Asian Ambrosia Beetle (Xylosandrus crassiusculus)
Latin Name: Xylosandrus crassiusculus
Common Name: Asian Ambrosia Beetle
Appearance:
The head of Xylosandrus crassiusculus, like other species in the Xyleborini tribe, is concealed by the pronotum in dorsal view, the antennal club looks obliquely sliced, and the body usually is smooth and glossy.
The robust body, truncate elytral declivity, and non-contiguous procoxae distinguish Xylosandrus spp. from allied genera (Xyleborus, Xyleborinus, Ambrosiodmus).
Xylosandrus crassiusculus belongs to the Xyleborini tribe. Males are substantially smaller and formed differently than females, measuring just 1.5 mm long with a narrowed thorax and a “hunch-backed” look.
Females are 2.1 to 2.9 mm long, with a thick body and a rich reddish-brown mature hue that gets deeper on the elytral declivity.
Host plants:
Granulate ambrosia beetles emerge in early spring and attack soft-barked deciduous trees. The most-reported damaged North Carolina nurseries include styrax, dogwood, redbud, maple, ornamental cherry, Japanese maple, and crapemyrtle. Pecan, peach, plum, persimmon, Shumard oak, Chinese elm, golden rain tree, sweet gum, magnolia, fig, and azalea have also been identified as hosts.
Territory:
The granulate ambrosia beetle, Xylosandrus crassiusculus, is the most prevalent, imported to South Carolina from Asia in the early 1970s. Since then, it has spread throughout the Southeast. Infestations of the granulate ambrosia beetle can be distinguished by toothpick-like strands projecting up to 1.5 inches from the host plant.
Damage caused by Asian Ambrosia Beetle:
Boring can allow harmful fungi such as Fusarium spp. to enter the environment. Infested nursery stock usually dies or becomes unmarketable, and it should be destroyed or chipped to avoid the emergence of new adults. The visible indicators are wilted foliage and strands of boring dust sprouting from tiny holes. Serious assaults that result in tree mortality frequently occur during the spring leafing-out period.
Life history and Habits:
Female ambrosia beetles burrow into susceptible woody plant twigs, branches, or tiny trunks, excavating a network of tunnels in the wood or pith, introducing the symbiotic ambrosial fungus, and producing a brood. In the tunnel system dug by the female, eggs, larvae, and pupae are found together. Individual egg niches, larval tunnels, or pupal chambers do not exist. It breeds in host material ranging from 2 to 30 cm in diameter, with tiny branches and stems being the most usually targeted. Males are few, small, flightless, and likely haploid. Females mate with their brother(s) before attacking a new host. For effective reproduction, high humidity is essential. Attacks can occur on host material that seems healthy, strained, or just cut.
