Derodontidae

LeConte, 1861

tooth-necked fungus beetles

Genus Guides

3

is a small of beetles comprising 42 in 4 and 3 . Members are commonly known as tooth-necked fungus beetles due to the spiny pronotal margins found in most genera, though the genus Laricobius lacks these spines. The family is notable for possessing two ocelli on the , an unusual trait among beetles. The genus Laricobius has gained significant attention as a agent for adelgids threatening hemlock forests in North America.

Derodontus esotericus by no rights reserved, uploaded by Ken Kneidel. Used under a CC0 license.Laricobius nigrinus by (c) Evan M. Raskin, some rights reserved (CC BY), uploaded by Evan M. Raskin. Used under a CC-BY license.Laricobius erichsonii by (c) Sandy Rae, some rights reserved (CC BY). Used under a CC-BY license.

Pronunciation

How to pronounce Derodontidae: /dɛɹoʊˈdɒntɪdiː/

These audio files are automatically generated. While they are not always 100% accurate, they are a good starting point.

Identification

The combination of small size (2–6 mm), presence of two ocelli on the , and spiny pronotal margins distinguishes most from other . Laricobius lack pronotal spines but retain the diagnostic ocelli. The family can be separated from related Bostrichoidea by these ocelli and pronotal characteristics. Larval stages of Laricobius are difficult to distinguish from each other, requiring molecular methods for accurate identification to species.

Images

Habitat

varies by . Laricobius are associated with coniferous forests, particularly hemlock (Tsuga) stands infested with adelgids. Derodontus species inhabit well-preserved natural forest habitats and are found on fungi. The occupies both native forest and urban environments where trees occur.

Distribution

Holarctic distribution. Europe: 1 (Laricobius erichsonii). North America: 3 species of Laricobius (L. nigrinus, L. rubidus, plus others), plus Derodontus and other . Asia: 17 species, concentrated in south-eastern Asia and the Himalaya. Laricobius nigrinus is native to western North America (Pacific Northwest) and has been introduced to the eastern United States. Laricobius osakensis is native to Japan. Fossil genus Juropeltastica is known from the Middle Jurassic (~163 million years old) Daohugou Beds of China.

Seasonality

Laricobius exhibit seasonal activity synchronized with their adelgid prey. undergo aestival coinciding with diapausing first-instar adelgid sistens. Adult activity, oviposition, and larval development resume in synchrony with prey development stages. Timing varies geographically: adelgid sistens matures 2–3 months earlier in British Columbia than in Virginia and Connecticut.

Diet

Varies by . Laricobius are of adelgids (Adelgidae), including Adelges tsugae (hemlock woolly adelgid), Adelges piceae (balsam woolly aphid), and Pineus strobi. Derodontus species are mycophagous, feeding on fungi including slime molds. Some feed on oyster mushrooms (Pleurotus).

Host Associations

Life Cycle

Complete with , larva, pupa, and stages. Laricobius larvae develop through multiple instars, feeding on adelgid eggs and adults. Larval development is synchronized with oviposition by adelgid sistens adults. occurs in soil or litter. Adults emerge and may undergo aestival during summer months when prey are in diapause.

Behavior

Laricobius are active that seek out adelgid colonies on trees. and larvae feed on all life stages of adelgids. Laricobius nigrinus and L. osakensis orient toward host tree odors and adelgid odors in studies, demonstrating chemotactic location of prey. Adults fly and disperse to locate new host trees. Some species exhibit phoretic mite associations, with mites hitchhiking on beetles without causing harm.

Ecological Role

of adelgids in forest . Laricobius serve as natural enemies that help regulate adelgid . In their native ranges, they contribute to natural of adelgid populations on conifers. In eastern North America, introduced Laricobius species are being evaluated and deployed as biological control agents to mitigate hemlock woolly adelgid damage and preserve hemlock ecosystem functions. by L. nigrinus has been shown to significantly impact HWA sistens and promote new shoot production on hemlock trees.

Human Relevance

The Laricobius is significant for of forest pests. Laricobius nigrinus was first released in 2003 and L. osakensis in 2012 for control of hemlock woolly adelgid in eastern North America. Over 400,000 beetles have been released from Georgia to Maine. Establishment has been confirmed in forest and urban environments. These biological control efforts aim to preserve eastern hemlock forests, which provide critical for native bird and maintain functions on steep slopes where chemical control is impractical. Derodontus species are rarely encountered and have no significant economic impact.

Similar Taxa

More Details

Taxonomic composition

The comprises 3 : Derodontinae ( Derodontus, 11 ), Laricobiinae (genera Laricobius with 23 species, Nothoderodontus with 6 species), and Peltasticinae (genus Peltastica, 2 species). A fossil genus Juropeltastica is known from the Middle Jurassic of China.

Phylogenetic groups within Laricobius

Two broad clades exist: one confined to south-eastern Asia and the Himalaya with shortened body form and narrow pronotum lacking explanate margins, and a more widespread Holarctic group that is more elongate with transverse, fully explanate pronotum. Four Asian lack ocelli.

Environmental DNA monitoring

Recent research has developed eDNA assays using CO1 gene sequences to detect and differentiate Laricobius in environmental (soil, water, plant matter), aiding monitoring of establishment and spread.

Tags

Sources and further reading