Cal Poly mealybug problem persists



Agricultural officials plan to begin sampling urban gardens in the neighborhoods surrounding Cal Poly to see if a troublesome mealybug pest has spread away from the campus, according to Brenda Ouwerkerk, SLO County chief deputy agricultural commissioner.

Insect experts at a state lab in Sacramento have confirmed that passion vine mealybugs have now been found in three greenhouses at Cal Poly, including a Biological Sciences greenhouse about 1/4 mile away from the Ornamental Horticultural greenhouses where the sucking insect was first discovered.

The plant pest attacks around 300 commercially-grown crops, including grapes, citrus, avocados, and strawberries, and has no natural predators in this country. Although agricultural inspectors have found it at U.S. ports-of-entry, the passion vine mealybug has never been seen before in the continental U.S. until alert county ag inspectors discovered it at Cal Poly earlier this month.

A federal quarantine was placed on Cal Poly’s greenhouses, prohibiting entry or removal of plants while more mealybug samples are analyzed. Identification of the tiny worrisome pest is a time-consuming and difficult process, and is still ongoing at the Sacramento lab. With more than 5000 species of mealybugs, identification involves a complicated scoring system based on the numbers of ducts and pores, and the exact length of appendages.

The quarantine has recently been lifted on some campus greenhouses that have been declared free of the passion vine mealybug, allowing students to continue with their plant projects. Students were denied entry under the quarantine because mealybugs go through an active crawling stage during their lifecycle, and could move onto shoes or pants. Crop land at Cal Poly is also being sampled for the insect pest, with analysis ongoing at the state lab.

Agricultural officials are still investigating where the mealybug pest may have originated, according to Ouwerkerk. “Trace-back,� as ag officials call it, can be problematic, and Cal Poly’s record-keeping on the origins of its greenhouse plants has not been able to pinpoint the source.

Checking the surrounding neighborhood gardens for mealybugs could begin this week, depending on staff availability and the weather, the deputy ag commissioner says. ∆

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