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Gastropod attractants: Potential management tool for Giant African Land Snail Lissachatina fulica? RESEARCH UPDATE Rory McDonnell 1, Amy Roda 2 and Jocelyn.

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Presentation on theme: "Gastropod attractants: Potential management tool for Giant African Land Snail Lissachatina fulica? RESEARCH UPDATE Rory McDonnell 1, Amy Roda 2 and Jocelyn."— Presentation transcript:

1 Gastropod attractants: Potential management tool for Giant African Land Snail Lissachatina fulica? RESEARCH UPDATE Rory McDonnell 1, Amy Roda 2 and Jocelyn Millar 1 1: Department of Entomology, University of California, Riverside 2: CPHST, USDA-APHIS, Subtropical Horticultural Research Station, Miami

2 Background Chemical cues play roles in feeding, prey detection, predator avoidance, alarm responses, species recognition & reproduction in gastropods External attractants e.g. from food sources Possible pheromones –Sex pheromones –Aggregation pheromones

3 Sex pheromones Photo: Wikimedia Commons Spawning and breeding in mud snails organized by at least two kairomones and three pheromones Gland in the head produces a pheromone that elicits courtship and copulation Gland in the head produces a pheromone that elicits courtship and copulation Ilyanassa obsoletaEuhadra peliompha exoticsguide.org

4 Aggregation Pheromones Lissachatina oriented towards odor of conspecifics Source reported to be the pedal mucus gland Attractant is a pheromone Source: Chase (1978) Source: Chase (1978)

5 Why no further work to follow up?

6 Our Approach 1. Attractants produced by conspecifics Follow up on preliminary work by Chase from 1978, showing attraction of GAS to odors from conspecifics Follow up on preliminary work by Chase from 1978, showing attraction of GAS to odors from conspecifics 2. Attractants from other sources Identify and develop attractants from other sources (e.g., food) Identify and develop attractants from other sources (e.g., food)

7 1. Pheromones

8 Response of Lissachatina fulica to the odor of conspecifics X 2 = 24.69, P<0.001, n=20

9 Aeration chamber for collecting odors from live snails

10 Odor analysis results Little difference between snail and control aerations One compound appeared consistently in snail odor collections 2-diethylaminoethanol

11 Response of Lissachatina fulica to a 0.01% solution of 2-diethlyaminoethanol X 2 = 6.14, P<0.05, n = 14

12 2. Other attractants Fed snails a variety of different foods With one food item, noticed a distinct oriented mass movement towards the food Much more pronounced than normal, clearly strong attraction to odors from the food

13 Attraction to food odors Pronounced oriented movement towards food source

14 Replicated bioassays Two choice bioassay 1ml of treatment and 1ml control on filter paper Position of treatment and control switched after each replicate Snails tested individually to prevent trail-following Choice made when snail touched the Petri dish or after 45min Treatment Control

15 Response to steam distillate X 2 = 6.07, P<0.05, n = 10 Statistically significant attraction Result: Attractants are extractable and heat stable

16 Response to ether extract of steam distillate X 2 = 6.07, P<0.05, n = 10 Statistically significant attraction Result: Attractant extractable into organic solvent, easier to work with

17 Response to acid-treated steam distillate X 2 =6.00, P<0.05, n = 10 Statistically significant attraction Result: Attractant cannot be amine or other organic base

18 Response to base-treated steam distillate X 2 = 7.00, P<0.05, n = 10 Statistically significant attraction Result: Attractant cannot be organic acid

19 Response to neutralized ether extract of steam distillate X 2 = 20.20, P<0.001, n = 10 Statistically significant attraction Result: Attractant is one or more neutral compounds in the steam distillate

20 Response to methanol elution of steam distillate volatiles trapped on solid phase extraction cartridge X 2 = 8.32, P<0.05, n = 10 Statistically significant attraction Result: Attractant is a moderately polar compound

21 Conclusion The attractant is a heat-stable neutral compound(s) that is moderately polar Some attraction to a partial reconstruction of the compounds in the neutrals fraction

22 Next steps! Pheromone: 1. Continue to analyze the aeration extracts 2. Testing of pedal mucus gland

23 Next steps! Food based attractant: 1. Analysis of the neutrals fraction from the steam distillate 2. Development of a fractionation scheme 3. Reconstruction of the volatiles blend for bioassays

24 Questions? Acknowledgements: APHIS-PPQ-CPHST for funding to date APHIS-PPQ-CPHST for funding to date


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