APP203853: To release the parasitoid, Pauesia nigrovaria, as a - PowerPoint PPT Presentation

APP203853: To release the parasitoid, Pauesia nigrovaria, as a biological control agent for Tuberolachnus salignus (the giant willow aphid) Stephanie Sopow, Scion; Barry Foster, Apiculture New Zealand; Dr Carl Wardhaugh, Scion 24 October 2019 Photo: osborn88

GWA Project Team:

Biology of giant willow aphid  Tuberolachnus salignus (GWA)  Features: • Largest known aphid (6 mm) • Only females are known • Live birth (no eggs) • Can live for up to 3 months (cool temps) • Scarce in spring  In New Zealand since at least 2013  Host are willows, poplars, apples, pears… widespread in NZ – both rural and urban  Stem feeder – ingests plant sap and secretes honeydew – honeydew ‘rain’ Photo: ‘shineybeetleman’

Impacts of GWA on apiculture in NZ  Barry Foster, Apiculture NZ

Impacts of giant willow aphid on Apiculture  Barry Foster  Apiculture New Zealand  In support of submission by Stephanie Sopow & Carl Wardhaugh from Scion on APP203853 to release Pauesia nigrovaria as a bio- control of the giant willow aphid

Impacts on bee health  Threat to critical spring pollen and nectar supplies.  Willow found in most areas of NZ – provides volume of pollen for hive spring build up  Helps to build hives up for pollination and honey flow.  Willow honey dew provides carbohydrates for vespula wasps which prey on hives in autumn when the aphid and vespula wasps are at their maximum populations.

Impacts on bee products  Cement honey 30% loss or more on extraction.  Clogged filters & process equipment  Potential down grade mono floral honey to honey dew honey  Bees cannot digest melezitose in willow honey dew

Willows as fundamental risk management tools  Stanley Braaksma, New Zealand Poplar and Willow Research Trust

Evidence of the direct impacts of GWA on willows  Stephanie Sopow (Scion) presenting the work of Dr Trevor Jones, Plant & Food Research

Aphid populations on unsprayed trees 5 April S. candida S. eriocephala S. lasiolepis S. lasiolepis × viminalis S. purpurea S. schwerinii S. viminalis S. × reichardtii S. alba S. lasiandra S. matsudana S. matsudana × alba S. matsudana × alba S. matsudana × lasiandra S. × fragilis Crack willow 0 20 40 60 80 100 Percentage of trees Aphids >300 100-300 50-100 20-50 5-20 <5

Willow poles supplied for soil conservation Willow clones Tangoio Matsudana 6% Moutere 10% Kinuyanagi Hiwinui 53% Booth Holland 25% Irette Glenmark Aokautere Viminalis

Willow field trial at Massey University

Survival of willow trees after 2 years of GWA infestation S. candida S. eriocephala S. lasiolepis S. lasiolepis × viminalis S. purpurea S. schwerinii S. viminalis S. × reichardtii S. alba S. lasiandra S. matsudana S. matsudana × alba S. matsudana × alba S. matsudana × lasiandra S. × fragilis 0 20 40 60 80 100 Survival (%) t Aphids No Aphids

Height growth of willows 2018-2019 S. candida * S. eriocephala S. lasiolepis S. lasiolepis × viminalis S. purpurea S. schwerinii S. viminalis * S. × reichardtii S. alba S. lasiandra S. matsudana * S. matsudana × alba * S. matsudana × alba * S. matsudana × lasiandra * S. × fragilis 0 50 100 150 200 Height growth (cm) t Aphids No Aphids * Significant difference (p < 0.05)

GWA caused reduction in height growth GWA No GWA www.scionresearch.com Prosperity from trees Mai i te ngahere oranga Scion is the trading name of the New Zealand Forest Research Institute Limited

GWA caused delayed spring flowering GWA No GWA

GWA caused reduction in flower catkin size infested healthy Not seen until spring of second year – willows gather and store energy in autumn, but GWA siphoning off resources – infestation is having a cumulative effect

 GWA reduced above ground biomass to less than half that of the controls after 9 weeks of infestation  GWA continued to influence the trees after the aphids were removed – new shoots dehydrated  Dramatic reduction in root growth, and also decreased the mass of previously developed woody tissue

Environmental and economic impacts of GWA in New Zealand  Stephanie Sopow, Scion

Direct and indirect effects of GWA have numerous consequences  Direct harm to host trees  Honeydew leads to poor bee health, bad honey  Sooty mould grows on honeydew coated surfaces • Photosynthesis • Fruit exports – kiwifruit • Wool – sheltering sheep • Nuisance  GWA honeydew is causing an increased abundance of vespid wasps • Wasp expert Professor Phil Lester of Victoria University: “The rapid spread of the invasive willow aphids, which have arrived in this country in the past few years, have made the wasp problem even worse than it would otherwise have been”.

