Wheat curl mites’ only claim to fame is their ability to vector wheat streak mosaic virus (WSMV) but it’s severe enough to take these mites and their indirect effects on wheat very seriously. A recently funded research project is exploring the possibility of wheat resistant to these mites and we need your help in locating sites in South Dakota with WSMV infections and likely infestations of the wheat curl mites.
Wheat curl mite, Aceria tulipae (Acari: Eriophyidae), is a microscopic plant-feeding mite. These mites are 1/100” long, have spindle-shaped bodies, and two pairs of legs. They are very hard to see and even a 10X lens may not be enough. Populations of these mites increase at the greatest rate in temperatures between 75°F and 80°F. Wheat curl mites become active in the spring and continually move to young, newly emerged leaves. Mites prefer the upper surfaces of leaves, and lay their eggs along the leaf veins. Actively growing wheat is their preferred host, and as wheat matures, wheat curl mites move to the top of the plant and depend on wind to carry them to over-summering hosts, such as volunteer wheat or other grasses. When their summer hosts mature and dry out, mites move back to newly emerged winter wheat or volunteer wheat.
In the fall, maintaining a volunteer wheat-free period of at least two weeks is the only way to try to prevent their infestations and infection with WSMV because there are no insecticides or miticides that kill these mites. Even with these preventative measures many acres of wheat get infected with WSMV every year and suffer significant yield losses. Wheat curl mites prefer young, fast growing wheat and grasses, and once wheat matures the mites move onto nearby vegetation. They come back to the fields if volunteer wheat is around but they can also be blown in on wind currents from neighboring fields. There is an abundance of potential hosts for wheat curl mites and thus preventing wheat curl mite infestations and WSMV infections is a great challenge.
One of the long-term sustainable approaches to curbing wheat curl mites’ impact on the crop is development of wheat that is resistant to the mites. This work is very tedious and it is a long process but it’s underway at Kansas State University. South Dakota is collaborating with K-State on this project, and one of the goals is collecting diverse populations of wheat curl mites from the entire Midwest and Northern Plains area in order to capture full diversity of these mites in the region. This is where we need your help: we need to locate sites with WSMV infections to collect mites from those areas. All we need is information on a location, and we will collect the samples. If you have a confirmed WSMV infection, please get in touch with me at any point this summer (Ada Szczepaniec: 605-688-6854). This is a very promising research, and with some luck will be very valuable for wheat producers in the region.