Aclees taiwanensis: a new pest of Ficus carica in Southern Europe
Aclees taiwanensis (Coleoptera: Curculionidae), native to Asia, is a pest of Ficus species. In Europe, it was first found in 1997 in France and in 2005 in Italy attacking fig trees (Ficus carica). However, due to difficulties in the insect identification, it was initially recorded under other names (Aclees cribratus, Aclees sp. cf. foveatus). Damage is caused by larvae which bore galleries within the trunk and surface roots, causing disruption in the sap flow, wilting, and tree mortality. Adult weevils feed on unripe fruit, leaves and buds of young plants without causing severe damage.
Using several citizen-science platforms and insect forums, it could be established that records of A. taiwanensis have been made in 7 Italian regions (Lazio, Toscana, Liguria, Lombardia, Veneto, Marche, and Umbria) and 1 French region (Provence-Alpes-Côte d’Azur). The highest numbers of observations were made in Lazio, Toscana and Liguria.
Field studies were also carried out in Italy on the biology and host range of A. taiwanensis. In these experiments made on seedlings, all studied Ficus species (F. pandurata, F. carica, F. benjamina, F. macrocarpa) were susceptible to A. taiwanensis. Field observations showed that A. taiwanensis was detectable all-year round, although during winter adult weevils moved to soil or bark crevices. Trapping data showed that the species seem to have two major peaks of population density, in June-July and September-October.
The authors consider that A. taiwanensis is an invasive species that is currently spreading in Southern Europe. As A. taiwanensis is a threat to F. carica, and potentially other Ficus species cultivated for ornamental purposes, efficient control strategies should be developed against it.
Sources
Farina P, Mazza G, Benvenuti C, Cutino I, Giannotti P, Conti B, Bedini S, Gargani E (2021) Biological notes and distribution in Southern Europe of Aclees taiwanensis Kôno, 1933 (Coleoptera: Curculionidae): a new pest of the fig tree. Insects 12, 5. https://dx.doi.org/10.3390/insects12010005