The ‘bad wasps’  Bee killers & honey thieves  > 80,000 hives lost annually  Predators of native insects & birds – affecting NZ’s biodiversity  Health risk  Now more widespread than ever

Beekeeper survey results Saw crystalised 74% honey in the comb Experienced 50% Have seen 41% honey losses death of some (of those that of these saw crystals) willows 54% Have seen Chose to 61% blackened remove honey stems or early to avoid branch issues with dieback of crystalised willows honey Chose to move Saw more hives further wasps robbing 80% 80% from willows to hives & avoid predating on crystalised bees honey

Economic losses related to GWA estimated at $300 million per year  Damage to willows & poplars (reduced root production and overall biomass) – $145.8 m Dr Melissa Welsh • Reduction in mitigated erosion • Carbon losses  Honey losses – $84.2 m • Wasp impacts on production • Wasp management costs • Cement honey  Other wasp impacts – $64.4 m • Reduced clover nitrogen fixation – wasps disrupting pollination by interfering with bees • Health costs and traffic accidents Sooty mould – $5.5 m  • Kiwifruit losses

Estimated benefits of Pauesia nigrovaria  Other species of Pauesia have been used as BCAs with great success – e.g. black pine aphid in South Africa reduced number of infested trees from 99% to 2% within 2-3 years after release of Pauesia cinaravora  Simulations based on observations and best estimates of GWA and P. nigrovaria fecundity suggest we could see a similar outcome in NZ  Modelled interaction between P. nigrovaria and GWA using methods commonly used to model population growth and economic impacts (simulations with and without P. nigrovaria to estimate its effect)  Predictions: • 1% reduction in GWA in 1 month • 34% after 1 year • 80% once parasitoid ‘catches up’

Cumulative value of P. nigrovaria as a BCA  Mean value over a 20 year period = $1.5 billion

Selection of non-target aphid species for host testing  Dr Carl Wardhaugh, Scion

New Zealand Aphids – an overview of their diversity and vulnerability to P. nigrovaria  Goal of host testing – to determine the potential vulnerability of non- target aphid species, especially natives, to P. nigrovaria  Over 130 aphid species from 11 subfamilies established in NZ  But just 15 species are native, representing three subfamilies  ~115 introduced pests of exotic plants  Used selection criteria recognised as best practice for classical biological control, to select non-target aphid species for testing: • Close relatives (the most likely to be attacked) • Native species (representatives of native lineages) • Similar size to target (GWA is large) • Similar appearance (body shape, colour) • Similar biology (attacks the arboreal parts of the same trees)

Giant Willow Aphid – Vital Statistics  The world’s largest aphid (5.8 mm long, and robust)  Attacks stems and branches of willows and poplars  Grey and black  A member of the subfamily Lachninae, the most primitive group of aphids • Since Lachninae branches early from the aphid family tree, they are not closely-related to any other group of aphids

Aphid Phylogeny An unrooted topology of the family Aphididae. From Novakova et al. (2003)

Pauesia nigrovaria – Vital Statistics  A member of the Braconid subfamily Aphidiinae • All Aphidiinae wasps only attack aphids  Pauesia species are known to specialise on aphids in the subfamily Lachninae  P. nigrovaria is only known to attack GWA in its native range  3-4 mm in length – much larger than any of NZ’s native aphid species

Host Selection – Lachninae  The subfamily to which GWA belongs  Represented in NZ by 8 introduced pest species • 2 spp. on pines are very small (<2.5 mm) • 5 Cinara spp. on cypress and juniper are larger (up to 4.5 mm), attack stems, and are grey and black • Selected species: Cinara fresai − Widespread, large, Reared on Cupressus cuttings − If P. nigrovaria attacks anything else, it should be this