Are coastal populations of fire ants, Solenopsis invicta, preying

or scavenging on sea turtle nests?

Jaeson Clayborn

Impacts in Florida (and the rest of the U. S.)

� Thrive in human-altered environments

� Reduce native arthropod communities

� Detrimental to slow-moving (vulnerable) animals

� Consume eggs and hatchlings of various species

� Some people are seriously allergic to their venom

The good

And the ugly

The bad

Not so good

Nesting Behavior of Caretta caretta

• Demonstrate high nesting site fidelity

• Females do not provide maternal care

• Incubation period is about two months

• Few hatchlings per nest survive to adulthood

http://research.myfwc.com/images/articles

Manasota Key

• Moderately developed

• Caretta caretta (mainly) and Chelonia mydas nesting sites

• Moderately high number of Caretta caretta nests

Maps provided by the Florida Department of Environmental Protection Agency, Map Data ©2009 Google Maps.

Fort DesotoBoyd Hill

Research Objectives (Questions)

• Determine where ants are most abundant on the beach and which ant

is more prevalent

• Explore whether Solenopsis invicta actively hunts for eggs in

underground nests

• Analyze Caretta caretta nest data to assess the actual threat of

Solenopsis invicta in relation to other nest predators

• Justify whether chemical control does more harm than good

Hypothesis

Bait trap experiment:

The abundance of Solenopsis invicta should be higher in the vegetative zone.

Ho: There is no difference in the abundance of Solenopsis invicta in the vegetative zone versus

the non-vegetative zone.

HA: Solenopsis invicta are more abundant in the vegetative zone.

Buried egg experiment:

Solenopsis invicta will not locate buried eggs underground.

Ho: Solenopsis invicta randomly locates sea turtles eggs underground (get lucky).

HA: Solenopsis invicta intentionally locate and consume sea turtle eggs in underground nests.

Analysis of Caretta caretta data from Manasota Key (2004-2009)

Solenopsis invicta is a minimal threat to Caretta caretta nests.

HO: Solenopsis invicta is a not a threat to Caretta caretta nests.

HA: Solenopsis invicta is a threat to Caretta caretta nests.

Bait Trap Experiment: Materials and Methods

Results

Rsquare 0.12548

Adj Rsquare 0.118293

Root Mean Square Error 49.16083

Mean of Response 32.10027

Observations (or Sum Wgts) 369

One way Analysis of # of Ants By Part of beach

(Beach minus Raymond James)

Level Number Mean Std Error Lower 95% Upper 95%Low 120 9.2167 4.4877 0.392 18.042

Mid 123 31.4959 4.4327 22.779 40.213

Toe 41 57.5122 7.6776 42.414 72.610

Veg 85 53.0235 5.3322 42.538 63.509

Level Count Score Sum Score Mean (Mean-Mean0)/Std0

Low 120 15334.0 127.783 -7.435

Mid 123 24070.0 195.691 1.415

Toe 41 10174.5 248.159 4.179

Veg 85 18686.5 219.841 3.567

Wilcoxon / Kruskal-Wallis Tests (Rank Sums)

Level Count ProbA. lamellidens 1 0.00352B. obscurior 8 0.02817C. floridanus 2 0.00704Cremagastor sp? 1 0.00352D. bureni 65 0.22887F. pruinosus 18 0.06338P. bourbonica 1 0.00352S. invicta 176 0.61972T. simillimum 3 0.01056Unidentified 9 0.03169Total 284 1.00000

Does surface foraging correlate with subterranean foraging?

Sand

Beach Surface

Sea turtle nest

Fire ant interactions with sea turtle nests???

Surf Zone

High Tide Line

Toe Line

Sea turtle nest

Fire ant nest

Foraging tunnel 11

Buried Egg Experiment: Material and Methods

Results

N Y Total

Boyd Hill %

2571.43

1028.57

35

Ft. Desoto%

4794.00

36.00

50

Total (Both sites)%

7284.71

1315.29

85

Comparing the two sites, there was a significant

difference in predation (Pearson: ChiSq = 8.097;

p = 0.004)

DF = 1 R2 = 0.1120

Mystery

mammal

No

predation

S. invicta

S. invicta +

B. obscurior

Boyd Hill

Fort Desoto

Level Count ProbMystery mammal 2 0.057No predation 23 0.657S. invicta 8 0.229S. invicta + B. obscurior 2 0.057

Total 35 1.000

Level Count Prob

Mystery mammal 5 0.100

No predation 42 0.840

S. invicta 3 0.060

Total 50 1.000

Sea turtle nest predators at Manasota Key

Other threats

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Loggerhead nest data analysis (2004-2009)

Level Count Prob

Armadillo 27 0.04485

Bobcat 3 0.00498

Canine 75 0.12458

Coon 44 0.07309

Crow 1 0.00166

Fire Ants(Direct) 6 0.00997

Fire Ants(Indirect) 8 0.01329

Ghost Crab 10 0.01661

No Predation 417 0.69269

UNK 11 0.01827

Total 602 1.00000

Pest Management

• Tedious and time consuming

• Proper identification of ants and mounds?

• More environmentally friendly

• Safer

• Can harm and eliminate non-target organisms

• Can spread from target zones

• Expensive

• Less effort

Individual mound treatment Broadcast treatment

Photo by John Young

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Pesticides (Fire Ant Wars)

• Kills through ingestion

• Safer for the environment

• Relatively nontoxic to aquatic organisms, honeybees, and birds

� Kills upon contact

� Highly/very highly toxic to aquatic

organisms, honeybees, and birds (

bioaccumulates in aquatic organisms)

� Kills through ingestion

� Nontoxic to honeybees, birds, and

mammals

� Moderate/highly toxic to aquatic

organisms

Fipronil (The worst on this slide)

Boric Acid (The safest)

Carbaryl

Hydramethylnon (Amdro)

� Kills upon contact

� Highly toxic to honey bees, aquatic

invertebrates, some fish

Mark Heine

What pesticides can do (mainly broadcasting)

Fire antsFire ants

Fire ants

Other ants

Other antsOther ants

Broadcast baits

Habitat before pesticide application Ants are eliminated

Habitat after pesticide application

Argentine Ant

D. bureni

Forelius p.

Ants that look similar to D. bureni

Dorymyrmex bureni

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More ants at the beach (Where is the fire ant)?

Crazy Ant

FL Carpenter Ant

Tetra sim.

Fire Ant

Brachymyrmex obscurior

Harvester ant

Compact Carpenter Ant

1

2

3

45

6

78

20

Conclusion

Photos taken by John Young

• The number of foraging ants was significantly higher at the toe line and

vegetative area compared to the rest of the beach.

• A small percent (6%) of chicken eggs were consumed by Solenopsis invicta at

the beach.

• Predation by Solenopsis invicta was highest (12 %) at the control site.

• Data documenting Caretta caretta nest predation showed Canis latrans

predated the largest number of sea turtle nests, while Solenopsis invicta

accounted for 2%.

• The data suggests fire ants are not a threat to sea turtle nests.

• Pest management should steer away from chemical control on the beach

21

Confounding Factors

Bait Trap Experiment:

• Collection time allowed

• Placement of transects

Buried Egg Experiment:

• Proper amount of time left underground

• Humans and other animals

Analysis of Caretta caretta data:

• Variation in sampling over the years

• Misidentification of ants

Dorymyrmex bureni

Solenopsis invicta

Dorymyrmrx bureni 22

So what happens next?

� Are fire ants an actual threat or misunderstood?

� If yes, what measures should be taken to control them?

� Biological control?

� Chemical control?

� Physical control?

� What is the overall goal?

� Decapitating Fly

� The microsporidian pathogen (Kneallhazia solenopsae)

� Viruses

� Nematodes

http://www.aces.edu/pubs/docs/A/ANR-1149

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Questions/Comments

johnbarthel.wordpress.com

Thanks to Dr. Cassill, Dr. Hoare, Dr. Carvalho-Knighton, Dr.

Forys, Zoe Bass, Suzi Fox, Zoe Pratte, Kendall Moyer, Tanjim

Hossain, volunteers, and everyone who put together and

contributed to the Potential Invasive Pests Workshop

Acknowledgments