AntBlog

Alarm bells for Argentine ant UK invasion

17 October 2008 by Richard

The highly aggressive and invasive ant species, Linepithema humile (Argentine ant) is causing concern for ecologists in the UK. The South American ant has already been causing problems throughout the Mediterranean, but due to the changing climate, it now poses a risk to more northernly territories.

Linepithema humile is so successful because this species seldom attacks or competes with sister nests of the same species - unlike most other ants. In their introduced range, their genetic makeup is so uniform that individuals from one nest can enter neighboring nests without being attacked. This goes part way to explaining how and why these ants form supercolonies in their non-native range.

Unlike most native ants, L. humile is considered a pest species and commonly enters homes in search of food and water. The Argentine ant made headlines back in 2004 in Autralia when a single colony was discovered to stretch 62 miles in Melbourne posing a massive risk to local insect species.

Tags: Biology

Wildlife Trust hopes biodiversity makeover will benifit native ants

16 October 2008 by Richard

Brian Evershamm, the Conservation Director for the Bedfordshire, Cambridgeshire, Northamptonshire and Peterborough Wildlife Trust and his colleague Florent Prunier, spent several days surveying Twywell for ants in 2003, 2004 and 2005. "We were primarily trying to develop the use of small baited traps to monitor ant assemblages, in a way which could be carried out by our Ecology Group volunteers. During the study, we found several colonies of Myrmica schencki in the Whitestones area of the site. At that time, most of the rest of the site did not seem suitable for the species. Indeed, the best 'gullet' (linear ironstone quarry) habitat was densely scrubbed over, and supported just a few colonies of M. ruginodis."

As a result, when the opportunity to fund more management work at Twywell arose, Brian strongly supported the Anthills Project.

The Anthills Project was a biodiversity makeover made possible by a £20,950 grant from The Hanson Environment Fund. The grant was used to remove around three hectares of scrubby bushes and young trees that were taking over the steep gullet area. This revealed the important limestone grassland and allowed specialised flowers, such as bladder campion and wild strawberry, to make a comeback. Contractors tackled the major work while the Trust's dedicated volunteers spent two weeks clearing scrub and sycamore from the gullet as well as keeping the paths clear for visitors.

The clay grasslands at Twywell have many Lasius flavus nests, about 35% of which have Myrmica rubra, M. ruginodis and M. sabuleti nesting on their south-facing slopes. This included not only scrub clearance but also stock fencing to allow grazing.

"I hope that the use of grazing instead of mowing will benefit the range of ant species, as well as the important diversity of plant-feeding insects and molluscs for which Twywell is important."

"Since the initial surveys which showed that parts of Twywell were important for ants, the work on developing ant monitoring transferred to our reserves on the chalk of the north Chilterns in Bedfordshire, where my colleague Ed Turner has worked on ants, as well as much wider elements of biodiversity. Again, we have found small numbers of M. schencki, along with a rich ant fauna which seems to reflect the range of habitat and topography rather well. By using the syrup-baited traps, and pitfall traps, Ed has also managed to find good numbers of Myrmecina graminicola and Stenamma debile (the latter within the dense scrub on the chalk - so confirming that we need to maintain the full range of ecological conditions, and not push everything in the direction of short-cropped flower-rich turf)." Brian went on to say.

Interestingly, he has also found M. schencki on one of their acid heathland sites, at Cooper's Hill in Bedfordshire, where Ed Turner has also carried out some baited-trap trials.

Each year, the Trust runs identification workshops on ants, so that more of their active volunteers can participate in monitoring work in future.

Details of the workshop and the upcoming revisit to Twywell to carry out repeat survey work to follow shortly.

Tags: Myrmica | In the Field | Conservation

1/2 million new trees to regenerate Caledonian Forest

13 October 2008 by Richard

Once covering over 1.5 million hectares of the Scottish Highlands and home to the beaver, wild boar and even lynx (some time ago), the Caledonian Forest is today 1% of its former glory. What remains is an aged and fragmented patch, struggling to regenerate because of overgrazing by livestock.

