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

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.

Side Effects of Kaolin and Bunch-Zone Leaf Removal on Generalist Predators in Vineyards

In vineyards, kaolin application and bunch-zone leaf removal (LR) were effective in the control of leafhoppers and Lobesia botrana, but their side effects on generalist predators are still poorly understood. In north-eastern Italian vineyards, the impact of kaolin and LR on species and functional diversity of spiders, as well as the abundance of spiders and generalist predatory insects, was assessed in one vineyard for two consecutive years and in two vineyards for one year. The ecological indices of the spider community were never influenced by kaolin and only in one case were they influenced by LR. At the spider family level, kaolin reduced the abundance of Araneidae, Oxypidae and Salticidae, but only in single cases. In single cases, kaolin reduced the amount of Orius sp. anthocorids and increased that of Scymninae coccinellids, whereas LR increased the amount of Aeolothrips sp. The moderate use of kaolin and the application of LR had negligible and inconsistent impacts on generalist predatory arthropods in vineyards and were therefore, compatible with IPM strategies.

Frequency of processed kaolin application to prevent Diaphorina citri infestation and dispersal in flushing citrus orchards

BACKGROUND

Processed kaolin is a promising tactic that can be utilized for managing Diaphorina citri Kuwayama infestation. However, the frequency of kaolin application to protect citrus trees during flushing remains undetermined. The objective of this study was to ascertain the frequency of kaolin application (2%) required to reduce D. citri infestation and dispersal in flushing citrus orchards and to measure the spectral reflectance of kaolin-sprayed leaves.

RESULTS

Trees sprayed with kaolin at 7- and 14-day intervals showed an 80% psyllid reduction compared to untreated trees. In addition, there was lower psyllid dispersal in the kaolin-sprayed plots. Spectral measurements (wavelengths between 320 and 700 nm) showed an increased reflectance of 35.4% (adaxial leaf side) and 21.9% (abaxial leaf side) in mature leaves, and 9% (adaxial leaf side) and 2.2% (abaxial leaf side) in kaolin-sprayed immature leaves compared to untreated trees.

CONCLUSION

Application of kaolin (2%) at 7- and 14-day intervals can be an important and sustainable tool for reducing D. citri infestation and dispersal in flushing citrus orchards. The reduced D. citri population in plots with both kaolin application intervals may be related to the visual effect (whitish aspect) and increased light reflectance in citrus trees, which are probably the main mechanisms by which kaolin interferes on D. citri host finding behavior. © 2021 Society of Chemical Industry.

Reduction in Insect Attachment Caused by Different Nanomaterials Used as Particle Films (Kaolin, Zeolite, Calcium Carbonate)

In the present investigation, we compared the reduction in attachment ability of the southern green stinkbug Nezara viridula (Hemiptera: Pentatomidae) to glass induced by three different nanoparticle (kaolin, zeolite, and calcium carbonate) films. Using traction force experiments, behavioral experiments, and scanning electron microscopy observations, we analyzed the insect attachment ability and linear speed on untreated and treated glass with the three particle films. The three nanomaterials strongly reduced insect attachment ability mainly owing to contamination of attachment pads. The ability to reduce insect attachment was different for the three tested particle films: kaolin and zeolite induced a significantly higher reduction in N. viridula safety factor than calcium carbonate. The coating of the surface was more uniform and compact in kaolin and zeolite compared to calcium carbonate particle film. Moreover, kaolin and zeolite particles can more readily adhere to N. viridula attachment devices, whereas calcium carbonate particles appeared less adherent to the cuticular surface compared to the two aluminosilicate (kaolin and zeolite) particles. Only the application of kaolin reduced insect linear speed during locomotion. Nanoparticle films have a great potential to reduce insect attachment ability and represent a good alternative to the use of insecticides for the control of pentatomid bugs and other pest insects.

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).

