Gastropod attractants: Potential
management tool for
Giant African Land Snail Lissachatina fulica?
RESEARCH UPDATE
Rory McDonnell1, Amy Roda2 and Jocelyn Millar1
1: Department of Entomology, University of California, Riverside
2: CPHST, USDA-APHIS, Subtropical Horticultural Research Station, Miami
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
Sex pheromones
Ilyanassa obsoleta
Euhadra peliompha
exoticsguide.org
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
Aggregation Pheromones
Lissachatina oriented towards odor of conspecifics
Source reported to be the pedal mucus gland
Attractant is a pheromone
Source: Chase (1978)
Why no further work to follow up?
Our Approach
1. Attractants produced by 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)
1. Pheromones
Response of Lissachatina fulica to the odor of
conspecifics
22%
Treatment Arm
Control Arm
78%
X2 = 24.69, P<0.001, n=20
Aeration chamber for collecting
odors from live snails
Odor analysis results
Little difference between snail and control
aerations
One compound appeared consistently in
snail odor collections
2-diethylaminoethanol
Response of Lissachatina fulica to a 0.01%
solution of 2-diethlyaminoethanol
22%
14%
64%
X2 = 6.14, P<0.05, n = 14
Treatment Arm
Control Arm
No Choice
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
Attraction to food odors
• Pronounced oriented movement towards food source
Replicated bioassays
Treatment
• 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
Control
Response to steam distillate
20%
10%
Steam distillate
70%
Control (water)
No Choice
X2 = 6.07, P<0.05, n = 10
Statistically significant attraction
Result: Attractants are extractable and heat stable
Response to ether extract of steam distillate
10%
20%
Ether extract
70%
Control (ether)
No Choice
X2 = 6.07, P<0.05, n = 10
Statistically significant attraction
Result: Attractant extractable into organic
solvent, easier to work with
Response to acid-treated steam distillate
33%
67%
Acid-treated
Control (water)
No Choice
X2 =6.00, P<0.05, n = 10
Statistically significant attraction
Result: Attractant cannot be amine or
other organic base
Response to base-treated steam distillate
17%
Base-treated
Control (water)
83%
No Choice
X2 = 7.00, P<0.05, n = 10
Statistically significant attraction
Result: Attractant cannot be organic acid
Response to neutralized ether extract of steam distillate
Neutralised extract
Control (ether)
100%
No Choice
X2 = 20.20, P<0.001, n = 10
Statistically significant attraction
Result: Attractant is one or more neutral
compounds in the steam distillate
Response to methanol elution of steam distillate volatiles
trapped on solid phase extraction cartridge
25%
Neutralised extract
75%
Control
No Choice
X2 = 8.32, P<0.05, n = 10
Statistically significant attraction
Result: Attractant is a moderately polar
compound
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
Next steps!
Pheromone:
1. Continue to analyze the aeration extracts
2. Testing of pedal mucus gland
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
Questions?
Acknowledgements:
 APHIS-PPQ-CPHST for funding to date