Tuesday, June 2nd, 2015
In Venlo, Formica polyctena ants are threatened by the construction of roads and an industrial area and more recently by the construction of the Floriade flower show. On the Floriade site in 2012 there came a unique solution to prevent fragmentation of ant habitats, special ant tunnels were built. Now it is full spring, the ants are busy collecting food and the tunnels are still in use.
This photo by Arjan van den Bosch shows an ant tunnel in Venlo.
From Wildlife Extra:
Researchers in Germany have discovered that ants have a sophisticated code of conduct in high traffic areas and their own rules of the road, according to new research published in Springer’s journal The Science of Nature – Naturwissenschaften.
One of the scientists’ observations is that ants speed up in response to a higher density of traffic on their trails, rather than slowing down as might be expected.
Not surprisingly, when the researchers increased the supply of food by leaving it next to the trail, ants accelerated their speed by 50 per cent. What was unexpected was that this was despite more than double the density of traffic.
When food increases in supply, more forager ants are sent out to carry it back to the nest. With this increase in ant density, the number of encounters between outbound and incoming individuals increases.
Researchers at the University of Halle-Wittenberg in Germany suggest that the encounters provide an opportunity for ants to swap information and to change their behaviour according to conditions.
Rules of ant etiquette were also observed. For example, workers returning to the colony more often moved to the left than to the right to avoid colliding with an oncoming ant.
Rather than segregating strictly into lanes like human traffic, the ants used only a degree of segregation, with inbound ants more frequently using the left side of the trail.
The observations were made of the black-meadow ant, Formica pratensis, a species that lives mainly in open grassland and forages on aphid honeydew as its carbohydrate source.
The colonies studied were situated near favoured foraging sites where the ants protect and cultivate aphid populations. Repeated journeys in these colonies are made more efficient by the use of well-worn trails that can persist for over a decade.
A total of 1,865 individual ants were filmed on a 15cm (6in) section of trail. The video was stopped every 50 frames and the number of ants on each lane was counted. At low and medium densities, ants preferred the central lanes.
Of the total number, 496 ants were also studied for their speed. Encounters between ants included touching antennae or exchanging fluids. The number of encounters increased with density but this did not reduce the traffic flow.
“Even under the highest densities we could achieve, we did not observe any traffic jams,” says Christiane Hönicke, co-author of the study. “The ants increased their pace and were driven off the central lanes of the trail, resulting in a self-organised optimisation of the traffic.”
In this video, an ant carries a dead, much bigger, Andrena vaga mining bee to its anthill.
Matthijs Herremans in the Netherlands made this video.
This video says about itself:
Arachnid Anatomy (Orb-weaving spider)
23 November 2012
A new spin on the usual anatomy video: field biology! Basic external anatomy of an orb-weaving spider, using a live, wild specimen. This is a Cat-faced Spider (Araneus gemmoides), a common species found near/on buildings in North America. I’ve used this as a model although typically the Garden Spider (Argiope sp.) is used in zoology labs.
Also: I let a giant spider walk on my hand. Ha! But it’s OK, they don’t bite.
This video was produced by C. Ernst, a Teaching Assistant.
From Wildlife Extra:
Southern European Spiders prefer a Harvester meal (Harvester Ant, that is)
The southern European spider, Euryopis episinoides, has a distinct preference for Harvester ants, researchers have discovered, and identify them without the benefit of guidance from their parents.
The young spiderlings innately have a nose for these ants, report Stano Pekár and Manuel Cárdenas of the Masaryk University in the Czech Republic in an article in Springer’s journal The Science of Nature – Naturwissenschaften.
Euryopis episinoides is a tiny, 3mm long spider that only catches ants – in particular members of the Messor group of which there are more than 100 species.
The female conveniently lays her egg sacks close to such ant nests but this is about as much parental care as she gives to her offspring.
Once hatched, the spiderlings fend for themselves and this includes recognising and catching prey, all on their own.
The Czech researchers wanted to find out if the Euryopis episinoides spiderlings’ hunting activities were driven by convenience or truly by an innate preference for Harvester Ants.
They tested how newly hatched spiderlings that had not yet gone on the hunt reacted to the chemical cues left by three types of prey: Harvester Ants, fruit flies and Nylander Ants.
In just under half the instances, the inexperienced spiderlings assumed a hunting position in front of a paper strip carrying the smell of Harvester Ants – even though they had never before had the slightest whiff of this type of ant.
The researchers also tested the reaction of more experienced spiderlings that had been raised on only one type of prey: again either Harvester Ants, fruit flies or Nylander Ants.
They found that food imprinting changed the spiderlings’ innate food preference. This was because the spiderlings more often than not chose the type of prey on which they were raised rather than Harvester Ants.
In another twist, the spiders used in the experiment fared better healthwise when they ate ants rather than fruit flies.
“Our findings suggest that prey preference is genetically based but also affected by the experience with the first meal,” says Pekár. “Such an innate preference enables Euryopis episinoides spiderlings to rapidly gain information about prey and to successfully locate their preferred prey on their own.”
“Innate preference is beneficial as it increases efficiency in prey capture,” adds Cárdenas. “It is, however, important that spiderlings hatch near to a place of high ant occurrence, such as ant paths.”
This video from North America is called DISCOVERING THE BLACK BEAR.
From Wildlife Extra:
For a huge Black Bear, a very small ant would hardly seem to make a meal but in numbers these tiny insects are protein-packed.
Not only that, but the fact that bears eat ants is a crucial part of a complicated food chain that has wide-reaching benefits for wildlife in the US.
In a paper published in Ecology Letters, Florida State University researcher Josh Grinath examines the close relationship between bears, ants and rabbitbrush — a golden-flowered shrub that grows in the meadows of Colorado and often serves as shelter for birds.
Scientists know that plant and animal species don’t exist in a vacuum. However, tracing and understanding their complex interactions can be a challenge.
Grinath, working with Associate Professors Nora Underwood and Brian Inouye, has spent several years monitoring ant nests in a mountain meadow in Almont, Colorado.
On one visit, he discovered that bears disturbed the nests, which led him to wonder exactly how this disturbance might affect other plants and animals in the meadow.
From 2009 to 2012, Grinath, Underwood and Inouye collected data on bear damage to ant nests. In the course of this they noticed that rabbitbrush, a dominant plant in the area, was growing better and reproducing more near to the damaged nests.
This video from the USA says about itself:
18 September 2012
Rubber Rabbitbrush (Ericameria nauswosa) is in bloom now; most all other flowering plants have already gone to seed. Adult butterflies still on the wing that nectar visit these shrubs; at times several lep[idopteran] species can be found at these shrubs. Featured are: West Coast Lady, Hoary Comma, Juba Skipper, and Red Admiral.
The Wildlife Extra article continues:
Previous studies had established that ants and treehoppers have a mutualistic relationship, meaning they benefit from one another.
So the team began a series of controlled field experiments to see what would happen to treehoppers, first if there were more ants around and then if there were fewer.
They found that ants didn’t prey on the treehoppers or the rabbitbrush. Rather, they scared away other insects that typically prey on treehoppers.
In a situation where bears disturbed and ate ants, other bugs were free to prey on the treehoppers and the rabbitbrush thrived.
The study also highlighted how a modern phenomenon could end up causing more than just a nuisance.
Bears’ diets are being changed by their proximity to human habitation, and many populations are now eating human rubbish regularly instead of ants and other traditional food sources.
“Bears have an effect on everything else because they have an effect on this one important species — ants,” Grinath says.
“If bears are eating trash instead of ants, that could compromise the benefits the plants are receiving. These indirect effects are an important consideration in conservation.”