E. fornicatus larvae and adults feed on a symbiotic fungus carried in a specific structure called mycangium. In E. fornicatus, the mycangium is located in the mandible. The combination of massive numbers of beetles with the symbiotic fungus kills trees, even though the fungus alone is a weak pathogen.

Xylosandrus compactus is a species of ambrosia beetle. Common names for this beetle include black twig borer, black coffee borer, black coffee twig borer and tea stem borer. The adult beetle is dark brown or black and inconspicuous; it bores into a twig of a host plant and lays its eggs, and the larvae create further tunnels through the plant tissues. These beetles are agricultural pests that damage the shoots of such crops as coffee, tea, cocoa and avocado.

Xylosandrus germanus, known generally as the alnus ambrosia beetle or black stem borer, is a species of ambrosia beetle in the family Curculionidae. X. germanus poses challenges in woody ornamental species and orchard crops such as apples and pecan. Furthermore, X. germanus is recognized or suspected to act as a vector for plant pathogens to varying extents, potentially leading to the decline of trees. The black stem borer is native to eastern Asia, but is an invasive species in Europe and North America. This species carries and feeds on associated ambrosia fungus, Ambrosiella grosmanniae.

Xyleborinus saxesenii, commonly known as the fruit-tree pinhole borer, is a species of ambrosia beetle in the family Curculionidae. It is native to the Palaearctic region but has been introduced in many locations, including North America. X. saxesenii typically live in freshly dead wood, but it has also been reported to attack live trees. Such attacks on live trees may lead to economic damage.

Xyleborus dispar is a species of bark beetle commonly called the Pear blight beetle, or the European shothole borer. It is an invasive species in North America, and can be a pest in orchards and forests throughout its range.

Euwallacea interjectus is a species of Euwallacea fornicatus beetle native to Asia but has been introduced to the Western hemisphere over the last century.

Sueus niisimai is a species of weevil found in India, Sri Lanka, China, Japan, Taiwan, Korea, Malaysia and Indonesia. It is also found in Australia and Fiji, presumably introduced.

Debus emarginatus, is a species of weevil widely distributed throughout the Old World tropics.

Xylosandrus morigerus, is a species of weevil widespread throughout Afrotropical, Australian, Neotropical, Oceania and Oriental regions. It is also introduced to Palearctic regional countries.

Euwallacea perbrevis, commonly known as tea shot-hole borer, is a species of weevil native to South and South-East Asia through to Australia, but introduced to Western countries.

Arixyleborus malayensis, is a species of weevil found in India, Sri Lanka, China, Japan, Malaysia, Vietnam and Indonesia. This is the only species of Arixyleborus found in Japan and China.

Diuncus haberkorni, is a species of weevil found in India, Sri Lanka, Bangladesh, Taiwan, Java, Japan, Malaysia, New Guinea, South Korea, Taiwan, Thailand, and Vietnam. It is also imported to African countried such as South Africa, and Tanzania.

