Snail Management and Research Updateg p

SARDI EntomologySARDI Entomology

Helen DeGraaf

Pest Facts SA & western Victoria Edition

• FREE electronic newsletter produced for growers and advisors on an as-needed basis throughout the winter seasonan as needed basis throughout the winter season

• Regular updates on invertebrate pest issuesRegular updates on invertebrate pest issues in broad acre crops

• Pest warnings, management information• A way to detect regional pest issues• A way to detect regional pest issues

early and highlight the need to check crops

• www sardi sa gov au/pestfacts• www.sardi.sa.gov.au/pestfacts• kym.perry@sa.gov.au• helen.degraaf@sa.gov.au

• (08) 8303 9370

The Battle Plan

• The Enemy • New weapons research

• The Battle Front

• Tactics

Biological warfare

Improving bait performance

• Biosecurity Novel approaches

The Advertiser, 26/9/12

The Enemy

Round:Round:

White Italian snailVineyard or common whiteTheba pisana

yCernuella virgata

C i lConical:

Small conical snailCochlicella barbara

Conical or pointed snailCochlicella acuta

The Enemy

And now 2 more pest species?

• Small brown citrus snail in grain from western Eyre P i lPeninsula

• Usually associated with citrus orchards

Small brown citrus snail

orchards

• Green snail established in Perth for 30+ years

• 2011 discovered in Victoria (Cobram area)

Green snail

The Enemy

Reproduction:

• Over-summer on elevated positions (pointed snails can over-summer under ground)• Autumn rains trigger activity• Autumn rains trigger activity• Feeding and maturing for 2 weeks mating laying eggs• Start of egg laying is determined by soil moisture

Hermaphrodites every snail can lay 400 eggs!• Hermaphrodites, every snail can lay 400 eggs!

To monitor for egg-laying:

• Look early in the morning• Snails on soil surface with foot inserted into topsoil• Eggs laid in clusters in shallow holes

• Hatching after 2 weeksg

The Battlefront

• 2010 and 2011 saw a major increase in snail activity, including early-season activity, densities and damagedensities and damage

• Primarily related to wetter (& cooler) summer/autumn conditionssummer/autumn conditions

• 2012 has seen residual high numbers and id bl l ti itconsiderable slug activity

• Longer-term farming system trends may be influencing snail impacts

The Casualties

• Major increase in baiting programs = higher $$ inputs

• Crop damage and yield lossp g y

• Harvest costs:some crops left unharvestedsome crops left unharvestedclogging damage, header

modificationgrain cleaning costsgrain cleaning costs

• Delivery rejection or grain value d ddowngrade

contamination, grain discolouration

Key Tactics

• Know your problem species and understand their behaviour (e g over-summering location)(e.g. over-summering location)

• Use an integrated approach The ‘silver bullet’ has yet to beUse an integrated approach. The silver bullet has yet to be discovered!

• Aim to reduce snail numbers prior to egg laying

• Monitor live snail density before and after treatments

• Reduce weeds over summer

• All year round consider opportunities to nail the snails!

War games - Bashing

• Cabling, rolling, slashing

• Cabling is best bet where surface stones exist (beware ironstone)

• Bashing is most effective when surface temp over 35°Cp

• Overnight moisture, summer weeds and heavy surface mulchweeds and heavy surface mulch reduce mortality

• Repeat treatments increase• Repeat treatments increase mortality

War games - Burning

• A slow, hot burn can be 80-90% ff ti d il

90

100

e of

effective on round snails

• Consider erosion risk & nutrient 50

60

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s pe

rcen

tage

opul

atio

n

loss

• Controlling summer weeds first 2030

40

50

live

snai

ls a

sin

itial

po Pre burn

Post burn

gsubstantially improves kill

• Protect burnt and snail free areas

0

10

Burning only Desiccation and burning

% l

Protect burnt and snail free areas from reinvasion

• Less effective against conical

and burning

(modified from Bash’em Burn’em Bait’em)

• Less effective against conical snails (shelter under rocks and below ground)

War games - Baiting

• Timing is critical to stop egg-laying

• Snails must be active; cool & moist conditions following application

• It’s OK to bait before rain

Populations >80/m2 will need multiple• Populations >80/m2 will need multiple applications and higher rate.

f• Remember to bait fencelines and scrub lines

• Kill summer and brassica weeds

• Finish baiting 8 weeks before harvestg

Snail management resources

Download copies from GRDC Media Centre Bookshop website

LOOK OUT FOR GREEN SNAIL(Cantareus apertus – formerly Helix aperta)

• Native to southern Europe and North AfricaEstablished in the Perth area (WA) in the 1980s– Established in the Perth area (WA) in the 1980s

– Found in Vic (Cobram area) in 2011.