That was, until August. The conservation charity, Trees for Life, has purchased Dundreggan Estate in Glen Moriston and hundreds of thousands of trees are to be planted over the 10,000 acres in a £1.6m deal.

500,000 native trees are being planted, which will re-connect the forest between Glen Moriston and Glen Affric. This is great news for native ants, and will serve to protect the rapidly declining numbers of wood ants in Scotland.

Tags: Conservation

Leaf cutters workers save their backs - for the greater good

11 October 2008 by Richard

Martin Burd of Monash University, Australia has been talking about how Atta colombica workers take it easy for the good of the colony.

Burd measured the work done by worker ants whose role involves collecting and harvesting leaf fragments. His recently published paper details how a lower level of productivity by foragers improves productivity within the colony.

The ants are capable of carrying up to seven times their body weight, but Burd and co-author Jerome Howard found the ants were carrying about half the maximum load they could manage. Even when the faster delivery time due to the lighter load was taken into account, they were still 35% less productive.

"What looks inefficient is actually efficiency, [it's] pretty clear they were under-performing." Burd said.

Once the leaf fragment is delivered to the colony, its tissue is processed for use to cultivate fungal gardens that provide feed for the colony's larvae. It is then transported by workers to one of the colony's fungal gardens where it is cleaned and dissected into tiny particles that are then implanted in the gardens.

Burd and Howard found the optimal leaf fragment size for peak productivity in the laboratory colonies was about 96 mm square.This was similar to the size of leaf fragments harvested in the field by the ants.

"We have shown that Atta colonies can operate at or near an ergonomic optimum. That is not necessarily apparent when the component tasks are examined in isolation." Burd went onto say.

Tags: Biology

Trap-jaw ants perform vertical take-off

10 October 2008 by Richard

I mentioned in my "What's so great about ants?" blog entry a few weeks back that Odontomachus bauri, one of the "trap-jaw" ants of the tropics, can snap its mandibles together in 0.13 milliseconds. This 60mph+ movement is the fastest recorded speed at which an animal can move its predatory body parts; peak velocities can exceed 110mph!

This speed is generated by a bite with a force of over 300 times the ants own bodyweight. This amazing clip from the BBC shows how the forces involved can propel the trap-jaw ant some distance skyward.

Tags: Odontomachus | Bauri

Community Ecology in Bird’s Nest Ferns

09 October 2008 by Tom

Tropical rainforests are hotspots of species diversity for many taxonomic groups. But why should there be so many species? How are they all able to coexist? These are the questions Tom Fayle has been seeking to answer during the course of his PhD.

"The number of species and the complexity of the interactions between them makes investigating this through the whole of the rainforest ecosystem an impractical task. I have taken a microcosm approach to this question and have focussed on a smaller part of the system in the hope that patterns observed at this scale will have relevance to larger scales. The microcosm I have used is the ant community living inside bird's nest ferns (Asplenium spp.)."

"Bird's nest ferns are litter basket epiphytes, meaning that they intercept falling leaf litter from higher in the canopy, and use the nutrients resulting from the breakdown of this leaf litter to power their own growth. The resulting spongy mass of decomposing leaf litter retains water and provides a vital refuge for canopy animals from arthropods to bats away from the hot dry conditions prevalent in the rainforest canopy. Ants are the most commonly found animal group in the ferns and perform important ecological functions, such as soil aeration, seed dispersal and predation. Multiple colonies can be found in a single fern, making them ideal for studying the interactions that occur between species. Understanding such interactions is a vital first step towards building a model of how species diversity is maintained."

Tom Fayle is a department of zoology research student at the University of Cambridge. He is at the end of the first year of this project, click here to read the article he has kindly provided to AntBlog concerning his research and findings so far.