The Control of the American Leafhopper Erasmoneura vulnerata (Fitch) in European Vineyards: Impact of Synthetic and Natural Insecticides

The American leafhopper Erasmoneura vulnerata, detected in Europe in the early 2000s, has recently become a pest in North-Italian vineyards. Infestations were recorded in organic and conventional vineyards despite the application of insecticides targeting other pests. Erasmoneura vulnerata completes three generations per year, and the second generation is frequently associated with large populations. The selection of appropriate active ingredients and the timing of their application is crucial for effective pest control. Field trials were carried out in Northeastern Italy, using a randomized design, to evaluate the impact of insecticides applied against other grapevine leafhoppers on E. vulnerata populations. The beginning of the second generation was selected as the best time for insecticide application. For natural products, two applications were planned. Among the selected insecticides, the most effective were acetamiprid, flupyradifurone and lambda-cyhalothrin. Regarding natural products, the most effective was kaolin which could represent an alternative to pyrethrins in organic vineyards. The identification of pest threshold levels and the evaluation of side effects of the most effective insecticides on key natural enemies occurring in vineyards are required.

Side Effects of Sulfur Dust on the European Grapevine Moth Lobesia botrana and the Predatory Mite Kampimodromus aberrans in Vineyards

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.

Colonization Patterns, Phenology and Seasonal Abundance of the Nearctic Leafhopper Erasmoneura vulnerata (Fitch), a New Pest in European Vineyards

Simple Summary

The leafhopper Erasmoneura vulnerata (Fitch) (Hemiptera: Cicadellidae) is native to North America, and was found in Europe for the first time (north-eastern Italy) in 2004 where it remained a minor pest of grapevine for more than ten years. Recently, its importance increased in commercial vineyards located in north-eastern Italy, where outbreaks of E. vulnerata populations with severe leaf symptoms were observed despite insecticide applications. Information on its biology and ecology is needed for the development of management strategies. Here, we investigated the phenology and seasonal abundance of E. vulnerata in commercial vineyards. We found that E. vulnerata can complete three generations per growing season. Vineyard colonization by overwintered adults showed a clear edge effect, suggesting an effect of overwintering sites (e.g., rural buildings and hedgerows) adjacent to vineyards. The impact of natural enemies on pest populations appeared to be limited and mostly related to egg parasitoids. Organic vineyards were more heavily infested by E. vulnerata compared to conventional vineyards, likely due to the low effectiveness of natural insecticides typically used in the former farms. The results generated by this study provide implications for the management of this pest in European vineyards.

Abstract

The Nearctic leafhopper Erasmoneura vulnerata (Fitch), detected in Europe for the first time (north-eastern Italy) in 2004, has remained a minor pest of grapevine for more than 10 years. The first outbreaks of E. vulnerata were reported in 2016 in commercial vineyards located in north-eastern Italy. High population densities and severe leaf symptoms (i.e., leaf discoloration and fall) were observed in late summer despite the application of insecticides. Investigations were carried out from 2017 to 2019 in 10 vineyards located in Veneto region (Vicenza and Verona provinces) to shed light on the seasonal abundance of E. vulnerata on different Vitis vinifera cultivars. Pest phenology was studied in six vineyards where the impact of insecticides was minimal. Erasmoneura vulnerata completed three generations in each of the growing seasons. Vineyard colonization by overwintered adults showed a clear edge effect, suggesting the influence of overwintering sites (e.g., rural buildings and hedgerows) in vineyard margins. The impact of natural enemies on pest populations appeared to be limited and mostly related to egg parasitoids. Organic vineyards were more heavily infested by E. vulnerata compared to conventional vineyards, likely due to the minimal efficacy of natural insecticides typically used in the former farms.

The functional agrobiodiversity in the Douro demarcated region viticulture: utopia or reality? Arthropods as a case-study – A review

Aiming to reduce the losses of biodiversity and the degradation of associated ecosystem services, the United Nations established the 2011-2020 period as the UN Decade on Biodiversity. During this period, the countries involved compromised on implementing the Strategic Plan for Biodiversity, including the Aichi Biodiversity Targets. The argument is that biological diversity underpins the functioning of ecosystems and the provision of services essential to human well-being, further contributing to economic development and the achievement of the Millennium Development Goals. The purpose of this review is to present results of research and academic works carried out over several years in the Douro Demarcated Region in the field of functional agrobiodiversity, understood as the part of ecosystem biodiversity that provides ecosystem services, which support sustainable agricultural production and can also bring benefits to the regional and global environment and to society as a whole. Such studies specifically aimed to contribute knowledge about the diversity of arthropods in the vineyard ecosystem and about practices that can increase their abundance, diversity and services provided. In this context, a general characterization of the arthropod community identified in the vineyard ecosystem is conducted, complemented by information on the role played, by the taxonomic groups identified. The importance of increasing arthropod populations, the vegetation of vineyard slopes, and the existence of shrubs, forests and hedgerows next to the vineyards is discussed. The fundamental role of soil management practices is also referred, namely that of ground cover and the application of compost from winery wastes in the abundance and diversity of these organisms populations. Finally, bearing in mind the importance of the use of this information by vine growers, the measures taken for its dissemination are also presented.

