APPS Potato Disease Workshop Auckland 25Nov2013 Detecting potato viruses & insecticide resistance in aphids in water-propylene glycol yellow traps Ron van Toor Gaynor Malloch Brian Fenton
Major potato viruses Virus % fields infected % yield Luteovirus Circulative PLRV UK Certification 2011 NZ J Fletcher 2011 losses (Hamm & Hane 1999; Noite & McIntosh 2006) 14 14 80 Potyvirus Stylet-borne PVY 10 20 38 PVA 10 29 24 E Anderson SA PVA Estima PVY N PVY NTN PLRV
Aphid-virus vectors suction traps 1981-2009» UK Crop - Aphids V-E Potato Myzus persicae (ins-resist) 1.0 Macrosiphum euphorbiae 0.2 Cereal Metopolophium dirhodum 0.3» NZ Canterbury Rhopalosiphum padi 0.4 J Pickup SASA
Aphid trapping service - Scotland» ~140 yellow-bowl water traps serviced/week» Aphids identified to species» Web site on aphid flights/virus risk» Growers may respond with insecticides» Need information on virus & resistance incidence to decide on insecticide use
Virus detection method» RNA extraction from single or bulked aphids in TriPure» RTPCR PLRV + nested PCR PVA, PVY PVY PLRY PVY PVA PVY PLRV PVA bp 900 692 500» Fragments expressed on acrylamide or agarose gels (qpcr) 404 320» Sensitive for 1:20 virus-free aphids 242 190
Using trap data: Virus incidence» %Virus-carrying winged Aphids aphids N aphids %PVA %PVY M. dirhodum 6054 1.4 0.5 H. lactucae 30 0.0 7.2 M. persicae 2 0.0 0.0 Other species 379 0.0 0.3 PVY
Using trap data: Insecticide resistance in M. persicae MS G-type OP Carbamate Pyrethroid A R3 MACE Kdr/S-kdr B R1/R2 MACE Kdr/S-kdr H S/R1 MACE Kdr M R2 MACE - I, J S/R1 - - O S/R1 MACE - Results PVY Aphid: Susceptible Carbamate/pyr ethroid resistant PVA MACE Kdr r/s B. Fenton Test: Virus OPs Carbamate Pyrethroid Virus OPs Carbamate Pyrethroid
Insecticides used» UK < 8 foliar applications of:» Pyrethroids» Pyridine azomethine» Neonicotinoid?» Dimethyl-carbamate» NZ (K Hughes McDonald Alex Merchants 2012)» Neonicotinoid seed dressing» Spray oils & 3 8 foliar applications of:» Pyridine azomethine» Organophosphates» Pyrethroids» Dimethyl-carbamate» Neonicotinoid» Tetramic acid» Tetronic acid» Avermectin» Silicon dioxide» Spinosoid
Using trap data: Grower decision concept NA extract from aphids in traps Virus test on bulk (1 20) Other aphids M. persicae No virus or PVA, PVY No insecticide PLRV, no M. persicae λ-cyhalothrin PLRV, M. persicae Test for resistance/genotype in individual M. persicae None MACE kdr Esterase 2-3 &/or MACE + kdr Molecular tests Any insecticide λ-cyhalothrin pirimicarb pymetrozine flonicamid thiacloprid acetamiprid
Conclusions» Potential use of traps in monitoring virus incidence and insecticide resistance in aphids on potatoes» Limited as a tool for growers» Modified to NZ conditions (Tomato potato psyllid; insecticide availability)
Acknowledgements» Funding» Marie Curie Fellowship Oct 2008 Sep 2010» Scottish Potato Council» James Hutton Institute» Jim McNicol statistical analysis» Plant & Food Institute (CFR)» Leave of absence to complete Fellowship
www.plantandfood.co.nz Ronald.vanToor@plantandfood.co.nz
Virus transmission Water/PG 50%» Cage A: 12 virus-fed winged aphids + 20 clean wingless aphids» Cage B: 20 clean wingless aphids» 4 reps, traps weekly over 3 weeks» %PVY-carrying aphids Wk Wing 0d Wing 7d Cage B 1 71 24 0 2 13 21 0 3 8 31 1 /4 cages Cage A Cage B