Relative Infestation Level and Sensitivity of Grapevine Cultivars to the Leafhopper Empoasca vitis (Hemiptera: Cicadellidae)

Insights into the Diversity and Population Structure of Predominant Typhlocybinae Species Existing in Vineyards in Greece

Insects of the subfamily Typhlocybinae (Hemiptera: Cicadellidae) are pests of economically important agricultural and horticultural crops. They damage the plants directly or indirectly by transmitting plant pathogens, resulting in significant yield loss. Several leafhoppers of this subfamily use vines as hosts. Accurate and rapid identification is the key to their successful management. The aim of this study is to determine the Typhlocybinae species that exist in vineyards all over Greece and investigate the relationship between them. For this purpose, yellow sticky traps were placed, morphological and molecular data were collected, and phylogenetic models were analyzed. The mitochondrial marker Cytochrome Oxidase Subunit I (mtCOI) was applied for the DNA and phylogenetic analysis. The combination of morphological and molecular data resulted in identifying the existence of six different species all over Greece: Arboridia adanae, Asymmetrasca decedens, Hebata decipiens, Hebata vitis, Jacobiasca lybica and Zygina rhamni. Forty-eight different haplotypes were found to exist in the different regions of the country.

Effect of Leaf Removal and Insecticide Applications on Population Densities of Leafhoppers and Mites Associated with Grapevines

In this study, we tested the effects of mechanical leaf removal, insecticide application, and their interaction on leafhoppers and phytophagous and predatory mites occurring in two vineyards over three growing seasons. Leaf removal was performed in the fruit zone using a two-head pulsed air leaf remover, while insecticides were applied with a tunnel air-assisted sprayer at the maximum dose/ha recommended on the product label. Results demonstrated the efficacy of insecticide application in reducing the population densities of leafhoppers but also their detrimental effects on predatory mites. In a number of case studies, leaf removal reduced leafhopper and predatory mite densities. In one vineyard, phytophagous mite populations increased some weeks after leaf removal and insecticide application, highlighting the need to carefully consider the potential impact of vineyard management practices on non-target arthropods in the IPM framework.

Cicadomorpha Community (Hemiptera: Auchenorrhyncha) in Portuguese Vineyards with Notes of Potential Vectors of Xylella fastidiosa

Cicadomorpha (Hemiptera) insects are currently responsible for a growing negative impact on the agricultural economy due to their ability to directly damage crops or through the capacity to act as vectors for plant pathogens. The phytopathogenic bacterium Xylella fastidiosa, the causal agent of Pierce's disease in vineyards, is exclusively transmitted by insects of this infraorder. Therefore, knowledge of the Cicadomorpha species and understanding their biology and ecology is crucial. In this work, in 2018 and 2019, the canopy and inter-row vegetation of 35 vineyards distributed in mainland Portugal were sampled to investigate species composition, richness, and diversity of the Cicadomorpha community, with a special focus given to vectors and potential vectors of X. fastidiosa. A total of 11,834 individuals were collected, 3003 in 2018 and 8831 in 2019. Of the 81 species/morphospecies identified, only five are considered vectors or potential vectors of this pathogen, namely, Cicadella viridis (Linnaeus, 1758), Philaenus spumarius (Linnaeus, 1758), Neophilaenus campestris (Fallén, 1805), Lepyronia coleoptrata (Linnaeus, 1758), and N. lineatus (Linnaeus, 1758). Cicadella viridis was the most abundant xylem sap feeder, followed by P. spumarius. In addition, Cicadomorpha that cause direct damage to vines and vectors of grapevine yellows' phytoplasmas were also collected and identified in the sampled vineyards. The results suggested that vectors and potential vectors of X. fastidiosa and a large proportion of the population of Cicadomorpha have a positive correction with inter-row vegetation.

Occurrence, Density, and Transcriptomic Response of the Leafhopper Erythroneura sudra (Hemiptera: Cicadellidae) When Confronted With Different Fruit Tree Species

The leafhopper, Erythroneura sudra (Distant) is becoming a dominant insect pest, and usually can cause significant damage to fruit production in northern China. We studied the occurrence and density of E. sudra on three fruit tree species and its transcriptomic responses when it was fed on leaves of these tree species. A higher density and survival rate of E. sudra were recorded when it fed on leaves of peach (Amygdalus persica L.) (Rosales: Rosaceae) and cherry (Cerasus pseudocerasus Lindl) (Rosales: Rosaceae) than on apple (Malus domestica Mill) (Rosales: Rosaceae). Also, feeding on M. domestica induced the largest variation in transcriptomic profiles in E. sudra. In total, 166 genes were differentially expressed (89 upregulated and 77 downregulated) in E. sudra when it fed on M. domestica, compared to when it fed on the other two tree species. The upregulated genes were mainly related to 'response to oxidative stress', 'stress-resistance', and 'xenobiotic metabolic process'. The downregulated genes were mainly related to 'structural constituent of cuticle', 'biosynthetic process', and 'development regulation'. These results suggested that M. domestica significantly changed the expression of many genes and consequently caused lower occurrence and density of E. sudra. Such information could enhance our understanding of the leafhopper-host plant relationship. Additionally, it can contribute to the improvement of current control strategies for this pest.

