A molecular characterization of the invasive fig weevil Aclees taiwanensis in Italy

An economically important pest of Ficus carica L. is causing severe infestations in many fig nurseries and orchards in Italy. Belonging to the genus Aclees spp. (Coleoptera Curculionidae), this Asiatic species was accidentally introduced in Europe about 15 years ago, in a Tuscan nursery. Originally identified as Aclees cribratus Gyllenhal, it has been then reported as Aclees sp.cf. foveatus Voss and, more recently, identified as Aclees taiwanensis Kono. A serious damage to fig plants is caused mainly by the larvae, which drill tunnels into the wood and by adults that feed on buds, leaves and young fruits. The present survey applies molecular genetics techniques to reconstruct the genetic profile of the species. To this purpose, the partial sequence of the 18S rRNA gene and the hypervariable region ITS2 of the ribosomal cistron were used as molecular markers for specimens of A. taiwanensis collected in Italy and Aclees hirayamai Kono from Philippines. The analysis of the partial sequences of the 18S rRNA allowed the distinction of two haplotypes for each insect, except for a sample from Philippines, for which one haplotype does exist. The use of the ITS2 hypervariable region highlighted the existence of only one haplotype in the Italian accessions. Only in the sample collected in Lucca (2LU) two haplotypes were highlighted in ITS2. These results are discussed with the occurrence of A. taiwanensis in Italy.