Cephalallus unicolor (Gahan, 1906)

Pham, Duy Long, Chi, Nguyen Minh, Loi, Vu Van, Danh, Duong Ngoc, Vui, Nguyen Thi Kim, Hung, Pham Tien, Dinh, Le Cong, Ha, Ngoc Linh & Vitali, Francesco, 2023, Longhorn beetles as new pests for exotic plantations in Vietnam, Ecologica Montenegrina 70, pp. 188-198 : 192-194

Cephalallus unicolor damage in Pinus caribaea

First-instar larvae feed on the inner shell, while second-instar larvae feed on the stratum corneum. Then, larvae chisel into the sapwood of tree, where the wood is softer, and create zigzag or serpentine tunnels within the trunk, 8.2–14.5 mm wide and 19–36 cm long ( Fig. 4D ). Exit holes range from 10.5 to 12.5 mm in diameter. Infestation of C. unicolor targets the lower trunk of host trees, 1.5–4.5 m above the ground. C. unicolor adults start laying eggs on host trees and continue causing damage closer to the point of egg-laying until the hosts die. In case of severe infestations, the number of C. unicolor larvae in each tree reach hundred of individuals, resulting in tree mortality due to large number of larvae quickly consuming the wood inner layers and sapwood of host trees.

Severity of longhorn beetles in host plants

This study has recorded the extent of damage ( Table 2) caused by: Coptops annulipes in Acacia crassicarpa plantations in Quang Tri province (P% = 16.8%; DI = 0.41); Anagelasta apicalis (P% = 29.5%; DI = 0.85) and Desisa subfasciata (P% = 39.2%; DI = 1.16) in Eucalyptus hybrid plantations in Bac Giang province; Cephalallus unicolor in Pinus caribaea plantations in Quang Tri (P% = 24.3%; DI = 0.71). In P. caribaea plantations, about 5–6% of trees are being newly damaged each year and at the same time, trees attacked in previous years are severely damaged or die.

Figures

Figure 4. Cephalallus unicolor damage in Pinus caribaea in Quang Tri province: A, B, C. female adult; D. damaged tree with holes on the stem