Aphids & virus transmission in seed crops
Virus incidence in seed potatoes has a significant bearing on the quality (and hence classification and profitability) of the crop, and it is monitored during the crop inspections required for seed potato classification. Potyviruses (predominantly Potato Viruses Y and A) have become the most common viruses in the UK seed potato crop. Potyviruses are spread by aphids and the current control methods use insecticides to kill vector aphids. However, control of potyvirus spread is difficult because acquisition and inoculation can both occur in seconds before some pesticides can take effect.
FERA, Scottish Agronomy (SA), SAC. SASA and JHI
The objectives are as follows:
Identify the most important potyvirus vector aphids using a combination of laboratory/glasshouse and field studies.
Develop systems which effectively utilise aphid monitoring data and provide quality information for virus management programmes.
Identify sources of potyvirus inoculum and investigate their importance in the spread of virus to seed crops.
To obtain an improved understanding of the Estima-PVA interaction.
The results confirmed that Myzus persicae (peach-potato aphid) is generally more efficient at transmitting PVY and PVA than the other aphids tested. The Relative Efficiency Factor values (for PVY transmission) for some aphid species were revised. The REF values reflect the transmission efficiency of a particular aphid species in relation to that of the peach-potato aphid.
Field trials were designed to assess the timing of transmission and subsequent distribution of PVY and PVA in experimental plots. At one site, the interactions between different PVY strains and isolates were studied. This involved plants infected with PVY (serotypes O/C and N; and EU-NTN and NA-NTN molecular groups). The results suggest that the PVY isolates are likely to be transmitted by the same aphid species. The proportion of plants that tested positive for PVYN (in particular PVYEU-NTN) post-harvest was higher in comparison to other strains (PVYNA-NTN and PVYO). This apparent discrepancy between incidence at post-harvest and the weekly transmission rates for the PVYN and PVYO serotypes, suggests that PVYN transmission and detection in tubers is more readily observed for PVYN (PVYEU-NTN) than for PVYO in potato plants.
Trials' data were used to relate virus transmission to aphid counts for individual aphid species. The results suggest that the relationship between the aphid data and PVY transmission in the two sites (Edinburgh and York) may differ. The data collected at the two sites suggests that there may be differing relationships between yellow water trap catches and suction traps in different parts of GB.
A review of the use of mineral oils to minimise virus transmission highlighted knowledge gaps that were adressed in the related projects.
About this project
To identify the most important potyvirus vector aphids and sources of potyvirus inoculum, and to investigate the latter's importance in the spread of virus to seed crops.