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Pseudococcus maritimus status as an economic pest increased substantially after it was identified as a key vector of most grape vine leafroll-associated viruses (GLRaVs). Of these viruses, GLRaV-3 is the most economically destructive. Current control recommendations for slowing the spread of GLRaVs include one to two applications of insecticides to reduce vector populations. Systemic insecticides require the insect to feed before death or paralysis occurs. It was unknown if systemic insecticides could paralyze or kill P. maritimus quickly enough to reduce their ability to vector GLRaVs. Hence, we tested imidacloprid, spirotetramat, and flupyradifurone to see if these insecticides would have any effect on P. maritimus’ efficiency to vector GLRaV-3 on treated grapevines. We conclude that these systemic insecticides do not convey any additional protection to grapevines. However, these insecticides are still useful for reducing vector populations and indirectly reduce the potential spread of GLRaVs among vines in vineyards.

The grape mealybug, Pseudococcus maritimus (Ehrhorn; Hemiptera: Pseudococcidae), is the primary vector of Grapevine Leafroll associated Viruses (GLRaVs) in Washington State vineyards. Rearing laboratory colonies of grape mealybug has proven difficult. Several host plants were tested to determine their suitability for use as an alternate host plants for laboratory colonies of grape mealybug. Of the plants tested, colonies of grape mealybug were successful on pumpkin (Cucurbita pepo cv 'Connecticut field') leaves and vines. Mealybugs were able to develop from the crawler stage, through developmental instars, and adults were able to reproduce viable offspring. To date this is the only successful study to raise grape mealybugs on a cucurbit. Pumpkin appears to be a viable alternate host plant for laboratory colonies of the grape mealybug.