Risk of Eucalyptus tortoise beetle control Jon Sullivan Jon - - PowerPoint PPT Presentation

Risk of Eucalyptus tortoise beetle control

Jon Sullivan Jon Sullivan

Biology of the pest in NZ

• Adults and larvae strip all

flush, young leaves from hosts

• Each female can lay ~

2000 eggs

• At least two generations

per annum results in rapid population expansion

• First generation needs

biological control to

• ptimise tree growth

Egg parasitoids Enoggera nassaui and Neopolycystus insectifurax provide good control of 2nd generation eggs in NZ: Egg survival 4% Egg survival 95%

Refer Appendix Two

Biological control research in country of

• rigin
• Paropsis charybdis is one of many

eucalyptus leaf beetles native to Australia

• Field work collaboration with Dr Geoff

Allen at the University of Tasmania

• Earlier research evaluated all the

parasitoids of P. charybdis

• Eadya (initially named paropsidis) most

promising to be host specific

• Molecular research confirmed host

range, and number of species.

• Since 2000 reared thousands of leaf

feeding caterpillars and 2700 Gonipterus larvae (weevils) reared – no Eadya

Results in Sharanowski et al. 2018

Eadya daenerys – larval parasitoid (Braconidae)

• Parasitoid that attacks larvae in

spring (first generation)

• Lays one egg directly into the

larva of any size

• Eats it from the inside out,

pushes out after 3 weeks

• Spins cocoon in soil
• Overwinters until emerges as an

adult following Nov-Dec

• Eadya only reared from 4

Paropsis and Paropsisterna beetles in Australia

Approx 10mm long

Photo: Anthony Rice Described in Ridenbaugh et al 2018

Scion assessed the risk this parasitoid might pose to other non-target beetles in NZ

• Pest paropsines are Chrysomelidae:

Chrysomelinae beetles

• New Zealand has no native paropsini beetles,
• nly invaded pests
• But NZ has other Chrysomelinae
• Most risk if medium sized (>5mm), with

leaf feeding larvae, active during early summer

• Prioritise beneficial species in either

subfamily Chrysomelinae or Galerucinae (weed agents)

• Utilised both traditional and a model

(PRONTI) to draw up the best host testing list

Phylogenetic relationships between target and non-targets

Chrysomelidae

Chrysomelinae Chrysomelini Paropsis charybdis Trachymela sloanei Dicranosterna semipunctata Phyllocharitini Allocharis tarsalis Chalcolampra speculifera Gonioctenini Chrysolina abchasica Gonioctena

• livacea

Galerucinae Galerucini Lochmaea suturalis Alticini Agasicles hygrophila Cassidinae Cassidini Cassida rubiginosa Criocerinae Neolema

• globlini

Exotic pests Largest endemic chrysomelines Beneficial weed BioControl Agents

• Eadya target is Paropsis charybdis the

largest of the invasive pest paropsines in NZ

• Phylogenetically closest relatives exotic

pests in NZ, subfamily Chrysomelinae: – tested 2 largest out of Paropsisterna spp., Trachymela spp. (paropsines), Dicranosterna, Peltoschema

• Endemic species in subfamily

Chrysomelinae - tested 1 we located –

• Allocharis. Also searched unsuccessfully

for Chalcolampra, & Caccomolpus.

Undertook host testing (Appendix 5)

Dicranosterna Trachymela Allocharis Paropsis

• Beneficial weed biocontrol agents in

subfamily Chrysomelinae – tested 2: Gonioctena olivacea on Scotch broom, and Chrysolina abchasica on Tutsan.

• Beneficial weed biocontrol agents in

sister subfamily Galerucinae – tested 2: Agasicles hygrophila on Alligator Weed, and Lochmaea suturalis on Heather

• Beneficial weed biocontrol agents in

unrelated subfamilies – tested 2: Neolema ogloblini on Tradescantia (Criocerinae), Cassida rubiginosa on Californian thistles (Cassidinae).

…host testing continued

Chrysolina Gonioctena Neolema Cassida Agasicles Lochmaea

Host testing methods in containment

• No-choice physiological assays – 24 hours one

female to 8 larvae on foliage, rearing and dissecting any dead larvae

• Close-up behavioural observations in petri dishes

Results of No-choice physiological host range :

• Viable parasitism – Paropsines only:
• Paropsis charybdis target pest 34+% (n=120)
• Trachymela sloanei 12.5% (n = 5 reps)
• Non-viable parasitism found only in

Chrysomelines, after larval dissections

• Dicranosterna semipunctata 1.6% (n= 16)
• Allocharis nr tarsalis 7.5% (n= 10)
• Chrysolina abchasica 1.8% (n=14)
• Gonioctena olivaceae 5.2 % (n=12)
• All other species in Galerucinae, Cassidinae and

Criocerinae, 0% parasitism (n=11 -16)

Paropsines Chrysomelines

Conclusion from physiological tests

• Non-target larval rearing survival in the laboratory ranged from 40%

(Chrysolina) to 90% (Allocharis). Generally was good.

