The Wheat Curl Mite (WCM), Aceria tosichella, belongs to the super family Eriophyoidae and is considered the principal Aceria species on cereal hosts. WCM are wingless, cigar-shaped and approximately 0.2 millimeters in length. WCM typically complete a life cycle in 8-10 days, and a single female is capable of laying 12-20 eggs. Under ideal conditions a single female can produce more than 3 million descendants within 60 days. WCM survival and population growth is optimal at temperatures of approximately 25 degrees C and generally limited by temperatures above 30 and below 15 degrees C. However, WCM can survive for a few months in cold conditions when reproduction is significantly lowered. Population growth and survival is also dependent on humidity, whereby WCM reproduction is greatest following periods of rain and warm temperatures. Unless found in extremely high numbers, WCM generally cause little direct damage in the field other than the characteristic leaf curling and the occasional trapping of the flag leaf. However, both immature and adult WCM transmit Wheat Streak Mosaic Virus (WSMV). To become viruliferous the virus must be acquired by the WCM during either of the two nymphal stages, typically after at least 15-30 minutes of feeding on infected plant material. Once infected the mite has the potential to transmit the virus to non-infected plants for at least 7 days.

Although wheat is the primary host of WCM, WCM have been recorded on more than 60 other plant species that may serve as alternate plant hosts. Infected volunteer wheat and alternate host plants provide both an effective “green bridge” refuge for WCM outside growing periods, and a potential source of re-infestation and spread of WSMV to successive wheat crops. Additionally, WCM has a large dispersal potential facilitated by wind. As a result, WCM survival and dispersal are the key factors influencing the spread of WSMV. Despite efforts to develop mite resistant wheat cultivars, primary management of WSMV focuses on reducing numbers of WCM through the control of volunteer wheat and alternate plant hosts.

WCM has been implicated as the vector of at least five viruses in addition to WSMV, including wheat spot mosaic virus, wheat spot chlorosis pathogen, cereal spotting, triticum mosaic virus, and high plains virus.

Watch Mites Move