3/30/2023 0 Comments Walnut twig beetle![]() Researchers are concerned about the strong possibility for new associations among walnut trees and other twig beetles and fungi that exist in walnut's range that could result in similar diseases devastating to walnut. TCD and its spread may be due to the beetle's relatively recent range expansion to areas where walnut species (particularly eastern black walnut) did not co-evolve with WTB or the fungus. ![]() TCD is a threat to walnut in most of the western United States and, since 2010, has been detected in seven eastern states.Ĭurrent distribution of the walnut twig beetle (as of December 2014) based primarily on recent collections by the study's co-authors and various cooperators. Infected trees experience dieback of branches and may be killed in as few as three years. The result is Thousand Cankers Disease (TCD), so named because of the numerous cankers that form and cut off nutrient flow. WTB carries the Geosmithia morbida fungus and causes damage to walnut trees when it excavates under bark to feed and lay eggs, and, in the process, inoculates the tree with the fungus. "The discovery of two genetic lineages for walnut twig beetle is exciting because it implies that this pest may in fact be two species, one that has invaded many parts of the United States and one that is still largely resident to the foothill and mountain canyons of the desert Southwest," says Steven Seybold, PSW research entomologist. Hybridization did not occur in areas where WTB is believed to be native. In areas where WTB has become invasive, researchers found evidence of hybridization of the two genetic lineages. The most genetic diversity within these two lineages occurred in WTB populations in Western New Mexico and the Madrean Sky Island region of Arizona and New Mexico, where WTB is believed to be native. ![]() These researchers examined genetic variation in WTB samples from 62 counties in 13 states representing the beetle's current range and concluded that WTB descends from two geographically distinct genetic lineages in the Southwest.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |