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Colin H. Kyle, James P. McDonough and Romi L. Burks,

Location, Location, Location: Laboratory Experiment Shows Invasive P. insularum Choose Elephant Ear as Oviposition Sites. Colin H. Kyle, James P. McDonough and Romi L. Burks, Biology Department, Southwestern University, Georgetown, TX. Process of Invasion. Transported to New Area. Exotic.

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Colin H. Kyle, James P. McDonough and Romi L. Burks,

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  1. Location, Location, Location: Laboratory Experiment Shows Invasive P. insularum Choose Elephant Ear as Oviposition Sites Colin H. Kyle, James P. McDonough and Romi L. Burks, Biology Department, Southwestern University, Georgetown, TX.

  2. Process of Invasion Transported to New Area Exotic Establish Reproducing Population Invasive Spread to other areas Ecological Impact Adapted from Sakai et al. 2001

  3. Exotic Invasive Species:Global Threat on Many Fronts Biological • Compete with native species • Reduce native biodiversity Economic • EIS cost $120B in US alone – Pimentel et al. 2005 • $9B on aquatic EIS Political • Legal issues about regulations Social • Harmful to humans • Cost taxpayer money to control

  4. Focus: Pomacea insularum • Closely related to P. canaliculata • Large size • Voracious consumer • High fecundity • Native to temperate S. America • Established in bayous of Houston • Threatens Gulf Coast ecosystems (FL, GA)

  5. What to do about the snails? Introduced through the aquarium industry Transported to New Area Establish Reproducing Population P. insularum Currently • Long Term Implications • of Research • Prevent Spread • Limit Ecological Impact Spread to other areas Ecological Impact

  6. The Source of the Problem • Limit reproduction – control population growth • Each clutch contains up to 4500 eggs (mean = 2064 eggs) • Clutches hatch in 14 – 21 days • Removing egg clutches before they can hatch • Simple and undamaging to the environment

  7. Finding the Eggs • Determine where the snails will most likely oviposit • Understand egg laying (oviposition) behavior and activity

  8. Research Questions 1. Does P. insularum show preferences for the type of surface on which they lay eggs? 2. What behavior does P. insularum exhibit when reproducing?

  9. Question 1 Methods • Presented snails with 4 different surface types on which to oviposit • Elephant Ear stalk • Wood • Metal • Astroturf • Astroturf possible control mechanism • Poles of 1.9 cm diameter • Recorded the number of clutches laid on each surface type Elephant ear (Colocasia esculenta)

  10. Question 1 Methods • Constructed a tank system to contain snails for experiment • 12 microenvironments, each containing 2 female snails and 1 male • Deterred snails from ovipositing on the tank walls using water • Maintained for approximately 3 weeks • Analyzed preference using a Chi-Squared test

  11. Microhabitat

  12. Question 1 Results • Significantly more clutches laid on elephant ear (chi-square, p<0.01) compared to other substrates. • No clutches occurred on metal and Astroturf structures

  13. Question 2 Methods • Recorded location of each snail 3 times a day • Floor • Pole • Lettuce • Box • Wall • Grouped different pole and box types • Analyzed results using a Chi-Squared test Floor Pole Wall Lettuce Box

  14. Question 2 Results • Significant difference in percentage of time spent by snails on different locations within the tanks (chi-square, p<0.001). • Snails observed most either feeding on the lettuce or hanging onto the sides of the tanks.

  15. Females preferred to lay their clutches on the elephant ear more than on any other structure. The use of Astroturf or metal as control mechanisms in nature would be ineffective. Snails observed significantly more either on the walls of the tank or feeding on lettuce Suggests that snails spend most time feeding and searching banks for potential egg-laying surfaces than resting on the floor or boxes. Discussion of Results

  16. Results Mimic Field Observations • Most clutches in field observed on elephant ear plants. • Snails found in the field at the base of elephant ear stalks.

  17. Transported to New Area Establish Reproducing Population Spread to other areas Ecological Impact Conclusion • We now understand that P. insularum egg clutches will more likely be found in stands of elephant ear than any other structure around their habitat. • In future P. insularum invasions, removing egg clutches from plants near the banks should be an effective way of slowing their population growth.

  18. Acknowledgements • Texas Academy of Science • Southwestern University (Funding) • Dr. Burks (Advisor) • Mark Kramer and George Regmond (Armand Bayou) • James McDonough (Research Partner) • Sarah Hensley (Current Research Student) • Matt Barnes (Former Research Student) • Abby Youens (Former Research Student) • Brandon Boland (Former Research Student)

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