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Time to knock the cobwebs off this blog with some new posts. Let's start by taking a look at ants tending the aster hopper, Publilia concava.

This species of treehopper is relatively easy to find because the nymphs feed in aggregations on the underside of goldenrod leaves (Solidago altissima).

The relationship between ants and aster hoppers is a mutualism. The ants guard the treehoppers and drive away predators. In this case the ants were Formica sp.

In return, the nymphs supply food for the ants in the form of liquid honeydew. In the center of the photograph the nymph has curled its tubular abdomen to present food to the ant.

The adult female treehoppers lay their eggs in clusters and guard them until they hatch. Then the worker ants take over. In a recent study, Morales and Zink found adult female treehoppers with ants tending them were more likely to lay eggs than untended ones. At one site the researchers discovered egg laying per treehopper actually increases with the number of worker ants nearby.

If you've never watched ants tending aster hoppers, here's a short video. (Unfortunately, the lighting conditions weren't ideal and there was a breeze.).

You might think that the treehopper nymphs, as phloem feeders, would be rather sessile, but the nymphs move around more than you might expect. Morales and Zink suggest that treehoppers may respond to density of conspecifics as well as ants.

In any case, the relationship between aster hoppers and ants is an interesting one.

Have you ever seen aster hoppers tended by ants?

Reference:

Morales MA, Zink AG (2017) Mechanisms of aggregation in an ant-tended treehopper: Attraction to mutualists is balanced by conspecific competition
PLOS ONE 12(7): e0181429. https://doi.org/10.1371/journal.pone.0181429

Morales, 2002. Ant-dependent oviposition in the membracid Publilia concava. Ecological Entomology. 27:  247-250. (download .pdf)

Previous post about the treehopper on thistle, Entylia carinata

The rush milkweeds are flowering.


The open flowers attract an array of insects.

For example, tarantula hawks seem to prefer milkweed flowers. In fact, they are one of the chief pollinators of the plant.

No surprise that rover ants also visit.

From the swollen appearance of the metasoma of the upper ant, it looks like the worker ants are feeding on nectar.

Wait, the nectaries aren't open on these buds.

It can be hard to think of something as small as a rover ant as a predator, but they do catch insects like this thrips.

The tarantula hawks, on the other hand, probably aren't in any danger.

 

There's a question for the Consult-Ant this week. (The “Consult-Ant” started on the Leaping from the Box website, where I answered questions about ants and ant farms. From now on I will post the answers here, and when Karen has time she will also post the answers on her site.)

Question:

I sucked an ant up in a homemade bug vacuum and then transported it over a mile from its home.  Will it survive if I let it go?  Do they have to find their way to their original nest in order to survive?

Anon

Answer:

First of all, can a single ant make it on its own? The answer is no, unless that ant is a queen during certain parts of her life cycle. A single worker ant on its own doesn't have much of a chance of survival.

So, could the ant navigate back to its nest if displaced? Different ants use different cues to navigate when outside the nest. Some ants can use cues from polarized light or the position of the sun. Potentially an ant that uses visual cues might be able to re-orient itself over short distances to find its nest.

On the other hand, some ants rely heavily on chemical trails to move back and forth to their colony. Think of army ants, some of which are blind. In that case, the ant would have to wander around until it accidentally ran across a trail. The likelihood this would happen decreases with distance from the nest.

At the distance of over a mile, the chances the ant will be re-united with its nestmates are non-existent. There's a tiny chance it could join a nearby colony, but it is not likely.

What about a flying insect, like a honey bee? Honey bees would stand a much better chance. They have been shown to be able to fly up to five miles from their hive while foraging. They navigate by visual cues. An experienced forager bee might be able to re-orient from a greater distance than an ant on the ground could.

Please let us know if you have any further questions.

Anyone else have any thoughts?

 

Photograph of ant in a bug sucker by Karen Gibson, used with permission.

2

When the weather is cold and cloudy, many people dream of sunbathing on a warm, tropical beach. What about ants? Evidence suggests that at least some ants spend time basking in the sun.

See, for example, this video of harvester ants (Pogonomyrmex) sitting in the sun after a rain.

News From Rockcliff Farms blog has photographs of imported fire ants (Solenopsis invicta) sunbathing in large groups during a midwinter warm spell.

Some possible reasons for sunbathing/basking:

  1. Warm up or increase body temperature, particularly in poikilotherms (animals whose internal body temperature varies with the external environmental temperature)
  2. Exposure to ultraviolet light can kill microorganisms, such as bacteria, on the outer surface
  3. Exposure to ultraviolet light in vertebrates induces the production of Vitamin D

 

In his 1995 book Animal Architecture, Juhani Pallasmaa stated wood ants (Formica sp.) use heat captured by basking in the sun to warm their nests.

Kadochová, Frouz, and Roces (2017) recently tested this idea in the laboratory. They found Formica polyctena workers are willing to bask under an artificial heat source, which in this case was an infrared lamp. The authors of the paper didn't find evidence basking workers had a sustained increase in metabolic rate, but did suggest that heat energy absorbed during sun basking can be dissipated enough to increase the temperature inside of the nest. Cool! (yeah, I couldn't resist.)

The authors of the study found certain behavioral castes bask more than others. It would be worth investigating if workers which spend more time with the brood are more likely to bask. The ability to increase the nest temperatures around the brood during cold spells would likely be an advantage.

What do you think?

References:

Kadochová Š, Frouz J, Roces F (2017) Sun Basking in Red Wood Ants Formica polyctena (Hymenoptera, Formicidae): Individual Behaviour and Temperature-Dependent Respiration Rates. PLoS ONE 12(1): e0170570. doi:10.1371/journal.pone.0170570

 

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Pallasmaa, J. 1995. Animal architecture. Helsinki: Museum of Finnish Architecture. 126 p.