Allocation of Resources: Ants and their Young

Ashley Hendersonavh6@columbia.edu

Facts: Solenopsis saevissima

• Order and Family: Hymenoptera Formicidae Myrmicinae

• Like all ants, fire ants are social animals and live in colonies where they work together to gather food, raise young, and protect the nest from invaders.

• Common name: Fire Ants, or Lavapes

• Light brown/ reddish color

• Found primarily in grassy areas in southern Brazil, Argentina, and Uruguay

• Has also been exported to southern U.S.A., especially Alabama and Mississipi

• Known for its painful sting

A Colony Post-Destruction and the precious Young Inside…

Roles of Ants in a Colony…

• Queen ant: – 6-8 mm long

– Black

– Winged

– Starts colony

– Sole purpose is to mate and lay eggs

– When a colony has multiple queens, one is the dominant alpha queen

• Males:– Fertilized eggs

– 6-8 mm long

– Black

– Winged

– Sole purpose is to mate with queen

• Worker ants:– Sterile females

– 3-5 mm long

– Brownish/ Reddish

– Nurses that care for the young

– Foragers that find food

– Mound builders

– Soldiers that defend the nest

– Role of worker ant is determined by size and age of ant

Some Fire Ants…

Stages of Development…

• Queen mates with a male in the air• She lays eggs deep in the center of the ant colony, near the

ground• From egg larva takes 7-14 days• From larva pupa takes 12-15 days• From pupa adult takes 10 days• Egg: inside queen and very small and white when laid• Larva: white, fat, round, teardrop shaped with hooked tip,

ridges on the back, range from 2-5 mm long• Pupa: white, ant-shaped but without legs, 2-5 mm long• Winged Pupa: black, ant-shaped with wings, 6-8 mm long

The Question…

• Because they have already invested more resources into pupae and because pupae are closer to becoming adult ants, do ants place a higher priority on protecting pupa than they do on protecting larva?

• H0: There will be no significant difference between the average recovery time for larva and the recovery time for pupa.

• H1: The recovery time for pupa will be significantly faster than the recovery time for larva.

The Approach…• 8 Anthills were found in the pastures of Sao Paulo, Brazil in areas

surrounding the points 2312’00.914”S, 4621’23.442”W, and 2312’10.205”S, 4621’30.840”W.

• The data were collected on 18/VI/2001, 22/VI/2001, and 26/VI/2001 between 12:00 p.m. and 4:00 p.m. Temp: 75º F

• The anthills were disturbed with a stick as much as was necessary to expose the young buried in the center of the colony.

• One larva was picked up and placed on the top of the disturbed anthill. The time until an ant retrieved it and carried it under the soil was recorded. This was repeated 5 times for larvae and 5 times for pupae at each site. At the sites where winged pupae were present, it was also repeated for them.

• The results were graphed and statistically analyzed with ANOVA.

Results…The ants were shown to rescue the pupae at a

significantly faster rate than they rescued the larvae. At all of the sites, the average pupae time was shorter than the average larvae time. According to ANOVA, the critical F value was 3.12, and the F for the data was 8.37, meaning that the data was clearly significant. The p value was .005, meaning there was only a slight chance of uncertainty.

Larvae Recovery Time

0

10

20

30

40

50

60

70

80

90

100

1 6 8 3 7 2 4 5

Anthill Number (in order of decreasing circumference)

Re

co

very

Tim

e (

se

c)

Larvae Avg. (s)

Pupae Avg. (s)

Winged Avg. (s)

Conclusions…

• Ants place a higher priority on protecting pupae than larvae.

• Since they rescue winged (male and queen) pupae faster than worker pupae, they clearly place even more importance in ants with reproductive abilities.

• Queens and males do not have the ability to defend the nest or care for the young and are concerned only with their own survival. Workers are responsible for defending the nest and rescuing the young.