Xylosandrus

Reitter, 1913

Species Guides

4

Xylosandrus is a of ambrosia beetles in the Scolytinae, Curculionidae, containing approximately 54 globally. The type species is Xyleborus morigerus (Blandford, 1894). Species in this genus are fungus-farming beetles that excavate gallery chambers in wood, introduce symbiotic fungi, and feed on fungal growth rather than wood tissue. Several species, including X. crassiusculus and X. germanus, have become pests of ornamental and fruit trees in North America and elsewhere.

Xylosandrus germanus by (c) Katja Schulz, some rights reserved (CC BY), uploaded by Katja Schulz. Used under a CC-BY license.Xylosandrus germanus by (c) Katja Schulz, some rights reserved (CC BY), uploaded by Katja Schulz. Used under a CC-BY license.Xylosandrus germanus by (c) Katja Schulz, some rights reserved (CC BY). Used under a CC-BY license.

Pronunciation

How to pronounce Xylosandrus: /ˌzaɪlɔˈsændrəs/

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Identification

in Xylosandrus can be distinguished from other ambrosia beetle by features of the mycangia (internal fungus-storing organs), though specific morphological characters distinguishing the genus require microscopic examination. Xylosandrus germanus is known as the black stem borer; X. crassiusculus is called the granulate ambrosia beetle. Micro-CT scanning has been used to visualize the three-dimensional structure of mycangia and associated musculature in X. amputatus.

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Distribution

The has a global distribution with native ranges in Asia. Xylosandrus germanus occurs in Europe (Austria, Belgium, France, Germany, Hungary, Italy, Russia, Slovenia, Switzerland), Asia (China, Japan, Korea Republic, Taiwan, Vietnam), North America (Canada, USA), and Oceania (New Zealand). Xylosandrus crassiusculus has been recorded in North America (USA), Central America and Caribbean, South America (Argentina, Brazil, French Guiana, Uruguay), and Oceania (Australia, New Zealand, Papua New Guinea, Samoa). Xylosandrus compactus occurs in Asia (India, Indonesia, Japan, Malaysia, Philippines, Sri Lanka, Taiwan, Thailand, Vietnam), Africa (Benin, Cameroon, Ghana, Kenya, Madagascar, Nigeria, Tanzania, Uganda), North America (USA), Central America and Caribbean, and Oceania (Fiji, Papua New Guinea, Samoa).

Diet

in this are xylomycetophagous, feeding primarily on symbiotic fungi cultivated within wood galleries rather than on wood itself. The beetles transport fungal spores in specialized mycangia and inoculate gallery walls with fungi that serve as larval food.

Host Associations

Behavior

Ambrosia beetles in this excavate gallery chambers in tree tissue, introduce symbiotic filamentous fungi, and rear offspring that consume the fungi as food. Stressed trees release ethanol, which attracts ambrosia beetle attack. In North Carolina apple orchards, X. germanus and X. crassiusculus were extracted from declining trees, comprising 34% and 26% of identified specimens respectively.

Ecological Role

in this function as fungus-farmers that symbiotic fungi into wood, creating microhabitats for fungal . In North Carolina apple orchards, 62 fungal species from 31 genera were associated with ambrosia beetle galleries, including Ambrosiella (symbiotic with X. germanus and X. crassiusculus), Chaetomium, Fusarium, Botryosphaeria, and Diaporthe. The beetles may contribute to tree decline but are not sole causative agents; abiotic stressors such as drought and rapid temperature changes facilitate both attack and fungal .

Human Relevance

Several are economically significant pests. Xylosandrus crassiusculus and X. germanus have long been pests of ornamental trees in North America and have more recently infested fruit trees. Xylosandrus compactus causes serious damage to economically valuable plants including coffee, cocoa, avocado, and tea worldwide. In 1995, X. germanus caused significant damage to stored Norway spruce and fir round timber in Europe; conventional used against other timber pests showed insufficient effect.

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