Side Effects of Kaolin and Bunch-Zone Leaf Removal on Predatory Mite Populations (Acari: Phytoseiidae) Occurring in Vineyards

The effects of kaolin and bunch-zone leaf removal on populations of predatory mites Kampimodromus aberrans (Oudemans) and Typhlodromus pyri Scheuten were assessed in the context of four trials (2015-2016) carried out against Lobesia botrana (Denis and Schiffermüller) (Lepidoptera: Tortricidae) in vineyards located in north-eastern Italy. Laboratory experiments were performed to evaluate the effects of kaolin on the survival and fecundity of K. aberrans and T. pyri populations originating from the same grape-growing area. In field trials, kaolin caused a gradual decrease in population density levels of both phytoseiid species (with the maximum reduction ranging from 49 to 91%) with a complete population recovery in the next spring. In laboratory experiments, kaolin was moderately harmful to both species, reducing their fecundity significantly (around 60%). Bunch-zone leaf removal determined lower phytoseiid populations in all trials, but this effect was significant only for K. aberrans in one of them. A limited use of kaolin and the adoption of bunch-zone leaf removal did not irreversibly affect phytoseiid populations in vineyards and thus can be considered compatible with IPM strategies.

Vibrational mating disruption of Empoasca vitis by natural or artificial disturbance noises

BACKGROUND

The green leafhopper, Empoasca vitis, is a polyphagous pest of grapevine and tea plants. To date population density is controlled primarily by insecticides and there is a demand for more sustainable controls. To develop a vibrational mating disruption method, the natural occurrence of a 'disruptive signal' was investigated. Further, the efficacy of natural and artificial 'disruptive signals' was determined.

RESULTS

With behavioral trials we described male rivalry and recorded a species-specific disruptive signal (DP). The DP, a single pulse overlapping the competitor male call, interfered with the rival's ability to locate the female. Laboratory playback disruption trials revealed that the pair formation process was prevented by artificial disturbance noises that included the following features: E. vitis DP, Scaphoideus titanus disturbance noise, and a pure tone (250 Hz). Among these, the pure tone was most efficient at preventing mating.

CONCLUSION

Results support development of a vibrational mating disruption method as a control strategy for E. vitis. To simultaneously disrupt the mating of E. vitis and S. titanus, the possibility of applying the S. titanus disturbance noise combined with the pure tone is discussed. © 2018 Society of Chemical Industry.

Processed kaolin affects the probing and settling behavior of Diaphorina citri (Hemiptera: Lividae)

BACKGROUND

Alternative methods that have the potential to reduce the entry of Diaphorina citri Kuwayama (Hemiptera: Liviidae), the major citrus pest worldwide, into commercial groves could be a viable approach for huanglongbing management. Kaolin is an aluminum silicate that when sprayed on plants forms a white particle film that interferes with host recognition by the insects. Diaphorina citri orients towards the host plants by visual and olfactory cues. The purpose of the study was to determine the effect of processed kaolin on D. citri settling (no-choice) and probing behavior [electrical penetration graph (EPG) technique] under laboratory conditions, and to study its host plant finding ability and dispersal under field conditions in the absence and presence of young shoots.

RESULTS

Under laboratory conditions, kaolin caused an overall reduction of 40% in the number of psyllids settled on treated seedlings; furthermore, the proportion of individuals that were able to reach the phloem was 50% lower on kaolin-treated plants than on untreated plants. In the field, the plant finding ability of D. citri was disrupted on kaolin-treated trees (overall reduction of 96%), regardless of the vegetative condition, and psyllid dispersal was slower in kaolin-treated plots than in the untreated control.

CONCLUSION

This study clearly demonstrates that processed kaolin interferes negatively with different aspects of the host plant finding ability of D. citri. These findings suggest that processed kaolin has a high potential to reduce huanglongbing primary infection. © 2018 Society of Chemical Industry.

Control of Scaphoideus titanus with Natural Products in Organic Vineyards

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.