Host Quality and Composition of Multihost Environment Impact the Maintenance of Members of the Wheat Dwarf Disease Pathosystem in Noncrop Areas

Harvest represents a challenge for the persistence of insect-transmitted viruses in agroecosystems. To overcome this challenge, some viruses infect noncrop plants as reservoirs for future introduction to newly sown fields. The wheat dwarf disease (WDD), one of the most important viral diseases on cereals, is caused by the wheat dwarf virus (WDV) and is transmitted by the leafhopper <i>Psammotettix alienus</i>. To better understand the contribution of noncrop species in the epidemiology of WDD, plant-virus (i.e., infection rate of WDV-b1 and WDV-w1 isolates) and plant-vector (i.e., survival and fecundity) interactions were monitored on 20 noncrop Poaceae (NCP) species. Results showed that (i) the host range of WDV is wider than expected and (ii) NCP can be clustered according to their host quality for WDV and/or <i>P. alienus</i>. This suggests that NCP species contribute differentially to the maintenance of members of the WDD pathosystem. In addition, <i>Bromus hordeaceus</i> and <i>Phalaris arundinacea</i> (two species with contrasted host quality for WDV and <i>P. alienus</i>) were included in multihost arena experiments to assess the impact of a heterogeneous plant environment on leafhopper preferences and WDV-w1 infection. Collected data showed that <i>P. alienus</i> prefers <i>B. hordeaceus</i> (a poor efficient host for WDV) for oviposition. This could lead to a dilution of viruliferous vectors in environments containing <i>B. hordeaceus</i> plants as hosts for WDV-w1. While the isolate-specificity of the dilution effect cannot be excluded, this study indicates that host quality and composition of plant populations are important for maintenance of WDV and <i>P. alienus</i> in noncrop areas.