• Description:p– whitish flesh with olive green shell (up to 25 mm shell

diameter

O d th th il f (15 150Juvenile green snail (top)• Over-summers underneath the soil surface (15-150 mm

depth)

Wid h t

snail (top) Common garden snail (bottom)

• Wide host range: – wheat, lupins, pasture grasses, fodder (hay),beans, peas,

vegetable crops (e.g. cabbage, cauliflower, lettuce) and native plantsnative plants

• If you suspect you have found green snail, please contact Biosecurity SA or call your Exotic Pest Hotline immediately on 1800 084 881

Photos courtesy Dept of Primary Industries, Victoria.

1800 084 881

Key biosecurity practises around movement and hygiene include:include:

1. Restrict movement of machinery, equipment and produce (e.g. hay- bales) from entering property until inspectedfrom entering property until inspected

This will help to reduce the risk of bringing more snails onto property

2. Clean all machinery and equipment to dislodge snails before moving • Use high pressure cleaning • have a designated clean down facility / area

3 Erect a farm gate biosecurity sign3. Erect a farm gate biosecurity sign• demonstrates your commitment to cleanliness and safety

Ensures visitors contact you before entering any paddocks where there is a greater risk of spreading pestsgreater risk of spreading pests

Photos courtesy ; PIRSA,  M. Richards, SARDI Entomology  and DPI Vic.

More information on green snail: ghttp://www.pir.sa.gov.au/biosecuritysa/planthealth/emergency_plant_pests/green_snails

For a ‘free’ biosecurity farm gate sign contact:J d B ll tiJudy BellatiSouth Australian Grains Biosecurity Officer

(08) 8207 7843 0412 218 228(08) 8207 7843 or 0412 218 228judy.bellati@sa.gov.au

New weapons research

Biological warfare:Biological warfare:- Nematodes

Improving bait performance:

Novel approaches:- PERLKA® fertiliserImproving bait performance:

- Juveniles- Bait size

- Low biuret urea- Caffeine

Biological warfare

• Nematodes in association with specific bacterial isolates have proven effective in killing snails in laboratory trials – Charles Sturt Universityeffective in killing snails in laboratory trials Charles Sturt University

• Nematodes enter the snail gut where they release lethal bacteria which kill the snailwhich kill the snail

• The nematode then feeds and breeds within the rotting snail

Biological warfare

• Pathogenicity testing to find most lethal combinations of nematode and bacterial isolates

• In laboratory conditions, some combinations cause 100% mortality in all 4 snail species within 8 daysp y

• Field conditions do not generally favour nematode survivallow humiditylow humiditysoil typeUV raystemperaturetemperature

• High volumes of water are required at applicationat application

Biological warfare

• The 1st SA field trial was in Sept 2011 in a lentil crop, Warooka. • Treatments were:

Bait (registered rate)Low and high rate of nematodes (4,500 L / ha)Untreated controlUntreated control

• Assessed live conical and white snails on (i) ground and (ii) lentil plants at four post-treatment dates (7, 13, 28 and 34 DAT)

• For one of these assessments (live conical snails on ground at 13 DAT) there was a significant nematode treatment effect

70

40

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ve s

nails

a

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Num

ber o

f liv

bbb

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Control Bait Nematode Low

Nematode High

N

Biological warfare

Experiment 1: May 2012, Warooka

• Promising nematode/bacteria combination applied at 900L/ha (nematodes diluted in water)

% Mortality Round snails Conical snailsControl 7.0 9.5Bait (Meta) 94.7 91.0Nematode 5.5 20.1

• Very disappointing results may be due to:incompatibilityincompatibilityenvironmental conditionsformulation problemstransport and shippingtransport and shipping

Biological warfare

Experiment 2: September 2012, Warooka

• 2 potential nematode/bacteria combinations applied at 4,500L/ha (nematodes diluted in water)

% Mortality Round snails Conical snailsBait (Meta) 83.3 77.9( )Nematode 1 15.4 44.7Nematode 2 15.9 12.6

• Problems that need to be overcome:desiccation (improve formulation)desiccation (improve formulation)application method (too much water)

Baiting research - Juveniles

Baits only kill adults snails?

• Comparing bait products and mortality of juveniles (all 4 species)

• Experiments took place at Roseworthy under field conditions in August 2012

• Juveniles (

Baiting research - Juveniles

• 60% mortality of common white juveniles

• Pointed snail mortality may have been inflated due to limited dead plant material (f d h t) i

100

(favoured host) in arenas

A t lit b t j il

70

80

90

100 Average mortality between juvenile snail species (all baits combined)

Arenas contained:

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50

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mor

talit

y • brome grass• stinging nettle• canola

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20

30

0

%

0White Italian Common white Small pointed Pointed

Baiting research - Juveniles

90

100Bait effects on juvenile snail mortality (all 4 species combined), n = 5   

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70

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talit

y

20

30

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50

% m

ort

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Meta Slugger Slug Out Slug Off Metarex Multiguard Mesurol

A. I. 15g/kg met’hyde

15g/kg met’hyde

18g/kg met’hyde

30g/kg met’hyde

50g/kg met’hyde

60g/kg iron chelate

20g/kgmethiocarb

A. I. ( / 2)

9.4 13.2 16.9 9.5 32.2 76.4 12.2(mg/m2)# baits 4 4 16 6 8 6 4

Baiting research - bait size

• Variable mortality between treatments may be a reflection of bait size (i.e. how many pieces on the ground – frequency of interception)

• Field arenas were set up to test the effects of bait size and rate on snail mortalityy

• Results are yet to be compiled, trials underway on slugs in Vic.

