Project Number: 2092-22000-022-034-T
Project Type: Trust Fund Cooperative Agreement
Start Date: May 1, 2022
End Date: Jun 30, 2024
Our goal is to identify additional aphidicides with the potential to manage potato leafroll virus (PLRV) and/or potato virus Y (PVY) transmission by the green peach aphid (Myzus persicae) in potatoes. We hypothesize treatments limiting phloem-feeding will decrease PLRV transmission and those which reduce settling behaviors will decrease PVY. Objective 1: Quantify differences in how readily green peach aphids acquire and inoculate PLRV or PVY following treatments of sulfoxaflor, flonicamid, spirotetramat, afidopyropen, or a water control. Objective 2: Determine whether green peach aphids exhibit varied settling behavior on potato plants following treatments of sulfoxaflor, flonicamid, spirotetramat, afidopyropen, or a water control.
We will use two approaches: controlled assays which will test the direct impact of the insecticide on the physiological acquisition of the virus, and a no-choice arena to test the behavioral effects of insecticide treatments on aphid settling on potato plants, as this behavior has a strong influence on virus spread within a field. To address Objective 1, controlled PLRV acquisition assays will involve placing non-viruliferous green peach aphids within a clip cage on a treated potato plant leaf for 48 h, after which surviving aphids will be moved onto a healthy, untreated indicator plant individually for 5 d prior to removal. Indicator plants will be tested for PLRV. For PVY, we will follow protocol described in Boquel et al. (2014), placing up to 35 GPA on the stem of a PVY-infected potato plant. Aphids leaving or falling off the stem within a 4-h period will be collected and assayed for PVY. Controlled PLRV inoculation assays will involve placing individual viruliferous green peach aphids carrying PLRV on uninfected, treated potato leaves within clip cages for 48 h, after which they will be removed, and the plants tested for PLRV infection. For PVY, non-viruliferous green peach aphids will be placed on the stem of an untreated PVY-infected potato plant for 10 min and transferred individually to a clip cage on the leaf of a treated potato plant for 1 h prior to removal. The potato plants will subsequently be tested for PVY infection. To address Objective 2, we will use assays similar to those described in Eigenbrode et al. (2002) and Gadhave et al. (2019) to quantify immigration and emigration rates to and from treated potato plants. To assess immigration rates, we will release 50 adult winged aphids, or alates, at the far end of a no-choice arena across from which will be a treated potato plant leaflet. For emigration rates, we will release 50 alates on a treated potato plant leaflet and allow them to disperse to the other, empty end of the arena. The alates in both assays will be observed every 10 min for an hour, and all those immigrating or emigrating will be recorded and removed from the arena.