Pasture Mealybug, a New Invasive Pest, Confirmed in Louisiana

By Tobie Blanchard

LSU AgCenter

BATON ROUGE, La. — LSU AgCenter researchers have confirmed the presence of a new invasive insect in Louisiana sugarcane fields. The pasture mealybug was detected in Vermilion and Iberia parishes late last year, raising concerns among growers, ranchers and researchers.

Blake Wilson, AgCenter entomologist, said the insect was observed by crop consultants Nick Daigle and Ryan Viator, who noticed a yellowing canopy in commercial sugarcane fields. AgCenter researchers collected specimens from the Vermilion Parish fields.

“Specimens were sent to U.S. Department of Agriculture Animal and Plant Health Inspection Service, where scientists with the National Identification Services were able to confirm the species identification based on morphological characteristics and genetic comparison with specimens collected from Texas,” Wilson said.

Fields in Louisiana where the pasture mealybug was detected showed severe yellow canopy syndrome and suffered severe yield loss, Wilson said.

“The pest status of H. summervillei in sugarcane is not well understood. Evidence from Australia has noted that both nymphs and adults are found on the leaves and roots of sugarcane,” Wilson said. “Only the nymphs are thought to feed. This feeding may be associated with yellow canopy syndrome, but the mealybug has not been identified as the direct cause of the symptoms.”

Sugarcane fields in St. Landry Parish also expressed yellow canopy symptoms, but Wilson said it is not known if the pasture mealybug was present there.

The insect was detected in Texas, where pasture dieback was reported in 22 counties, last year as well. As the name suggests, the pasture mealybug is known to kill various species of pasture grass used in livestock production.

“Early symptoms of infestations in pasture grasses cause discoloration ranging from yellowing to reddening,” Wilson said.

AgCenter researchers will conduct surveys to determine where the pasture mealybug may be in Louisiana sugarcane fields and pastures.

Potential host plants include all species of pasture and turfgrasses in addition to sugarcane. Suspected infestations of pasture mealybug should be reported to Wilson (bwilson@agcenter.lsu.edu) for sugarcane and Ed Twidwell (etwidwell@agcenter.lsu.edu) for pasture.