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New aphid’s presence grows in Northwest

The wheat grass aphid is the most abundant aphid in the Pacific Northwest.
Matthew Weaver

Capital Press

Published on July 11, 2018 8:53AM

The wingless form of the wheat grass aphid is the most abundant aphid in the region, a University of Idaho entomology professor says.

Brad Stokes/University of Idaho

The wingless form of the wheat grass aphid is the most abundant aphid in the region, a University of Idaho entomology professor says.


A new aphid has become more prevalent in the Pacific Northwest, and researchers are studying just how widespread it has become.

Researchers first discovered the Metopolophium festucae cerealium, or wheat grass aphid, around the Moscow, Idaho, area in 2011 during a study on climate change, said Sanford Eigenbrode, the University of Idaho entomology professor who led the study.

“It’s everywhere,” Eigenbrode said. “It’s the most abundant aphid you’ll find. Vigilance is merited because it’s new, and we’re getting all the information we can.”

The new aphid is called the wheat grass aphid because it likes wheat and most grasses, including oats and barley, Eigenbrode said. “Pretty much anything that looks like a grass is potentially a host for this aphid.”

Eigenbrode and researchers are conducting sweep-net sampling across the Northwest. Eigenbrode said three aphids were also found in Kansas, and he’s also asked for surveys of 20 sites in Colorado. He is still collecting data for this year.

Eigenbrode said the aphid’s activity this year is about the same as previous years. He’d like to install cages in fields to get an idea of the economic threshold for the aphids in a crop field.

Registered insecticides for aphid management will work to combat the new aphid, Eigenbrode said. At this time of year, wheat is at the stage where it doesn’t make sense to spray for any aphid, he said.

Twelve species of aphids attack the region’s cereals, Eigenbrode said. Farmers don’t necessarily differentiate between the different species, although treatment methods may vary.

The wheat grass aphid has caused more injury than other aphids in greenhouse studies, Eigenbrode said.

The aphid causes yellow or red stains on leaves. The stains are similar in winter wheat varieties but different in spring wheat. A UI student is studying the differences this summer to determine if there might be a range of vulnerabilities in different varieties, Eigenbrode said.

The aphid does not appear to be a vector for barley yellowdwarf virus.

The aphid originated in the United Kingdom, turning up in scientific papers in the 1980s. An informal survey found one in Boise in the 1990s, and then there was no further literature mentioning it, Eigenbrode said.

“Invasive species like this, often we get these intermittent records and then all of a sudden it blows up,” he said. “We don’t know if the intermittent records mean those tiny populations were just puttering along and suddenly blew up or if those disappeared and this is a new introduction of the same aphid, but this time it stuck. Both of those things can happen.”

Eigenbrode plans to seek funding to conduct further research. He expects to publish a pest alert about the aphid by the end of 2018.

Farmers concerned that they have the wheat grass aphid should contact Eigenbrode at 208-885-2972 or sanforde@uidaho.edu.



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