Foliar uptake, systemic translocation and pest control efficacy of acetamiprid in combination with biostimulants and adjuvants on grapevines

In major European viticultural areas, insecticide treatments are applied to control Scaphoideus titanus , the main vector of Grapevine flavescence dorée phytoplasma. The recent ban from the European market of some effective active ingredients highlighted the need to optimize the performance of the remaining commercial formulations. While adjuvants are often added as auxiliary substances to enhance the performance of pesticide spray mixtures, the beneficial effect of biostimulants have received less attention. In this study, we evaluated spray applications of acetamiprid, a systemic neonicotinoid insecticide, in combination with tank-mix biostimulants and adjuvants, assessing insecticide foliar uptake and systemic translocation over time, as well as pest control efficacy against S . titanus under semi- and open-field conditions. Acetamiprid concentrations in leaves increased progressively after 1, 24, and 72 h for all treatments, although only the biostimulant containing Ascophyllum nodosum extracts and an organosilicone-based adjuvant showed significantly higher concentrations within the first 24 h. Treatments combined with humic acids and plant-derived amino acids significantly enhanced insecticide systemic translocation after five days from application, although higher concentrations were observed in leaves at the 4th-5th nodes compared to the shoot apex for all treatments. Under field conditions, acetamiprid provided substantial control efficacy when combined with brown seaweed extracts, humic acids, and an anti-drift adjuvant, maintaining insecticidal activity for up to ten days after treatment. These findings highlight the potential of integrating plant biostimulants with insecticide treatments due to their ability to influence insecticide dynamics and preserve efficacy, while also providing beneficial effects on plant nutritional processes.