Gastropods = Slugs + Snails

Slug and snail pests in urban areas and the development of novel tools for their management

Rory Mc Donnell

DepartmentGastropods of Crop and Soil =Science, Slugs Oregon + Snails State University, Corvallis Our relationship with slugs and snails Traditionally a repulsive organism

. Slug phobias – American Journal of Clinical Hypnosis Shell-less snails! Slug = snail minus an external shell!

Advantages of no shell: – Squeeze through very tight spaces – Live in environments that snails cannot – Move more quickly i.e. top speed 0.025mph! Slug Body Plan

Keel Ocular tentacles Pneumostome Mantle

Aydin Orstan

Sensory tentacles

Caudal mucus pore Tubercle Slugs and snails as pests . Direct pests of agriculture, suburban, urban, natural areas, and interface of these systems

Purdue Extension Choke disease – Jay Pscheidt

. Vector human pathogens – e.g. Escherichia coli

. Aesthetic damage e.g. mucus and faeces Pest species in Oregon What species are causing the damage? Invasive slugs and snails Predominantly from Europe European Brown Garden Snail - Helix aspersa

Josua Vlach, ODA White-soled Slug - Arion circumscriptus

Roy Anderson - MolluscIreland Future threats

What species should we be worried about showing up here in the future? Cuban Slug - Veronicella cubensis

Cuban Slug Should Oregon be concerned? Collected on the mainland in 2006

Angiostrongylus cantonensis Potentially fatal in humans Giant African Snail - Lissachatina fulica

Robert Pearce Giant African Snail Giant African Snail

James Smith and Glenn Fowler – USDA APHIS PPQ CPHST Urban Infestation in Miami 1966 infestation in Miami – Seven years – 18,000 snails – $1 million New infestation – 8 September 2011 Miami Infestation Miami Dade Co.

22 cores

35 miles

>133,000 snails

$7.8 million

~$60 per snail Miami Infestation

Why have there been two invasions in Miami, Florida?

Snail mucus is drank during voodoo rituals and is believed to have healing properties Miami Infestation - Eradication

1. Hand collecting

2. Trapping

Joe Raedle Getty Images 3. Molluscicides

4. Sniffer dog Miami Infestation - Eradication

Snail blog Look for it! Report it! Bus and billboard signs Radio and newpapers Television and cinema Home interviews Control options for slugs and snails

Chemical molluscicides – Metaldehyde e.g. Slug-Fest®, Metarex – Iron Phosphate e.g. Sluggo® – Chelated Iron e.g. Slug Kill® – Methiocarb e.g. Mesurol 75-W® FallBrookFertilizer.com Tillage

Handpicking Traps Barriers e.g. copper © mopatin New approaches to control

Development of attractants

Plant extracts as molluscicides

Biological control using Novel attractants natural enemies

Forestryimages.org Biological control using nematodes Biological control using insects Novel attractants

James Smith and Glenn Fowler (USDA-APHIS-PPQ-CPHST) Novel attractants Novel attractants

Asian semi-slug

Site 1 Site 2 Food Extract Water Food Extract Water Giant African Snail 200 109 53 26 Asian semi-slug 133 72 103 53

The mean number of collected Giant African Snails and Asian semi slugs was significant greater (P<0.05) in the food extract versus water plots Novel attractants

Extract appeared to increase bait efficacy Potential for point source applications of attractant and molluscicides

Decreased molluscicide use Decreased non-target effects Increased bait efficacy Novel attractants What about novel attractants for other species?

Gray field slug European Brown Garden Snail

Highly attractive food source identified for both species in late 2016 Plant extracts as molluscicides

. Essential oils used against plant nursery pests such as aphids and weevils

. Little research with snails and slugs

. Bitter Orange, Cedarwood, Cinnamon, Clove, Eucalyptus, Garlic, Lemongrass, Peppermint, Pine, Rosemary & Spearmint

Helix aspersa Essential oils

. LC50 calculated using probit analysis

. Marker to compare the toxicity of oils Essential oils Essential oil LC50 Clove 0.027% Pine 0.082% Spearmint 0.103% Decreasing toxicity to Garlic 0.115% European brown garden Peppermint 0.140% snail eggs and juveniles Cinnamon 0.157% Lemongrass 0.160% Mc Donnell et al. (2016) Journal of Pest Science

. Clove was significantly (P<0.05) more toxic than all other oils

. Also more toxic than Snail and Slug Away® Essential oils . Clove oil was toxic to the eggs and juvenile snails but is it also phytotoxic?

