Soil and foliar application of rock dust as natural control agent for two-spotted spider mites on tomato plants

Abstract

Mineral-based products represent a valid alternative to synthetic pesticides in integrated pest management. We investigated the effects of a novel granite dust product as an agent for controlling two-spotted spider mites, Tetranychus urticae Koch (Acari: tetranychidae), on tomato plants (Solanum lycopersicum L.). two-choice tests for repellency and repulsiveness, and no-choice bioassays with different type of applications (soil, foliar, and soil-foliar) were used in order to evaluate performance and action of the product. evaluation of epidermal micromorphology and mesophyll structure of treated plants and elemental analyses of leaves were performed. in repulsiveness experiments, almost all dust treatments significantly inhibited mites from migrating to and/or settling on the treated leaf. In repellency experiments, foliar and soil dust treatments were not significantly different from control. Significant mortality was observed for all dust treatments in two-choice and in no-choice bioassays, suggesting mites are susceptible to rock dust by contact, and by indirect interaction through the feeding on plants subjected to soil application of rock dust. Leaf epidermal micromorphology and mesophyll structure of treated plants showed structural variation due to mineral accumulation, which was also confirmed by elemental analyses of leaves. These results demonstrate for the first time that granite rock dust interacts with two-spotted spider mites by modifying pest behavior and via acaricidal action, providing more insights in understanding the mechanism of this novel natural product as pest management tool. In the effort to find better alternatives to conventional synthetic pesticides and embrace reduce-risk strategy approaches in crop protection, mineral rock dusts offer an interesting option as natural products to prevent or control pests, diseases, and other plant pathogens, with a minimal impact on human health and the environment 1. Deployed as foliar spray application or as soil amendment, mineral-and dust-based products (such as diatomaceous earth) have been widely used in crop protection, with increasing interest in the agricultural sector as crop pest management tools 2-5. Rock dust is a valuable source of silicon (in the form of amorphous silica, SiO 2), which is one of the most abundant elements in the earth's crust. It has beneficial effects for plants under a range of abiotic and biotic stresses 6-8. Application of silicon in crops as a pre-harvest treatment provides a viable component of integrated management of insect pests and diseases as it does not leave pesticide residues in food or the environment, and it can be easily integrated with other pest management practices, including biological control 9,10. When a powdered siliceous mineral is shaken with water, particles from large colloids to simpler ions can be dissolved in the aqueous solution forming different complex (such as colloidal silicic and orthosilicic acids) 11,12. Silicon is absorbed by plant roots from the soil as monosilicic acid [(Si(OH)...

Evaluation of compounds for repellency of the multicoloured Asian lady beetle (Coleoptera: Coccinellidae) in vineyards

“…Carvacrol, Timorex Gold (highest rates), pine oil, and granite dust were highly effective and reduced the number of the beetles on grapes by more than 80%. The same granite dust was repellent to cabbage looper (Trichoplusia ni) (Lepidoptera: Noctuidae), diamondback moth (Plutella xylostella) (Lepidoptera: Plutellidae), and two-spotted spider mite (Tetranychus urticae Koch) (Trombidiformes: Tetranychidae) (Faraone et al 2018(Faraone et al , 2020. In our study, granite dust was more repellent than Fossil Shell Flower was.…”

Silicon-Mediated Enhancement of Herbivore Resistance in Agricultural Crops

“…Furthermore, the herbivore treatment combined with Si supplementation increased the number of glandular trichomes in tomato leaves 15 d after herbivory ( Figure 2A ). The effect of Si on herbivore-induced defenses in tomato has been scarcely studied, but induction of plant resistance has been reported (Faraone et al, 2020 ). There is also evidence that Si enhances resistance of tomato plants against pathogens.…”

Suitability of spider mites and green peach aphids as prey for Eriopis connexa (Germar) (Coleoptera: Coccinellidae)

“…However, the efficacy of this method is not always effective, since these pests become more prone to evolving pesticide resistance due to their high biotic potential and high genetic variability 3 , 4 , 6 , 7 . Intensification of chemical sprays has led also to environmental pollution, and poisoning risks to farmers and consumers 8 , 9 . For this reason, alternative control measures have been sought worldwide 9 – 11 .…”

“…Intensification of chemical sprays has led also to environmental pollution, and poisoning risks to farmers and consumers 8 , 9 . For this reason, alternative control measures have been sought worldwide 9 – 11 . Biological control is a potential alternative control method, mainly when combined with other control measures, thus helping to implement integrated pest management programs 11 , 12 .…”