By Joey Slowik
The week of Nov. 11 was the Alaska Invasive Species Partnership meeting as well as the Farm Bureau and Sustainable Agriculture Research and Education meeting, both in Fairbanks, Alaska. So, this week I wanted to highlight a non-native pest which impacts agriculture, the Carrot-Willow aphid Cavariella aegopodii.
As the common name implies, the aphid is primarily a carrot pest. They feed on carrot greens and cause deformed leaves. They also create honeydew which is a sticky, sugary waste product secreted by aphids. Since they don’t have ant minders (which feed on the honeydew), this sweet waste often molds also hindering carrot growth. The aphids are also known vectors of carrot diseases such as carrot red leaf virus (CRLV) and carrot mottle virus (CMotV). The aphids look like an aphid and can be hard to identify as a Carrot-Willow aphid. They are only 2-3 millimeters long, green with brown antenna tips and some brown marks on their legs.
For most of the year these aphids feeds on willows. But in the summer months they will seek out a carrot family host. And domestic carrots seem to be attractive as there are usually many plants close together. Aphid populations can expand quickly as they can reproduce parthenogenically, that is without males. Towards the fall they will produce winged forms who will migrate back to willows and produce males and females. The males and females mate, and the females lay eggs that overwinter.
In the spring these adults will go back to reproducing parthenogenically for the summer and eventually migrate back to a carrot. They are commonly found across the Northern Hemisphere and there is some debate as to where they originated.
There are only some scattered records from the 1980’s in Anchorage and they don’t naturally occur in Alaska. They are found elsewhere at similar latitudes, so it could be we’re not noticing them or there are few people who can identify this type of aphid. Either way, something to keep an eye out for in the carrot patch.
Joey Slowik, IPM Technician, jaslowik@alaska.edu
