Virus Acquisition and Retention Periods for Transmission of Triticum Mosaic Virus by the Wheat Curl Mite

The wheat curl mite (WCM), Aceria tosichella Keifer, is an important pest of winter wheat (Triticum aestivum L.) in the North American Great Plains region because of its ability to transmit three important viruses to wheat. Wheat streak mosaic virus (WSMV; Tritimovirus tritici) has been the most studied of these three viruses, but the rapid spread of Triticum mosaic virus (TriMV; Poacevirus tritici) throughout the region, along with its synergistic relationship with WSMV, has increased the need for a more complete understanding of its transmission capabilities and epidemiology. Studies were conducted to determine the acquisition and retention periods of TriMV by the WCM. TriMV acquisition by the WCM began after just 1 h of feeding, but transmission occurred at a low efficiency (2.9%). Transmission efficiency increased to a maximum level (32%) by 24 h of feeding. The virus retention period was determined by holding viruliferous adult mites on a good mite host, but one that is a nonhost for TriMV (barnyardgrass). After a base transmission rate of 40% when the retention study was initiated, transmission rates declined to 2% on day 6 and 9% on day 8. This study is the first to document the acquisition and retention characteristics of TriMV by the WCM and demonstrated that these characteristics are similar to those previously determined for WSMV transmission by the mite. The study also verified that WCM adults are incapable of acquiring and subsequently transmitting TriMV, and thus, the virus must be acquired by immature mites. Establishing transmission characteristics for the viruses in the wheat mite–virus complex is critical for a complete understanding of plant–vector–virus interactions and their influence on the epidemiology of this complex.