Ficus carica L. is one of the earliest cultivated fruit trees, and figs are a typical fruit of the Mediterranean diet and traditional medicine as well. In recent years, a new pest, the black weevil Aclees taiwanensis Kȏno, 1933 (Coleoptera: Curculionidae) native to Asia, has been recorded in France and Italy. Aclees taiwanensis causes the rapid death of the fig tree by its larvae that dig alimentation galleries in the trunk and surface roots, compromising the phloem flux. In Italy, from 2005, the year of the first detection of A. taiwanensis, the fig production has nearly halved, decreasing from 20.09 t to 10.65 t. To date, no specific EU regulation has been applied to prevent the A. taiwanensis spread, and we can reasonably expect a rapid diffusion of this pest all over the Mediterranean area. To avoid the loss of the Mediterranean fig orchards, effective strategies to detect and control the black weevil are required. Such strategies need a detailed knowledge of A. taiwanensis distribution, biology, and physiology. This paper updates the known distribution of this species in Southern Europe, using a citizen science approach, and describes, under laboratory and field conditions, its main biological traits.
In Europe, the recently reported plant pathogen Xylella fastidiosa subsp. multiplex affects several wild, ornamental, and cultivated trees causing scorch diseases. In 2018, the sequence type 87 was reported in Tuscany on Mediterranean shrubs and trees. Although spittlebugs (Hemiptera: Aphrophoridae) were already identified as main vectors of this bacterium in Europe, their role in the transmission of this subspecies has not been ascertained yet. In this study the ability of Philaenus spumarius and Neophilaenus campestris to acquire and transmit Xylella fastidiosa subsp. multiplex sequence type 87 from and to Rhamnus alaternus was evaluated in two-year semi-field experiments. To acquire the bacterium, insects were confined on wild, naturally infected R. alaternus shrubs for 120 h. Then, they were transferred to healthy plants and maintained in cages for 96 h. To follow the infection, plant samples were collected every two months for three times. Tested plants were destroyed at the end of experiments and roots, twigs and leaves were analysed. Philaenus spumarius showed a significantly higher survival rate than N. campestris. The infection status of both insects and plants was assessed through molecular analysis. P. spumarius and N. campestris were able to infect healthy plants although the acquisition rate and the estimated probability of transmission appeared to be low. These findings provide new accounts on the role of two polyphagous insect vectors in spreading a quarantine organism, which is lethal to a huge number of plant species. However, further studies are needed to disclose more specific interactions within this complex pathosystem.
The black weevil Aclees taiwanensis Kôno, 1933 (Coleoptera: Curculionidae) is a xylophagous insect native to Southeast Asia and introduced to Italy in 2005. Here, the species completes its entire life cycle on Ficus carica L., causing economic damage and leading to the plants’ death. Nowadays, there are no insecticides registered for its control. In this study, a commercial product based on Beauveria bassiana, Naturalis®, was associated with Rincotrap® tissue. Semi-field trials were carried out on fig seedlings by comparing two different concentrations (3% and 10%) of this entomopathogenic fungus distributed in suspension on Rincotrap® bands. The results showed that the fungal product had a biocidal effect in both treatments. Afterward, trials were conducted in a fig orchard in order to verify the effectiveness of this association in the field. The addition of Naturalis® at a 3% concentration to Rincotrap® bands did not alter the number of adults captured. The total mortality was 43.7% and 23.8%, respectively, in the treated and control plots. Among the total number of dead adults, only the mortality rates of B. bassiana exceeded 70% in both plots. Further long-term studies in several environments are necessary to improve this technique and create an integrated control system for the black fig weevil.
In recent years, the spread of the phytopathogenic bacterium Xylella fastidiosa Wells et al., 1987 (Bacteria: Proteobacteria, Gammaproteobacteria) has posed a significant threat to olive cultivation in Italy, particularly in regions of high economic and agronomic value such as Apulia (Southern Italy). In this two-year study (2019–2020), we investigated the Auchenorrhyncha community in three representative olive farms in Tuscany (Central Italy), another region with highly valuable olive-growing, comparing traditional (400 trees/ha) and super-high-density (1500 trees/ha) management systems. Adult insects were collected monthly from May to November using sweep net sampling on both olive tree canopies and herbaceous ground cover. In total, 1844 individuals belonging to 25 genera and five families were identified. Philaenus spumarius L. and Neophilaenus campestris (Fallén) (Cercopoidea: Aphrophoridae) were confirmed as the most prevalent X. fastidiosa vectors in each site. However, data analysis revealed that Auchenorrhyncha community composition was significantly influenced by site and vegetation stratum, but not by olive grove management systems. These findings contribute to a deeper understanding of the composition of Auchenorrhyncha communities associated with olive groves, highlighting that new super-high-density management does not influence the presence and abundance of X. fastidiosa vectors.