1. By: Melissa Neis Biology 4800
Berry Ant Mimic
By: Melissa Neis
Biology 4800

2. Examples of Other Parasite induced physiological changes
Leucochloridium: Metacercariae imitating caterpillars
Whirling Disease: Black Tail
Sacculina: Altering the ovary of females and turning the males female

3. Berry Ant Mimic Tetradonmatid Nematode: Myrmeconema neotropicum
Ant: Cephalotes atratus
Studied most extensively in Panama
This system is very unique because out a lot of the recorded systems of parasite induced physiological change plant mimicry was not among them. At first it was believed that a new species of ant had been discovered but after dissecting one of the red ant gasters, they discovered that the gaster harboured tons of eggs containing worms or rather nematodes. It wasn’t new species of ant but a new species of nematode called a tetradonematid. This system is unique because generally a tetradonematid nematode more commonly infect beetles and flies but they show not change in morphology when infecting such systems.

4. Life Cycle
This is the believed approximate life cycle, however as this system is still very new and being research it is believed that other intermediate host could be more well suited to carry on this life cycle such as: honeycreepers.
Bird excretes eggs
Foraging Ant finds fecal matter and transports it back to the hill where it feeds it to growing larvae
Larvae Ingest fecal matter and get infected with the nematode eggs
Eggs burst and larvae start to develop stunting the ants growth
Worms Migrate to Gaster where they mate and produce eggs cause physiological alteration.
The reason adult ants do not get infected because the nematode cannot pass from the midgut to the gaster due to the G.I. tract

5. Hypothesis for Possible Mimicry
Bird Predation
Other Physiological changes besides strictly appearance to aid in bird predation.
It was believed the reason for the change in the gaster (back end) of the ant was to promote predation by birds that eat berries which the parasite mimic to complete its life cycle. Along with Physiological changes it also promotes what is believed to be behavioural changes as well. However little research has been conducted thus far to prove such statements.

6. Colour Wavelength
When examining the colour produced by the ant in comparison with the believed plant it was mimicking they examined wavelengths of berries as well as size and compared them with the infected ants.
Plant is Hyeronima alchorneoides.

7. Modes of Physical Change
Red colour of gaster
Decreased ant defence: Venom
Decreased body size
Increased Weight
Weakening of the nerve that attaches the gaster to the body
Red colour of gaster
Ant Venom is one of the reason they are undesirable to birds so it is believed the nematode decreases its ability to produce its venom
Decreased body weight due to the fact that the nematode is using ant resources
Increased weight due to large volume of eggs in gaster
Worm migration and development weakens the nerve holding the gaster on which is believed to be a parasite adaptation so the bird can just pluck it off this was tested by attaching a spring scale to the gaster and pinning the ant down and pulling till the gaster was removed they also tested this by attaching the spring scale and letting the any move freely as it would normally and recorded the force required to remove the gaster of an infected and uninfected ant.

8. Modes of Behavioural change
Sluggish Movement
Gaster Flagging or holding them higher
Ant Age
Observation of the sluggish movement of heavily infected and ready to be transmitted nematodes have been observed by a group of scientists as well as the distended gasters has been a proven altered behaviour of the parasite. It was first believed that the distended gaster was the results of the extra weight contributed by the nematode however when applying extra weight to uninfected ants they found the same result was not present.
- As the ant become older and the nematode develops its roles change to foraging which serves the nematodes purpose of being ingested by the predator.

9. Behavioural and Physical Change occur simultaneously
Gaster Colour change coordinates with:
Gaster flagging
No Alarm defences were present
Ants movement became sluggish
Less Aggressive
Gaster colour is its brightest when embryos of the nematode larvae are fully developed and that when the behaviour of gaster flagging began to occur, as well as movement was slower and there normal defences to surrounding elements was non-existent.
Gaster flagging was proved to be a behavioural adaptation, researchers added weight to an infected ant and observed the ant for the same behavioural changes but none were observed indicating that the parasite must be inducing this form of behaviour.
Less aggressive when handled and produced no detectable defence pheromones
- All of this is comparable with ant not fully red that still exhibited some form of normal behaviours

10. Gaster Colour and Predation
The believed mechanism of the Gaster colour is attributed to:
Thinning of the gaster cuticle
Developing embryo's giving off a yellow colouration and secreting enzymes.
Predation on red and pink colours was tested using clay balls of multiple colours.
Researchers have also tested the preference of infected to infected by tethering ants to sticks and monitoring gaster removal.
Thinning of the gaster cuticle produces a amber colour in combination with the yellow colour of the mature embryos and possibly enzymes being secreted by the embryos themselves as the time the gaster is the reddest is when behavioural changes occur in an attempt to be ingested. The colour is close is wavelength to the mature fruits.
The Experiment for testing bird preference to the colour red and pink over all other colours combined.
Researcher noted that the removal of infected was higher than uninfected.

11. Forager Food Preference
Researcher examined all items collected by foragers :
Feces (68%)
Dead ants and insect parts (24%)
Brood: Eggs and Larvae (85%)
Unidentifiable Material (less than 1%)
Within the fecal matter there was the nematode eggs and several other parasites larvae. Mode of transmission is high through fecal matter and it is the main substrate foragers bring back to the colony.

12. Interpretation Reasoning behind fruit mimicry:
Ingested to continue life cycle
Reduced Defenses:
Increase ingestion by birds
Sluggish Behaviour
To increase amount being eaten as the birds are more likely to be alluded if the ants are more stationary
Scientists believe that the red colour that is produced to mimic the fruit that the birds generally eat is just a way for the parasite to be transmitted and dispersed to other colonies as the nematode eggs just pass through the gut and out in the feces of birds which as we have see in the life cycle and picked up by foragers.
Although not tested the reduced defences could be another parasite adaptation to increase likely-hood of being ingested as the hosts general defences are the reason birds do not eat them if they are not producing venom most likely a bird might eat another.
Interesting fact that other infected nematodes to ant due cause colour change but not to a specific part of the body.

13. Possible areas for Further Study
As this system is newly learned other areas of future study could include:
Co-adaptation of fruit mimicry with decrease in host defences and the mechanisms
Gaster Flagging: Parasite induced enzymes or general damage of the growing adults?
Examine enzyme producing of parasite to reduce host defences and gaster colour formation
Other predators as ants as not a food choice of most birds because: they have spine, hard exoskeletons and distasteful pheromones
Assumed that gaster flagging was the result of the damage done to the ventral nerve

14. References
Yanoviak et al. (2008). Parasite-Induced Fruit Mimicry in a Tropical Canopy Ant, 171(4),

15. Questions