Efficacy of steam and hot water disinfestation treatments against genetically diverse strains of grape phylloxeraDaktulosphaira vitifoliaeFitch (Hemiptera: Phylloxeridae) on viticulture equipment and machinery

Abstract

Background and Aims In Australia, hot water immersion and steam application are recommended disinfestation strategies for harvesting bins, vineyard machinery and vehicles against grape phylloxera, Daktulosphaira vitifoliae Fitch. This study validated the effectiveness of these two strategies against genetically diverse phylloxera strains. Methods and Results The first instars of six phylloxera genetic strains, G1, G4, G7, G19, G20 and G30, were subjected to steam projected from 8 and 24 cm, and from 92 cm for G1 only, for 10, 20 and 30 s. All steam treatments achieved 100% mortality across the six genetic strains. The efficacy of hot water treatment (HWT) against phylloxera was investigated by immersing first instars in a water bath set at 22, 40, 45, 50, 60 and 70°C for 60 and 120 s. Treatments of 50°C and above for a minimum of 60 s resulted in 100% mortality across the six genetic strains. Survival was observed at 40 and 45°C, and first instars subsequently established feeding sites, developed into adults and reproduced on excised grapevine roots. Conclusions Steam application and HWT, as currently recommended in the Australian National Phylloxera Management Protocol, are effective for disinfestation of diverse phylloxera strains. Significance of the Study This study has validated, for the first time, the efficacy of steam application and HWT against phylloxera first instars and highlights the potential to lower the recommendations for treatment duration and water temperature disinfestation while still achieving 100% mortality.