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Posts Tagged ‘fire ants’

Have Australians lost their fight against imported fire ants?

Despite $215 million being poured into eradication programs nationally, fire ants have claimed territory in an arc from Logan City, between Brisbane and the Gold Coast, to near Grandchester, about 80km west of where the first outbreak was found at the Port of Brisbane in 2001.

Authorities now concede a new and even more expensive long-term campaign might be needed to stop them threatening our lifestyles.

I am curious as to how fire ants threaten the Aussie lifestyle, though. Do they eat Vegemite?

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A Solenopsis invicta queen attempts to escape a pair of tormentors

Life is perilous for young ant queens. This fire ant (Solenopsis invicta) is being pursued by native Forelius ants after her mating flight in central Florida. She frantically climbs a grass blade to escape, but to no avail- the attackers follow. She will make an excellent source of protein to feed the Forelius larvae.

Two larger points about this photo. First, establishing new colonies is tremendously difficult. The founding stage is when most colony-level mortality happens, and this excessive mortality is why ant nests produce hundreds of queens every year in the hopes that a handful survive.

Second, native ants may be our best friends in combating the spread of introduced pest ants. Healthy, intact native habitats with thriving local ant populations make it more difficult for intruders like the fire ant to gain a toe-hold. The more we alter habitat and the more we use generalized pesticides, the more problems we cause our native species and the easier it is for pests to establish.

Photo details: Canon 100mm f2.8 macro lens on a Canon EOS 20D
ISO 400, f/8, 1/500 sec, ambient light

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The port at Mobile, Alabama, photographed from across the bay.

The port city of Mobile, Alabama holds special significance for students of ant science.  Jo-anne and I took a weekend trip down to the gulf coast in January, and as we are both myrmecologists we felt compelled to stop and take a few photographs.  Not only is Mobile the childhood home of ant guru E. O. Wilson, but the city’s docks have been the point of introduction into North America for some notorious pest ants.  We’d have neglected our intellectual heritage to just drive through.

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Solenopsis invicta- invasive or just disturbed?

Solenopsis invicta - invasive or just disturbed?

Prevailing wisdom holds that imported fire ants marched across the southern United States on the virtue of their fierce nature and superior competitive ability.  The fire ant conquest of the south reads like a tale of bravery and intrigue, but according to Walt Tschinkel and Josh King it is also not true.   They have a must-read study in PNAS this week detailing a tight set of field experiments that turns the conventional wisdom upside-down.

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Does ant activity cycle by an internal clock, or is their activity cycle a response to changing environmental cues?

A study in Insectes Sociaux weighs in on the side of environment. Penick & Tschinkel experimented with applying light and heat from different directions and at different times of day to fire ant mounds.  It turns out that the ants’ daily rhythm of moving their brood around the nest is a result of temperature tracking.  I’ve pasted a link to the article and the abstract below.

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Camponotus personatus

Paraguay may be the world’s most important country. Never mind that it is economically isolated and geopolitically forgettable. Rather, I measure importance by less trivial metrics, and by that of course I mean ants.

Paraguayan ants have changed the world. Many of the world’s worst pest species evolved on the broad plains of the Paraná river before hitchhiking with human commerce to points abroad. The infamous fire ants in the southern U.S. originated on the Paraná, as did the Argentine Ants that plague California and Europe, along with a rogue’s gallery of other trampy and invasive species. These invasives transform ecosystems and drive native species to extinction. Not to mention that some of them are champion stingers and are very good at getting into houses, greenhouses, and wherever else they can stir up trouble.

We do not know why ants from this region are so potent, but perhaps something about the Paraná acts as a cradle for pestilence. Sadly, we’re a pretty long way from finding out, as the ant fauna in that part of the world has been among the most poorly-documented anywhere. We know a fair bit about what happens to these ants after they arrive in Europe, Hawaii, Florida, and other places frequented by scientists, but what goes on in the native range is largely a black box. I’ve been slowly been chipping away at the problem by cataloging the ant species that live in Paraguay. You can check out the progress- accompanied by April Nobile’s amazing ant images- here:

The Ants of Paraguay

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For more details, the full catalog is here (full text is subscription only, sorry):

Wild, A. L. 2007. A Catalogue of the Ants of Paraguay (Hymenoptera: Formicidae). Zootaxa 1622: 1-55.

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