Novel approaches – PERLKA®

• Granulated calcium cyanamide

• Used as fertiliser (nitrate) in horticulture, mostly Europe

• Described as a “multi-functional fertiliser”

Claimed to have fungicidal herbicidal and• Claimed to have fungicidal, herbicidal and insecticidal properties

Al l i d b i il ( ll ) d• Also claimed to be toxic to snails (all ages) and snail eggs

• GRDC funded trial

SARDI conducted 2 experiments:pEgg mortality lab trial2 large scale field trials

Novel approaches – PERLKA®

• White Italian snail eggs were collected at Warooka, Yorke P.• 45 eggs per dish• Light rainfall event simulated every 2-3 days• Hatchlings were recorded for 34 days

Soil surface with PERLKA® granules

Stocking material over container g

Cluster of snail eggs Drainage hole

Treatment Percent eggs hatched ± SE (Actual)Control 25.0 ± 7.72 (11.25 ± 3.47)

/

4 dishes per treatment

200kg/ha 0 (0)400kg/ha 0 (0)600kg/ha 0 (0)800kg/ha 0 (0)

Novel approaches – PERLKA®

• Canola and pasture field trials at Warooka.C l t 6 l f t t f b /t i it• Canola at 6-leaf stage to recover from burn/toxicity

• Control vs 250kg/ha (recommended rate)40m

PERLKA 40mPERLKA

PERLKA PERLKAPERLKA

P t t t il t 5 d t (50 50 ) l t• Pre-treatment snail counts, 5 quadrats (50cm x 50cm) per plot• Post-treatment snail counts at 9 weeks, 5 quadrats per plot

Novel approaches – PERLKA®

Results• Juvenile snails accounted for majority of snails pre and post treatment.

• Majority of snails were the White Italian and Pointed snails j y

Average number of juvenile snails (all species) per 2500cm2 (¼ m2)

Canola PasturePre-treat Post-treat % change Pre-treat Post-treat % change

Control 38.2 a 178.8 a ↑ 468% 497.4 a 634.6 a ↑ 128%PERLKA® 28.2 a 113.4 a ↑ 402% 333.0 a 471.2 b ↑ 142%

Tukey’s test y

• Results are less than impressive, but may reflect patchiness in field.

Novel approaches – Low Biuret Urea

L b t il t t i l h d i• Laboratory pilot trials showed promise

• Field trial set up at Warooka, YP to test toxicity effects of Low Biuret Urea on snails

• Replicated plot design in a wheat, each plot p p g , p30x30m

• TreatmentsTreatmentsUrea 10kg/ha (applied in solution 50L/ha) Urea 20kg/ha (applied in solution 50L/ha)Water only (50L/ha)Water only (50L/ha)

• Post treatment assessments occurred this week

Novel approaches - Caffeine

• Synthetic caffeine solution to kill/repel y psnails away from crops at harvest time

• Trials planned in peas and windrowedTrials planned in peas and windrowed canola

• Pure synthetic caffeine is dissolved in• Pure synthetic caffeine is dissolved in water with sodium benzoate to improve solubility

• Residue analysis in harvested product

• Registration hurdles

Acknowledgements

SARDI:Greg BakergLatif SalehiSarah MantelMark BarrettMark BarrettKym Perry

Graham Hayes (farmer Warooka)Graham Hayes (farmer, Warooka)

Charles Sturt University:P f G i A hProf. Gavin Ash Dr Aisuo Wang

Michael Richards (NRM)

GRDC & Southern panel membersp

Grain Pest Resistance Project

• cesar at The University of Melbourne

• Aim to build a database of chemical resistance in crop pest species Australia p p pwide – Early warning system

• Focus on earth mites and aphids and• Focus on earth mites and aphids, and bioassay to determine levels of resistance

C ll t t ti l ti• Collect representative populations throughout the states

• Respond to all incidences of resistance for all mite and aphid pests

Grain Pest Resistance Project

If you suspect a chemical failure for any mites or aphids in any crop, l l t k !please let us know!

cesar can arrange a FREE resistance test and provide assistance withcesar can arrange a FREE resistance test and provide assistance with recommendations for control.

Helen DeGraafHelen DeGraaf SARDI Entomology8303 9543helen.degraaf@sa.gov.au

Remember....

• Know your problem species and understand their behaviour (e.g. over-summering location)(e.g. over summering location)

• Use an integrated approach. The ‘silver bullet’ has yet to be g pp ydiscovered!

• Aim to reduce snail numbers prior to egg laying

• Monitor live snail density before and after treatments

R d d• Reduce weeds over summer

All d id t iti t il th il !• All year round consider opportunities to nail the snails!