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.

The leafhopper Scaphoideus titanus is the vector of ‘Candidatus Phytoplasma vitis’, the causal agent of Flavescence dorée (FD) a key disease for European viticulture. In organic vineyards, the control of S. titanus relies mostly on the use of pyrethrins that have suboptimal efficacy. During 2016, three field trials were conducted to evaluate the efficacy of kaolin, orange oil, insecticidal soap and spinosad against S. titanus nymphs, in comparison with pyrethrins. The activity of kaolin was evaluated also in the laboratory. In all field trials, kaolin had an efficacy against nymphs comparable to pyrethrins, while the other products were not effective. Laboratory results confirmed that kaolin increased nymph mortality. In organic vineyards, kaolin and pyrethrins are valuable tools in the management of FD. Nevertheless, their efficacy is lower compared to that of the synthetic insecticides used in conventional viticulture. Therefore, further research should be conducted in order to identify alternatives to synthetic insecticides for S. titanus control in the context of organic viticulture.

To reduce the impact of synthetic insecticides on human health and the environment, eco-friendly alternatives must be investigated. Knowledge of the side effects on pests and natural enemies of natural products applied to vineyards is very useful. Sulfur dust, which is used in vineyards to control powdery mildew, is investigated in laboratory and field bioassays for its effects on Lobesia botrana egg laying, egg hatching, and larval settlement. In field trials, the efficacy of sulfur dust against the two L. botrana carpophagous generations is compared with that of Bacillus thuringiensis and kaolin, and its side effects on the phytoseiid mite Kampimodromus aberrans are evaluated. In the bioassays, sulfur dust reduced female survival by 43%, egg laying by around 80%, egg hatching by 10%, and larval settlement by 55%. In field trials, sulfur dust caused a significant decrease in the number of L. botrana larval nests of both generations, even though the efficacy was lower than that of B. thuringiensis. No negative effects of sulfur dust on the predatory mite population density was observed. On the basis of these results, in the context of Integrated Pest Management strategies in vineyards, the activity of sulfur dust against L. botrana could be exploited by timing its application to the beginning of egg laying.

Hyalesthes obsoletus is the vector of “Candidatus Phytoplasma (Ca. P.) solani,” the causal agent of grapevine yellows Bois noir (BN). The relationships among the planthopper, its main herbaceous hosts as phytoplasma reservoirs (Convolvolus arvensis and Urtica dioica) and BN spreading were studied in northern Italy. In two areas the relationship between host plants and the phenology and survival of planthopper adults was investigated in potted plants and in field conditions. Moreover, H. obsoletus ecology, newly symptomatic grapevine occurrence and “Ca. P. solani” tuf-types’ presence were studied in two vineyards (2014–2019). An earlier occurrence of H. obsoletus adults on C. arvensis than U. dioica and better adult survival of the originating host were observed. When U. dioica was prevalent, the vector occurred almost exclusively along the ditch outside the vineyard. Hyalesthes obsoletus amount varied widely from year to year and nymphal mortality due to late frosts was supposed. In one vineyard, the amount of newly symptomatic grapevines was significantly correlated with vector abundance in the previous year. The “Ca. P. solani” tuf-type was influenced by vector population levels on the two hosts. Since the abundance of H. obsoletus populations on the two hosts influences BN epidemiology and dynamics and the “Ca. P. solani” tuf-type, this must be considered in BN control strategies.

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.

The hypothesis that bunch-zone leaf removal reduces infestations of the European grapevine moth, Lobesia botrana (Denis & Schiffermüller) (Lepidoptera: Tortricidae), by increasing egg and larval mortality owing to sunlight exposure was evaluated in the laboratory by subjecting different egg stages (white, red-eyes, and black-head) and newly hatched larvae to high temperatures. Based on temperatures recorded in a northern Italian vineyard on sun-exposed berries belonging to south-west facing bunches, eggs were subjected to constant temperatures of 40 °C and 37 °C for one or two periods of 3 or 6 h, and to 24-h temperature cycle with peak of 40 °C. Larvae were exposed to 24-h high-temperature cycles with peaks of 35, 37, and 40 °C. The results showed partial egg mortality at 40 °C, increasing with exposure hours and periods, and as eggs matured. Egg mortality was not affected by exposure to 37 °C. Larval survival already decreased significantly at 37 °C and was even lower at 40 °C. These laboratory data are in agreement with the hypothesis that temperatures reached by berries exposed to sunlight cause egg and larval mortality. Data on egg and larval susceptibility to high temperatures have also implications for species distribution and effects of climate change.