Description
ORIGIN AND SPREAD. A. chinensis (CLB) and A. glabripennis (ALB) are cerambycid beetles of Asian origin, introduced in recent decades in Europe and America (ALB only). In Italy they are present in several regions. The routes of entry and spread are mainly linked to trade in materials that may contain larvae (ornamental plants, timber and wooden packaging).
HOST PLANTS They are highly polyphagous xylophagous insects whose larvae feed on the wood of many trees and shrubs. Adults gnaw the bark of apical shoots, as well as petioles and leaves. They can also attack healthy, vigorous plants. The host plants are ornamental broad-leaved trees, forestry and fruit trees, including, in particular, maples, birches, hornbeams, hazels, horse chestnuts, plane trees, elms, willows, poplars, beeches, citrus trees, roses, apple trees, pear trees and various Prunus.
Adults fly from May to August and feed in the crowns. After mating, they lay up to 100 eggs individually under the bark. The larvae dig long tunnels inside the wood and pupate near the bark. Once they have reached the adult stage, they emerge, leaving on outcropping roots, trunks or branches characteristic circular flickering holes, 1-2 cm in diameter. The entire development cycle is completed in 1-2 years, depending on climatic conditions.
MORPHOLOGY.
Adults. On average 20 to 37 mm long, bright black with pale spots on the elytra. Long antennae, with alternating light and dark bands. Males smaller than females, but with longer antennae. The two species can be distinguished by the roughness at the base of the elytra (only present in A. chinensis).
Eggs. White, 5-6 mm long, similar to grains of rice.
Larvae. Without legs, up to 60 mm long, cream-coloured with brown head.
Pupae. They are cream-white, with their appendages free from the body.
SYMPTOMATOLOGY. The greatest damage is caused by the trophic activity of the larvae. Galleries are dug in the wood at the base of the trunk and in the roots(A. chinensis) or in the highest part of the trunk and in the branches(A. glabripennis), with a reduction in the stability of the branches or the whole plant.
Main signs of presence: emission of rosura from the galleries, with accumulation at the base of the plant, and flicker holes of the adults at the base of the trunk or on the branches.
Other distinctive signs: erosions made by the adults on the crown and scars left by the females when laying their eggs on the trunk or branches (ovideposition niches). An affected tree shows desiccation of portions of the crown and progressive decay until death, which occurs within a few years.
PEST CONTROL. A. chinensis and A. glabripennis are priority quarantine pests for the EU, as they are considered very dangerous due to the extensive damage they can cause. Already reported in Europe and Italy, compulsory control measures are in force for both and enhanced prevention and surveillance activities are being carried out. For this reason, the Provincial Plant Protection Service and the E. Mach carry out annual inspections in various contexts, such as nurseries, urban greenery, natural and agricultural areas, and sites at risk. The investigations are based on visual inspections of the plants and, if necessary, on sampling and laboratory analyses.
Asian long-horned beetles can be eradicated, provided that the affected plants are quickly identified and eliminated. Therefore, the monitoring of potential host species and, in the event of infestation, the cutting down of plants with subsequent chipping of all resulting material is essential. In view of their dangerousness, if adults or plants with symptoms of attack are found, it is essential to intervene promptly to prevent their spread across the territory.
In order to effectively protect the territory, however, the cooperation of every professional, but also of every individual citizen, is indispensable.
SIGNS. Since Asian long-hornworms are considered a serious danger both for urban greenery and for natural and fruit-growing areas, the presence (even doubtful) of adults or symptomatic plants must be reported immediately to the Provincial Phytosanitary Service (tel. 0461-495660; e-mail serv.agricoltura@provincia.tn.it; pec serv.agricoltura@pec.provincia.tn.it)
REFERENCE REGULATIONS: Regulation (EU) 2016/ 2031; Implementing Regulation (EU) 2019/2072; Commission Implementing Regulation (EU) 2022/2095 of 28 October 2022; Legislative Decree no. 19/2021.