The insect at the bottom of those funnel-shaped pits is the larval stage of the ant lion, also called a doodlebug. Ant lions are found in warm areas throughout the world, including Florida and the southwestern United States.
The ant lion larva looks a bit like a lacewing larva, and the two are related. Here's a photo of an ant lion larva from Iowa State University. Some species have even longer jaws.
The ant lion larva digs a pit in loose dirt or sand near ant colonies. We've had a particularly dry year and there is a lot of powdery dry soil, which the ant lions seem to prefer for constructing their pits.
When an ant or other small insect falls into the pit, the larva flicks sand or soil at it to knock it towards the bottom. Once the ant is within reach, the larva grabs it and drags it under the sand to eat it.
When the larva attains its full size, it pupates. The pupa is round and covered with a layer of silk. The adult ant lion emerges from the soil. It is slender with wings with many veins that fold back over its body when it is at rest. The adult might be mistaken for a damselfly or dragonfly. Firefly Forest has a fantastic photograph of an adult ant lion.
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.
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.
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.
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.
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?
Not only do a variety of native ants take nectar from cacti, but introduced species may as well.
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?