. Potted Plant Trials • Hosta ‘Royal Standard’ • 5% clove oil (+ control) • Test solution (0.116%) • Water (- control)

. Each treatment replicated 10 times Essential oils . Positive control: 100% of test leaves (n=10) on all plants with symptoms of phytotoxicity . Negative control and test concentration: 0% of test leaves (n=10) on all plants with symptoms of phytotoxicity

Positive control (3 days)

Negative control (14 days) Test concentration (14 days) Essential oils

Percentage mortality of Helix aspersa eggs (n=10) and juveniles (n=10) in potted plant bioassays drenched with a positive control (5% clove oil), negative control (water) and test solution.

Immature stage Positive control Test solution Water control Juveniles (after 1 day) 100% 100% 0% Eggs (after 30 days) 100% 100% 0% Advantages of clove oil

. Rapid mortality (<24hrs)

. Constituents do not persist in water or in the soil

. Pleasant smelling and harmless to humans

. Exempt from pesticide registration requirements under Sect. 25(b) of the Federal Insecticide, Fungicide, and Rodenticide Act. Essential oils

Potential for use in Oregon?

Pre-shipping treatment for potted plants

Hot washes for commodities such as Christmas trees

Hot spot areas in infested sites where slugs and snail congregate Biological Control

Use of natural enemies to suppress a pest populations

Under researched for gastropods eventhough: – Diverse fauna of natural enemies – Biocontrol agent is available in Europe Biological Control

. Nematode: Phasmarhabditis hermaphrodita

. Lethal to pest slugs and some snails

. 12 million infective juveniles in clay

. Easy to apply

. Gastropod specific

. 89% reduction in damage to winter wheat

. >95% reduction in orchid damage Biological Control Not currently available in North America 

2,522 specimens 11 slug species 5 snail species

geology.com Nematodes 700 dead slugs and snails >40% had associated nematodes Phasmarhabditis hermaphrodita

How infectiveGiant is African the Snail US strain of the nematode?

Roy Anderson - MolluscIreland

FLICKR - Shadowshador

European Brown Garden Snail Valencia Slug Paul De Ley – UC Riverside Nematodes

Malacopathogenic nematodes could be an important tool for managing slugs and snails in Oregon

Preliminary screening has identified parasitic nematode species in the state (Ross et al. 2010)

Climate conditions should facilitate biological control

Demonstrated efficacy in Europe for urban gardens Alloionema appendiculatum – Irma Tandingan De Ley and vulnerable crops. Snail and slug-killing flies

Patrik Katona . Shade flies, also called sciomyzids . Maggots feed on slugs and snails . Reduction in pest slug population if flies are present? . ~50 species known from Oregon

Bugnet Predaceous ground beetles

. Major predators of slugs

.Beetle banks - Raised native grass mounds

LePotager.com . Safe overwintering = spring predation

. Successful experimental trials in UK and New Zealand

. Oregon beetle banks! Beetle Bank in Oregon - Gwendolyn Ellen Conclusions

No quick fix or a single silver bullet for slug and snail control

Must develop novel tools

An Integrated Pest Management (IPM) approach will be key Additional Information on Slugs and Snails

Website on gastropods in Oregon nurseries (Robin Rosetta): http://oregonstate.edu/dept/nurspest/mollusks.htm

Slug Portal (Amy Dreves): http://agsci.oregonstate.edu/slug-portal Acknowledgements US Department of Agriculture Western Region IPM Center California Department of Food and Agriculture

David Yoo Sarinah Simmons Robin Veasey Any questions!

E-mail: [email protected]

Twitter: @RoryJMcDonnell