North Carolina's blueberry growers are facing an emerging threat from a destructive beetle whose larvae feed underground, damaging plant roots and potentially killing blueberry bushes. Scientists have now identified the insect responsible, providing an important first step toward protecting crops from the pest. A research team at North Carolina State University has confirmed that the culprit is Prionus imbricornus, a species of longhorn beetle distinguished by its long antennae.
These wood-boring insects are becoming a growing concern for blueberry producers in the state. Female beetles generally deposit their eggs in soil near the roots of hardwood trees. After hatching, the larvae feed on the roots, sometimes destroying enough tissue to kill the tree.
The larvae can reach an impressive five inches in length, while the adult beetles do not feed. A Decade-Old Mystery Beneath Blueberry Fields North Carolina is the first state to document P. imbricornus feeding on blueberry bushes. However, signs of a similar problem have existed for years.
Reports of unidentified Prionus larvae damaging blueberry roots date back to 2010, but researchers had struggled to determine which species was responsible. Part of the challenge was the insects' underground habitat. Because the larvae remain near plant roots, they are difficult to locate and study.
Making matters more complicated, larvae from different longhorn beetle species often look remarkably similar, making visual identification unreliable. According to Kenneth Geisert, a graduate student in NC State's College of Agriculture and Life Sciences and lead author of the study, this uncertainty has made it difficult to develop appropriate pest control strategies. "Before now, researchers often just assumed the species of Prionus on their commodities based on adult identification," Geisert said.
"If that guess was incorrect, it could mean using a treatment strategy that did not line up with the problem and incorrectly associating species and their hosts. For instance, while P. imbricornus attacks roots, another type of longhorn beetle might attack the trunk of a tree, or dead branches. Without knowing which species of beetle you're dealing with and their ecology, incorrect management can cause adverse effects on non-target insects." To identify the insects, the research team conducted fieldwork at six blueberry farms in North Carolina's Pender, Sampson, Bladen, and New Hanover counties.
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