An update of the Worldwide Integrated Assessment (WIA) on systemic insecticides. Part 3: alternatives to systemic insecticides

Over-reliance on pesticides for pest control is inflicting serious damage to the environmental services that underpin agricultural productivity. The widespread use of systemic insecticides, neonicotinoids, and the phenylpyrazole fipronil in particular is assessed here in terms of their actual use in pest management, effects on crop yields, and the development of pest resistance to these compounds in many crops after two decades of usage. Resistance can only be overcome in the longterm by implementing methods that are not exclusively based on synthetic pesticides. A diverse range of pest management tactics is already available, all of which can achieve efficient pest control below the economic injury level while maintaining the productivity of the crops. A novel insurance method against crop failure is shown here as an example of alternative methods that can protect farmer's crops and their livelihoods without having to use insecticides. Finally, some concluding remarks about the need for a new framework for a truly sustainable agriculture that relies mainly on natural ecosystem services instead of chemicals are included; this reinforcing the previous WIA conclusions (van der Sluijs et al. Environ Sci Pollut Res 22:148-154, 2015).

Preferences and Performance of Erythroneura sudra (Homoptera: Cicadellidae) on Five Fruit Tree Species (Rosaceae)

Erythroneura sudra is a leafhopper occurring in northern China, which causes significant damage to fruit. The relationships between E. sudra and five fruit tree species (Rosaceae) were studied for 3 yr. The highest relative density of E. sudra was recorded on leaves of Amygdalus persica L. and Cerasus pseudocerasus Lindl. Likewise, it had the highest survival rate and shortest developmental time when it fed on these two plants species, indicating that they were the most preferred by E. sudra than the other plant species. The relative density and growth performance of E. sudra were negatively correlated with the levels of tannins and flavonoids in the leaves of the host species. Both plant species had relatively lower flavonoids and tannins, and this may have contributed to the enhanced survival and population growth of E. sudra. These results can guide the development of improved management strategies for this pest.

Texture features explain the susceptibility of grapevine cultivars to Drosophila suzukii (Diptera: Drosophilidae) infestation in ripening and drying grapes

Grapevine is a well-known host plant of the invasive pest Drosophila suzukii, but its susceptibility to pest oviposition and development greatly depends on the cultivar. To address environmental sustainability during viticultural zoning planning, new vineyard plantation and Integrated Pest Management programmes, it is essential to take pest pressure and cultivar susceptibility into account. To determine the different grapevine cultivars susceptibility to D. suzukii, we tested twelve widely spread cultivars during the ripening period. We also tested three cultivars during the drying period for raisin wine production. The infestation and emergence rates were consequently related to chemical and texture features of the berries to explain the role of skin and pulp characteristics in determining the nature of the susceptibility. Our results showed that susceptibility to D. suzukii infestation varies across cultivars. On ripening grapes, infestation is primarily influenced by skin and pulp firmness, elasticity and consistency. Suitability for egg development resulted mainly related to skin and pulp deformation. In a drying loft, infestation may also occur in relation to skin and pulp consistency. Lastly, we discuss the practical implication of the underestimated role of berry texture in D. suzukii oviposition and emergence success, in both ripening and drying grapes.

Influence of Grapevine Cultivar on the Second Generations of Lobesia botrana and Eupoecilia ambiguella

Grapevine cultivar can affect susceptibility to Lobesia botrana and Eupoecilia ambiguella with important implications on control strategies. A four-year study was carried out in north-eastern Italy on 10 cultivars (Cabernet Sauvignon, Carménère, Chardonnay, Merlot, Refosco dal Peduncolo Rosso, Rhine Riesling, Sauvignon Blanc, Terrano, Tocai Friulano and Verduzzo Friulano) grown in the same vineyard to assess whether the cultivar affects second-generation population levels of the two vine moths and L. botrana larval age composition. The influence of bunch traits measured at the peak of egg hatching on demographic parameters was also evaluated. Over the four years, L. botrana significantly prevailed over E. ambiguella in nine cultivars. Chardonnay and Tocai Friulano were the most infested cultivars and Merlot was the least infested. At the sampling date, the age composition of L. botrana varied with cultivar, with the larvae being significantly older on Chardonnay and younger on Carménère, Merlot and Verduzzo Friulano. Older larval age was significantly associated with higher bunch compactness. Larval infestation was not significantly influenced by either bunch compactness or berry volume, which suggested a more important role for contact and volatile substances mostly originating from the berries. These results allow for the improvement of Integrated Pest Management strategy against vine moths.

Efficacy and Mode of Action of Kaolin in the Control of Empoasca vitis and Zygina rhamni (Hemiptera: Cicadellidae) in Vineyards

During 2015, the influence of kaolin applications and bunch-zone leaf removal on the grapevine leafhoppers, Empoasca vitis (Göthe) and Zygina rhamni Ferrari, and their egg parasitoids (Anagrus spp.) was tested in four vineyards of northeastern Italy. The mode of action of kaolin on E. vitis nymphs was also investigated in the laboratory. In the treated plots, kaolin was applied at a rate of 2% w/v on two occasions separated by 5-6 d. In two vineyards, it was applied either on the whole canopy or the bunch zone at the beginning of the E. vitis second generation (preventive criterion), and in the other two vineyards, it was applied to the whole canopy at the peak of the E. vitis third generation (curative criterion). Both the preventive and curative kaolin applications caused a significant decrease in the populations of E. vitis and Z. rhamni nymphs. The effect of the preventive applications was persistent and was associated with reduced E. vitis leaf symptoms. Kaolin did not influence the activity of Anagrus spp. Bunch-zone leaf removal did not affect leafhopper populations. Laboratory experiments showed that inhibition of feeding was the main mode of action through which kaolin affected nymph populations. Based on these outcomes, kaolin could be a valuable alternative to synthetic insecticides in controlling grapevine leafhoppers.