First Report of Pheromone-Based Mating Disruption for Grape Mealybug ( <i>Pseudococcus maritimus</i> )

<h3>Abstract</h3> <h3>Background and goals</h3> <i>Pseudococcus maritimus</i> is the primary vector of grapevine leafroll-associated viruses (GLRaVs) in Washington State vineyards and can infest grape clusters. Neonicotinoids are used widely against <i>Ps. maritimus</i>, but resistance potential highlights the need for integrated pest management (IPM). Additional IPM strategies are needed to improve <i>Ps. maritimus</i> control, slow insecticide resistance, and mitigate GLRaV spread. <h3>Methods and key findings</h3> From 2021 to 2023, we deployed Pacific Biocontrol twist-tie pheromone dispensers on grapevines at 0, 25, 74, 148, and 247 dispensers per ha, and Trécé CIDETRAK GMB MESO dispensers at 0, 79, and 124 dispensers per ha. Male mealybug densities were monitored with Trécé <i>Ps. maritimus</i> lures in traps from May to October 2021 and from April to October 2022 and 2023. In all 3 yr, <i>Ps. maritimus</i> had two distinct flight periods but the timing and abundance of captured male mealybugs varied. Pheromone dispensers reduced peak trap captures, but no clear relationship was found between dispenser rate and <i>Ps. maritimus</i> capture. <h3>Conclusions and significance</h3> This study demonstrates that mating disruption has potential applications in an IPM program for <i>Ps. maritimus</i>. The timing of the two annual male flights indicates a single application of a passive dispenser lasting 4 to 5 mo, or a shorter-lived sprayable formulation could cover the seasonal period. A late-April pheromone dispenser deployment is recommended for Washington State. However, monitoring is encouraged to verify application timing on an interannual basis. The dispenser deployment rate requires further assessment as there was no significant difference (<i>p</i> &gt; 0.05) between the lower and higher deployment rates for male <i>Ps. maritimus</i> captures in sentinel traps.