UNIVERSITY PARK, Pa. -- An insect never before found in the Western Hemisphere has been discovered in Pennsylvania, and agriculture officials are asking growers and home gardeners to help monitor and manage the new invasive pest.
The allium leafminer -- also known as the onion leafminer -- is a threat to several species of crop plants in the genus Allium, such as onion, leek, garlic, chive, shallot and green onion, warned Shelby Fleischer, professor of entomology in Penn State's College of Agricultural Sciences. He noted that the insect's full range of host plants is unknown.
"More study is needed to assess the potential impact of allium leafminer under Pennsylvania conditions, but literature from other countries suggests that organic and market-garden production systems and home gardens tend to experience more damage than conventional production systems," Fleischer said.
"Conventional growers may have fewer problems due to the insecticidal controls they are likely to use and to shorter time windows in which host plants are available," he said. "However, wild Allium species that exist as weeds in our agroecosystems may alter this."
The allium leafminer's first U.S. appearance was in Lancaster County, where it was found infesting leeks and onions. The Pennsylvania Department of Agriculture reported that it since has been discovered in Lehigh, Chester, Dauphin and Delaware counties.
Native to Germany and Poland, the allium leafminer's geographic range recently has been expanding rapidly, most likely transported with commercial cargo, in shipments of affected crop plants or in passenger baggage, according to state agriculture officials.
"It is now present throughout Europe, reaching the United Kingdom in 2004," Fleischer said. "It recently has been reported in Asia, Turkey, Russia and Turkmenistan."