References

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 "EENY 627/IN1094: An Ambrosia Beetle Xyleborus affinis Eichhoff (1868) (Insecta: Coleoptera: Curculionidae: Scolytinae)". Ask IFAS - Powered by EDIS. Retrieved 2024-02-26.
↑ "Xyleborus affinis Report". Integrated Taxonomic Information System. Retrieved 2019-09-23.
↑ "Xyleborus affinis". GBIF. Retrieved 2019-09-23.
↑ "Xyleborus affinis species Information". BugGuide.net. Retrieved 2019-09-23.
1 2 3 4 5 6 7 8 9 Ospina-Garcés, Sandra M.; Ibarra-Juarez, Luis A.; Escobar, Federico; Lira-Noriega, Andrés (2021-03-01). "Growth temperature effect on mandibles' ontogeny and sexual dimorphism in the ambrosia beetle Xyleborus affinis (Curculionidae: Scolytinae)". Arthropod Structure & Development. 61: 101029. doi:10.1016/j.asd.2021.101029. ISSN 1467-8039.
1 2 Rabaglia, Robert J.; Dole, Stephanie A.; Cognato, Anthony I. (2006-11-01). "Review of American Xyleborina (Coleoptera: Curculionidae: Scolytinae) Occurring North of Mexico, with an Illustrated Key". Annals of the Entomological Society of America. 99 (6): 1034–1056. doi:10.1603/0013-8746(2006)99[1034:roaxcc]2.0.co;2. ISSN 0013-8746.
↑ "T.H. Atkinson Bark and Ambrosia beetle pages: Home". barkbeetles.info. Retrieved 2024-02-26.
↑ Roeper, Richard A.; Bunce, Mark A; Harlan, John E; Bowker, Richard G (2017-04-11). "Observations of Xyleborus affinis Eichhoff (Coleoptera:Curculionidae:Scolytinae) in Central Michigan". The Great Lakes Entomologist. 48 (3). doi:10.22543/0090-0222.1015. ISSN 0090-0222.
1 2 3 Roeper, Richard A.; Allen, Michael; Hutchinson, Teresa; Quidot, Corrina; Bunce, Mark (2017-04-11). "Gallery Characteristics and Life History of the Ambrosia Beetle Trypodendron betulae (Coleoptera: Curculionidae: Scolytinae) in Birch". The Great Lakes Entomologist. 48 (3). doi:10.22543/0090-0222.1022. ISSN 0090-0222.
↑ Carrillo, D.; Duncan, R. E.; Ploetz, J. N.; Campbell, A. F.; Ploetz, R. C.; Peña, J. E. (2013-05-10). "Lateral transfer of a phytopathogenic symbiont among native and exotic ambrosia beetles". Plant Pathology. 63 (1): 54–62. doi:10.1111/ppa.12073. ISSN 0032-0862.
↑ Norris, Dale M.; Chu, Hsien-Ming (1970-07-15). "Nutrition of Xyleborus ferrugineus. II. A Holidic Diet for the Aposymbiotic Insect". Annals of the Entomological Society of America. 63 (4): 1142–1145. doi:10.1093/aesa/63.4.1142. ISSN 0013-8746.
1 2 Kingsolver, Joel G.; Norris, Dale M. (1977). "External morphology of Xyleborus ferrugineus (Fabr.) (Coleoptera: Scolytidae). I. Head and prothorax of adult males and females". Journal of Morphology. 154 (1): 147–156. doi:10.1002/jmor.1051540110. ISSN 0362-2525.
↑ Mizuno, T.; Kajimura, H. (2002). "Reproduction of the ambrosia beetle, Xyleborus pfeili (Ratzeburg) (Col., Scolytidae), on semi-artificial diet". Journal of Applied Entomology. 126 (9): 455–462. doi:10.1046/j.1439-0418.2002.00691.x. ISSN 0931-2048.
↑ Brar, Gurpreet S.; Capinera, John L.; Kendra, Paul E.; McLean, Stephen; Peña, Jorge E. (2013). "Life Cycle, Development, and Culture of Xyleborus glabratus (Coleoptera: Curculionidae: Scolytinae)". Florida Entomologist. 96 (3): 1158–1167. doi: 10.1653/024.096.0357 . ISSN 0015-4040.
↑ Castro, Jessenia; Smith, Sarah M; Cognato, Anthony I; Lanfranco, Dolly; Martinez, Malena; Guachambala, Marcelino (2019-01-03). "Life Cycle and Development of Coptoborus ochromactonus (Coleoptera: Curculionidae: Scolytinae), a pest of balsa". Journal of Economic Entomology. 112 (2): 729–735. doi:10.1093/jee/toy403. ISSN 0022-0493.
1 2 3 4 5 6 7 Ospina-Garcés, Sandra M.; Ibarra-Juarez, Luis Arturo; Escobar, Federico; Lira-Noriega, Andrés (2021). "Evaluating Sexual Dimorphism in the Ambrosia Beetle Xyleborus affinis (Coleoptera: Curculionidae) Using Geometric Morphometrics". Florida Entomologist. 104 (2): 61–70. doi: 10.1653/024.104.0201 . ISSN 0015-4040.
1 2 "Laurel Wilt | Forestry and Natural Resources". forestry.ca.uky.edu. Retrieved 2024-02-26.