Host quality and composition of multi-host environment impact the maintenance of members of the wheat dwarf disease pathosystem in non-crop areas.

Abstract

Harvest represents a challenge for the persistence of insect-transmitted viruses in agroecosystems. To overcome this challenge, some viruses infect non-crop 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 Psammotettix alienus. To better understand the contribution of non-crop 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 non-crop 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 P. alienus. This suggests that NCP species contribute differentially to the maintenance of members of the WDD pathosystem. In addition, Bromus hordeaceus and Phalaris arundinaceae (two species with contrasted host quality for WDV and P. alienus) were included in multi-host arena experiments to assess the impact of a heterogeneous plant environment on leafhopper preferences and WDV-w1 infection. Collected data showed that P. alienus prefers B. hordeaceus (a poor efficient host for WDV) for oviposition. This could lead to a dilution of viruliferous vectors in environments containing B. hordeaceus plants as hosts for WDV-w1. While the isolate-specificity of dilution effect cannot be excluded, this study indicate that host quality and composition of plant populations are important for maintenance of WDV and P. alienus in non-crop areas.