• Target P. charybdis rearing survival dropped from 95% in the

absence of parasitism, to 9% after stinging by Eadya.

• Physiological host tests are considered worst case scenario, over-

estimating likely field host range, as long as appropriate life stages are presented, and parasitoids remain active and viable through-out the tests.

• Our tests ran for 24 hours, thereby allowing for nocturnal or diurnal

activity by the parasitoid, and long enough for deprivation effects to become extreme.

• Only paropsines tested, were complete physiological hosts

Body size comparisons among beetles

Predicted minimum host size

• 1/5 of the Eadya larvae emerging from T. sloanei became a minute

but viable adult, confirming minimum host size of about 35 mg

• Suggests the non-target beetles will be too small to be physiological

hosts, therefore unable to form populations, even if had been hosts.

Hosts Non- Hosts

Paropsines

Chrysomelines

Behavioural observations

• Often host testing of parasitoids only reports on results of

physiological host range

• But behavioural observations can assist with interpretation of any

uncertain data

• Therefore we report here the additional data on behaviour of

individual female parasitoids in two-choice, and no-choice sequential petri dish assays

• Non-parametric statistics (comparisons of medians)

• Attack rate (number stings per minute)

when given a CHOICE significantly less than against P. charybdis

Number of ovipositor-insertions per minute

• Attack rate (number stings per minute spent on the plant) when in a

NO Choice test (n=12-16 reps^)

^Only in 8 reps with Trachymela sloanei was there no sig difference in attack

Conclusion on risk to non-targets

• No non-target beetles feed on any NZ Myrtaceae
• Eadya parasitoids show little interest in non-target except

Trachymela and Paropsis that both feed on Eucalyptus leaves

• All beetles on Eucalyptus leaves in NZ are pests
• Some physiological effects (mortality) on sub-alpine native

beetle Allocharis attack from no-choice 24 hour assay, but larvae ignored in two-choice petri dish tests

• Cannot rule out that Eadya will reach sub-alpine areas,

but without presence of Eucalyptus or paropsine hosts, believe they will move on, not stay and unlikely to search non-Myrtaceous plant species.

Minimal Risk to Non-targets

Larger native beetle species have been collected from alpine peaks such as: Mt Arthur, Gordons Knob, Mt Cook village, Mt Earnslaw, Ben Lomond, Mt Dick, Arthur’s Pass, Old Man Range ( )

CLIMEX Composite Match Index for Eadya Tasmania

• cf. NZ
• minimal overlap

Introducing Eadya will significantly increase P. charybdis larval mortality

• This is what a sustainable eucalyptus

forest industry needs

> 90% survival ~ 9% survival

So benefits outweigh risks of introducing this parasitoid, Eadya daenerys

• Biocontrol is environmentally sustainable method of pest control
• Previous biocontrol agents have controlled the second generation of

the pest Eucalyptus tortoise beetle

• Eadya daenerys will reduce larval survival in first generation
• It is specific in Australia to some Paropsis and Paropsisterna

beetles (known as “paropsines”)

• Eadya daenerys could prevent $7.2 million in yield losses per year

from damage to susceptible Symphyomyrtus species

• Sustainable control will reduce spraying, better for environment
• Economic benefits outweigh any potential risks to air, soil, water,

testing reveals a very low risk to any non-target beetles

Acknowledgements

• Sustainable Farming Fund (MPI)
• Scion SSIF (core funding)
• NZ Farm Forestry Association: Dean Satchell
• Speciality Wood Products Partnership
• Southwood Exports Ltd: Graeme Manley
• Oji Fibre Solutions: Adam Mills, David Fox, Richard Sherratt
• Scion Forest Protection staff: incl. summer students, co-funded by University
• f Waikato
• Uni of Tasmania: Geoff Allen, Bek Smart, Vin Patel, Steve Quarrell, Karina

Potter

• Helen Nahrung and Owen Seeman
• TasForests, iFarm, PF Olsens for access to sites
• Forest Owners Association
• Landcare Research: Rich Leschen, Hugh Gourlay, Chris Winks, Paul

Peterson

• AgResearch: Mike Cripps

www.scionresearch.com

Scion is the trading name of the New Zealand Forest Research Institute Limited

Prosperity from trees Mai i te ngahere oranga