(Photo by L.M. Diepenbrock, UF/IFAS)
One of Lauren Diepenbrock’s props at a Jan. 14 OJ break at the Citrus Research and Education Center was a paper plate bearing the message “Easy diagnostic: smashed lebbeck mealybug = purple guts.”
Diepenbrock, a University of Florida Institute of Food and Agricultural Sciences (UF/IFAS) entomologist, explains the meaning of the plate’s message. UF/IFAS researcher Lance Osborne found a lebbeck mealybug, a relatively new pest of Florida citrus. “He smashed it in the field and it turns out that its guts are purple,” says Diepenbrock, who now tells growers that a grove bug with purple guts is almost certainly a lebbeck mealybug.
The lebbeck mealybug was first found in Florida citrus in Highlands County in 2019. It has since been found in groves in DeSoto, Hardee, Hendry, Lee and Polk counties. The pest’s feeding causes fruit blemishing, leaf damage and excessive sooty mold buildup. It has been a major cause of fruit drop in other countries and can cause tree death in new plantings.
Sooty mold is a key indicator of lebbeck mealybug in a grove. “You look for high areas of sooty mold,” Diepenbrock says. “You look up.” Sooty mold on bags used as individual protective covers that exclude HLB-spreading psyllids from young trees is also a clue that lebbeck mealybug is on the tree.
Diepenbrock says several types of chemicals give “good contact efficacy” against lebbeck mealybugs. Literature from other countries indicates the best long-term control could come from beneficial insects such as ladybugs. “Ground management of ants is probably something we’re going to need to work on,” she says, explaining that ants are thought to move mealybugs to new host trees and protect the pests from predators. She says she hopes that “a combination of insecticides and predators” will provide a comprehensive management program.
Diepenbrock urges growers who think they may have lebbeck mealybugs in their groves to contact her or their citrus Extension agents, so researchers know where the pests are.
The OJ break where Diepenbrock provided the lebbeck mealybug update was hosted by citrus Extension agent Chris Oswalt at the Citrus Research and Education Center in Lake Alfred, Florida.
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