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Ants may be useful in ways we never imagined. Now a group of researchers from 16 different institutions are collaborating on a project to find out what ants can tell us about genes, environment and aging.

Pheidole
Why ants? Studying aging in ants makes sense because the different female castes - the workers (b in figure), soldiers (a in the figure), and queens, - may have the same genes and yet have quite different life spans. Also, ants are relatively long lived as insects go. Some queen ants have lived up to 30 years in the laboratory.

NYU School of Medicine researcher Dr. Danny Reinberg, Dr. Juergen Liebig, Dr. Shelley Berger and a number of other collaborators are looking at ant epigenetics, that is, the impact lifestyle and environment have on genes and gene regulation. The results may tell us more about how genes and environment effect aging in humans.

The scientists are studying three types of ants. In the big-headed ants of the genus Pheidole, like those shown in the drawing above, the soldiers may be induced artificially, allowing researchers to study the gene regulation and its consequences. They have also chosen Harpegnathos saltator, a species with no differentiation between workers and queens.  When one "queen" dies, another worker can take over the reproductive role. Finally, they chose a carpenter ant Camponotus floridanus, for its large size, complex castes, and relatively long life.

It will be interesting to see what this research uncovers.

For more information, see

Daily Media report on Dr. Reinberg's research

Dr. Reinberg's Laboratory Website

Collaborator Dr. Juergen Liebig at Arizona State University

Fountain of Youth Found in the Anthill?

What Can Ants Teach Us About Aging and Behavior?

Ants May Help Researchers Unlock Mysteries of Human Aging Process

Picture credit:  Pheidole dentata: a) normal soldier; b) normal worker from WM Wheeler, 1901. American Naturalist 35:  877-886. Wikimedia Commons

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You get to see a lot of surprising things in the Sonoran Desert of the southwestern United States. How cacti provide nectar for ants is just one example.

Most of us learned in school that flowers produce nectar, which is then collected by bees, butterflies, bats and/or moths. Extrafloral nectaries are structures on a plant that produce nectar, but they are not inside flowers. They may be located on petioles, leaves, sepals, or stems.

Extrafloral nectaries are more common than you would think. Extrafloral nectaries are found in a wide range of different plants from over 70 different families, from buttercups to violets. The primary visitors to all these extrafloral nectaries are ants.

Believe it or not, extrafloral nectaries are present in many cacti. Cacti have many specializations for saving water, and even have a different system of photosynthesis that is more water efficient.

barrel-cactus
This barrel cactus is not spineless (for the Circus of the Spineless folks).

Yet, certain species of cacti also have tiny extrafloral nectaries within patches of spines, known as thorn nectaries, which may literally drip nectar. The plant is losing water (albeit probably in very small amounts), to in attract ants. The orangish, waxy bumps in the following photo are the nectaries.

extrafloral-nectary-cactus1

Why?

No one knows for sure why the cacti have extrafloral nectaries, and it is likely that different kinds of cacti have them for different reasons. Scientists have proposed that some cacti supply nectar to ants to keep them away from the flowers, where the ants might drive away pollinators. This seems unlikely since the extrafloral nectaries are active throughout the year or at different times of the year, not just when flowers are open. The cacti may supply nectar to keep the ants away from tending aphids, scales or mealybugs that might cause more problems for the plant, although ants don’t seem to tend some of the most prominent cactus-feeding species. The cacti may supply nectar to lure ants into the area because the ants’ activity improves the texture and/or nutritional value of the soil immediately around the cacti. This last idea makes a lot of sense given desert soils are often low in organic matter and nutrients, and ants are known to improve soil. Also, ants may provide a cleaning service, keeping down disease-causing fungal spores and bacteria, as well as chasing away or eating disease-carrying pests.

Ants may chase away seed-feeding bugs like these. On barrel cacti the nectaries are active when the plant has fruit, and the seed-feeding bugs are around. Can you see the ant and extrafloral nectary in the middle, between the fruit?

cactus-bugs

Not only do a variety of native ants take nectar from cacti, but introduced species may as well.

extrafloral-nectary-cactus3

These tiny introduced Brachymyrmex gather nectar of the extrafloral nectaries of another barrel cactus. Do they perform the same duties as the native ants? Since we don't know exactly what the ants are doing in most cases, it is hard to know for sure.

Have you ever seen ants visiting extrafloral nectaries? What do you think?

The Smithsonian National Museum of Natural History has a wonderful photo gallery of ant pictures by Mark Moffett at The Hidden Life of Ants. The photograph of the bulldog ant larvae is just incredible (see communication section).You wouldn't think a larva with no legs would be able to sit up like that.

Hopefully the gallery will remain up for awhile, because I believe the exhibit itself is ending.

Maybe Miss Spider's eating habits aren't so out of line after all. In the children's books, Miss Spider eats only flowers, which in the past seemed unlikely because spiders were all thought to be carnivores. Now scientists have found a vegetarian spider. This spider is sneaky, however, because it eats food provided by plants that was intended for ants.

Acacia trees from Central and South America have a special relationship with acacia ants. Simplistically, the plant provides food and a place to live in the swollen thorns, and in return the acacia ants ward off animals that might eat the plant. The ants also remove competing vines.

beltian-bodies-bullhorn-acacia

Do you see the yellow structures on the tips of the leaves of this bullthorn acacia? Those are called Beltian bodies and they are loaded with protein. Normally ants take the Beltian bodies to feed to their larvae.

Recently researchers have found a jumping spider that takes advantage of the relationship and steals the Beltian bodies to eat for itself. Tricky spider!

References:
Herbivory in a spider through exploitation of an ant–plant mutualism
Christopher J. Meehan, Eric J. Olson, Matthew W. Reudink, T. Kurt Kyser, Robert L. Curry
13 October 2009 Current Biology
19(19) pp. R892 - R893

Veggie spider shuns meat diet at the BBC

Nice picture of spider at NPR