Project description

Pea necrotic yellow dwarf virus (PNYDV) is a nanovirus species that has only been known since 2009, and much information is still lacking about its epidemiology. The virus is transmitted by aphids and infects legumes. It is known from nanovirus species in warmer areas that they occur epidemically at intervals of a few years, and can cause total failures in legumes. Within the project, natural infections with PNYDV were detected in the field on several legume species. Pea, vetch, field bean, lentil, spring vetch, Pannonian vetch, chickpea, and rough-hairy vetch were confirmed as host plants for PNYDV. Rough hairy vetch could be determined as host plant for PNYDV for the first time in Austria among the weeds.

Results

One of the most important vectors for PNYDV is the green pea aphid. In the experimental years 2019 and 2020, the number of occurring green pea aphids was determined in the different legume species. Most individuals were found on pea, vetch, spring vetch, shaggy vetch, alfalfa, lentil, horn clover, earth clover, Persian clover, incarnate clover, and fenugreek. As it appears, the green pea aphid colonizes plots with its "favorite food plants" quite selectively, regardless of the location of the plot in the experiment and neighboring plots. This indicates that the attractiveness of individual legume species to the green pea aphid varies widely.

Treatment trials in organic field bean showed that the attractiveness of different field bean varieties to the green pea aphid and black bean aphid also differed. The field bean-oat mixed-crop trials showed that the number of aphids and the number of virus-infested plants were lower in field bean-oat mixed-crop stands than in field bean pure-crop stands. In grain legume cultivation, mixed cropping is an important strategy for the future to improve the yield stability of grain legumes, especially under changing climatic conditions.

Summary

Within the NANOVIR project, a wide variety of legume species could be confirmed or detected as host plants for PNYDV. The attractiveness of different legume species but also varieties for the green pea aphid is very different. In mixed crops, the number of aphids and virus-infected plants is lower. However, there are still many questions to be answered for the application in practice, such as what are regionally suitable mixed crop partners, which varieties are suitable for what, or also which position and which effects mixed crops have in the crop rotation.

Benefit of the project

PNYDV has only recently appeared in our latitudes. Since infections with PNYDV in peas and field beans can result in total failures, research into the nanovirus is of great importance. In the course of this project, the epidemiology will be investigated in order to develop suitable control strategies.