The allium leafminer, a tiny but destructive insect, was identified in leeks and onions in Lancaster County in south-central Pennsylvania, say Penn State entomologists. “This is the first confirmed infestation in the Western Hemisphere.”
The infested leeks and onions were collected last December from an organic farm, where the owner reported a 100-percent loss of leeks, onions and chives, and who said the pest had been present for several years, according to lancasteronline, a news site. “Already, a quickly launched survey by plant inspectors for the state Department of Agriculture has discovered the pest also in Chester, Dauphin, Delaware, Lehigh and Delaware counties.”
In a “pest alert,” Penn State said the allium leafminer attacks leeks, onions, garlic, chives, shallots, and green onions. The insect punctures leaves and tunnels into the plants. The punctures and tunnels allow bacteria and fungi into the plant. “The literature suggests organic production and market garden production systems tend to be most at risk, perhaps due to insecticidal control in conventional production systems,” said Penn State. Lancasteronline said the leafminer is native to Poland and Germany and has spread to other parts of Europe and to Asia in the past decade.
The allium leafminer, Phytomyza gymnostoma Loew, also is called the onion leafminer. A different insect, Liriomyza spp, also called the onion leafminer, is present in California.