USE OF NATURAL PRODUCTS AND CULTURAL PRACTICES IN THE SUSTAINABLE MANAGEMENT OF GRAPEVINE PESTS

Chapter 1. The use of synthetic insecticides for pest management can affect health and environment. In integrated pest management (IPM) their substitution with natural substances and the adoption of alternatives to chemical control is desirable. In this PhD dissertation, we considered the effect of natural compounds and cultural practices on some grapevine pests and their side effects on natural enemies. Chapter 2. The influence of kaolin and bunch-zone leaf removal (LR) on the grapevine leafhoppers, Empoasca vitis (Göthe) and Zygina rhamni Ferrari, and their egg parasitoids (Anagrus spp.) was tested in vineyards. The mode of action of kaolin on E. vitis nymphs was also studied in the lab. Kaolin applications reduced the populations of E. vitis and Z. rhamni nymphs and E. vitis leaf symptoms without impact on Anagrus spp. LR did not affect leafhopper populations. Feeding inhibition was the main mode of action of kaolin. Chapter 3. Field trials were conducted to evaluate the efficacy of some natural products in comparison with natural pyrethrins against the grapevine leafhopper Scaphoideus titanus Ball. Kaolin was evaluated against S. titanus nymphs also in the lab. In all field trials, kaolin had an efficacy against S. titanus nymphs comparable to or greater than natural pyrethrins while the other products were not effective. Lab results confirmed that kaolin increases nymph mortality. Chapter 4. The activity of kaolin on the European grapevine moth Lobesia botrana (Den. & Schiff.) was investigated in lab and field bioassays. In vineyards the efficacy of kaolin and Bacillus thuringiensis Berliner (BT), in combination or not with LR was assessed. In the lab, kaolin reduced female egg laying, fecundity and survival, hatching rate of eggs and larval settlement. In field bioassay, kaolin reduced female egg laying. In the field trials, kaolin, BT and LR reduced significantly L. botrana infestation. When the products were combined with LR, their efficacy increased and kaolin was not significantly different from BT. Chapter 5. The activity of sulfur dust (SD) on L. botrana was investigated in the lab and two trials were carried out in vineyards to compare the efficacy of SD with that of kaolin and BT. In the first trial, each treatment was in combination or not with LR. In the lab bioassays SD reduced both egg laying and larval settlement. In both trials, SD caused a significant decrease in the number of L. botrana larval nests and of damaged berries with an efficacy not different from both BT and kaolin. LR did not significantly reduce L. botrana infestation. Chapter 6. The efficacy of kaolin and citrus essential oil (CEO) was evaluated against mealybugs. Lab experiments and field trials were conducted in New Zealand on Pseudococcus calceolariae (Maskell) and Pseudococcus longispinus (Targioni Tozzetti), and in Italy on Planococcus ficus (Signoret). Kaolin was ineffective at controlling mealybugs in vineyards. In contrast, CEO increased mealybug mortality in the lab and reduced infestation in vineyards. Chapter 7. The effect of kaolin and LR on the phytoseiid predators Kampimodromus aberrans (Oudemans) and Typhlodromus pyri Scheuten was assessed in vineyards. In the lab, kaolin impact on adult females was also studied. In the field, kaolin and LR reduced K. aberrans and T. pyri populations which however recovered during the winter and next spring. In the lab, kaolin reduced female fecundity but not survival. Chapter 8. The impact of kaolin and LR on spiders and on some generalist predatory insects was assessed in vineyards. Kaolin and LR did not affect species richness and functional diversity. Kaolin reduced the abundance of the hunter spiders Oxypidae and Salticidae, the web-builder spiders Araneidae and the predatory insects Orius sp., but increased the abundance of Coccinellidae Scymninae. LR increased the number of Aeolothrips sp. These effects were not consistent in all trials.