Physical and Chemical Traits of Grape Varieties Influence Drosophila suzukii Preferences and Performance

Abstract

The cuticle-covered surface forms the interface between plant parts, including fruits, and their environment. The physical and chemical properties of fruit surfaces profoundly influence plant-frugivore interactions by shaping the susceptibility and suitability of the host for the attacker. Grapevine (Vitis vinifera, Vitaceae) serves as one of the various host plants of the spotted wing drosophila, Drosophila suzukii Matsumura (Diptera: Drosophilidae), which is invasive in several parts of the world and can cause major crop losses. The susceptibility of wine towards this pest species differs widely among varieties. The objective of our study was to identify physical and chemical traits of the berry surface that may explain the differences in susceptibility of five grape varieties to D. suzukii. Both preferences of adult D. suzukii and offspring performance on intact versus dewaxed (epicuticular wax layer mechanically removed) grape berries were investigated in dual-choice assays. Moreover, the morphology and chemical composition of cuticular waxes and cutin of the different varieties were analyzed. Bioassays revealed that the epicuticular wax layer of most tested grape varieties influenced the preference behavior of adult flies; even less susceptible varieties became more susceptible after removal of these waxes. In contrast, neither offspring performance nor berry skin firmness were affected by the epicuticular wax layer. The wax morphology and the composition of both epi- and intracuticular waxes differed pronouncedly, especially between more and less susceptible varieties, while cutin was dominated by ω-OH-9/10-epoxy-C18 acid and the amount was comparable among varieties within sampling time. Our results highlight the underestimated role of the epicuticular surface and cuticle integrity in grape susceptibility to D. suzukii.

Towards Sensor-Based Phenotyping of Physical Barriers of Grapes to Improve Resilience to Botrytis Bunch Rot

“…Furthermore, its biomechanical properties are important to prevent fruit cracking under conditions of high humidity, which represents one important starting point for fungal growth (Khanal and Knoche, 2017;Petit et al, 2017;Lara et al, 2019). In contrast to observations that cuticle thickness does not correlate with water permeability (Riederer and Schreiber, 2001), it was shown to be a relevant factor for determining resistance to fungal infections in apple, cranberry (Vaccinium oxycoccos L.), stone fruit, and table grapes (reviewed by Lara et al, 2019), and that it influences the susceptibility of grapevines to Drosophila suzukii (Weißinger et al, 2021). Furthermore, intraand epicuticular waxes are extraordinary important, because they fulfill different functions as barriers for water movement (cuticle permeability), resulting in reduced water loss from tissues, and reduced water absorption from the environment, light reflection, and drying of surface (Lara et al, 2019).…”