Experimental Nets for a Protection System against the Vectors of Xylella fastidiosa Wells et al.

Sergio Castellano,Giacomo Scarascia-Mugnozza,Antonella Di Palma,Giuseppe Starace,Marco Lippolis,Giacinto Germinara

doi:10.3390/agriculture9020032

Abstract

The effectiveness of experimental nets in preventing the access of adult meadow spittlebug Philaenus spumarius L., the main vector of Xylella fastidiosa Wells et al. subspecies pauca, sequence type (ST) 53, in olive tree nurseries and orchards was evaluated. To optimize the net design, mesh size, kind of fabric, thread typology, and radiometric properties, six nets with different mesh sizes and kinds of fabric were evaluated in laboratory and in field experiments. Laboratory bioassays evaluating the capability of adult spittlebugs to pass through nets with different mesh sizes (1.2, 1.8, 2.4 mm) showed that all nets with a mesh size equal to or lower than 2.4 mm prevented insect crossing. These results were confirmed in field conditions using an experimental net box apparatus. Further laboratory tests showed a positive correlation between porosity and radiometric properties of the nets. Three prototypes of thermally stabilized flat woven nets made of circular cross-sectional yarns, knitted net with strips, and knitted nets made of yarns were tested after the evaluation of their potential usability in terms of porosity stability. The knitted net features were found to be the most suitable. The net transmissivity of the total and direct component of solar radiation in the photosynthetically active radiation and the infrared ranges increased with the net porosity. A prism-shaped wooden frame with a triangular base covered with the knitted net with a 2.4 mm mesh confirmed the insect’s capability of reaching considerable heights, up to 2.85 m. Hence, based on our results, the monowire knitted net with a 2.4 mm mesh can be used in open field nursery and olive orchards to prevent the access of P. spumarius adults and to shield the openings of greenhouse nurseries.

Highlights

In the Apulia region, olive tree cultivation covers almost 370,000 ha, with a yearly economic value of production around 492 M€ [1], representing 53.3% of the overall farmland in the southern area of the region [2]
Six nets were tested: F-d1 flat woven with mesh size 1.2 mm, F-d2 flat woven with mesh size 1.8 mm, F-d3 flat woven with mesh size 2.4 mm, KS-d1 knitted net made of strips and wires with mesh size 1.2 mm, KS-d2 knitted net made of strips and wires with mesh size 1.8 mm, and KW-d3 knitted net only made of wires with mesh size 2.4 mm
A net with mesh size equal to or lower than 2.4 mm can successfully prevent the arrival of meadow spittlebugs on plants and, the possible transmission of X. fastidiosa

Summary

Introduction

In the Apulia region, olive tree cultivation covers almost 370,000 ha, with a yearly economic value of production around 492 M€ [1], representing 53.3% of the overall farmland in the southern area of the region [2]. In 2010, olive trees on the west coast of Salento Peninsula (Apulia region, Italy) began to decline and die with a condition of unknown aetiology called “olive quick decline syndrome” [4]. Saponari et al [5] demonstrated that olive trees with leaf scorch symptoms Quarantine was not able to limit the diffusion of the bacterium and, by the end of 2013, the affected area had grown to almost the entire Salento Peninsula.

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