Tags: In the Field | Biology

Ants make the ultimate sacrifice for nest security

08 October 2008 by Richard

An important function for the worker caste of many social hymenoptera is colony defence. In some species, the sting has barbs that stay lodged in a vertebrate attackers skin. The sting then detaches from the worker (sting autotomy), resulting in its death. The honey bee being a well known example.

Similarly, in some ants and termites, the defending worker's abdomen ruptures to release a sticky fluid that entangles the attacker.

These are examples of suicidal defence in direct response to attack, but during a study of social insect behaviour, researchers from the Agricultural University of Krakow, discovered a novel form of self-sacrifice in a species of ant found in Brazil.

The little understood Brazilian ant, Forelius pusillus, makes the ultimate sacrifice to beef-up its over-night nest security. As the sun sets, Forelius pusillus workers seal up the entrance to their nest. A chosen few remain outside to cover over the entrance hole until it becomes invisible. These ants then die due to the cold, or get blown away in the wind.

Dr. Adam Tofilski, who led the international research team, has been speaking to AntBlog, "We studied the ants between 2004 and 2007. As far as we know, this is the first example of preemptive self-sacrifice in social insects."

"The nests were closed every night. At this time we were not able to see any danger to the colony."

He went on to say "In social insects, foraging and other risky tasks are usually performed by older workers. Nest entrance closing is very risky, therefore I expect that the ants involved in this behaviour are old."

The task takes about 50 minutes and the technique the ants use to kick sand back-wards over the hole with their hind legs is unique to the chore, reinforcing the evidence that this is a pre-meditated activity. Once their task is complete, the ants will quickly walk away.

In order to trace the fate of these ants, the researchers placed sheets of thin plywood containing false openings over some real nest entrances back at the labs. Given the typical nest populations of 100,000, the sacrifice of up to eight workers a night is worth paying for the security of the nest.

Adam Tofilski's full paper "Preemptive Defencive Self-Sacrifice by Ant Workers", is due to be published in Novembers issue of The American Naturalist.

Tags: In the Field | Biology

NHM collections feature on stamps

07 October 2008 by Richard

I've been meaning to mention this story for a while as the stamps have been available since April. Better late than never.

The Royal Mail has produced a fantastic set of stamps, as a tip of the hat to work done by conservationists to preserve these ten British insect species. The images have been chosen from collections at the Natural History Museum and feature the Red-Barbed Ant, the Purbeck Mason Wasp, and eight others.

Full details and a flash-based stamp magnifier for viewing the stamps, available at the Royal Mail website.

Tags: Rufibarbis | Conservation | Herrichii | NHM

Ant 'infestations' major NHS concern

06 October 2008 by Richard

It seems that in some peoples minds, ants are now up there alongside MRSA and flesh eating bugs as health concerns in hospitals.

Following a freedom of information request to the National Health Service, it has been revealed that more than 300 pest infestations have been discovered at NHS Tayside sites since the beginning of this year.

Ants were top of the list, making up 174 of the 300 reported infestations (there were 39 incidents concerning mice, 7 for flies, 24 for other insects, and 6 for rats. The identity of the pests comprising the remaining 71 has not been revealed).

A patients group has gone as far as calling for NHS bosses to control the ant problem or resign. A spokesperson for the Scotland Patients Association said: "I am aghast, absolutely aghast. Patients are frightened to go into hospital as it is because of MRSA and C.diff and flesh eating bugs, this is only going to add to the stress and worry of our patients that have to go into hospital."

Formica rufibarbis update

05 October 2008 by Richard

The Zoological Society of London has been speaking to AntBlog about their involvement in the three year long Red-Barbed Ant project.

We've been told that the project will deliver conservation work for Formica rufibarbis in order to save this species from imminent extinction on the UK mainland. As well as the release of up to 25 of the 34 red-barbed ant queens and their attendant workers (a total of some 300 ants) on Chobham Common on Monday, the project aims to supplement the existing wild population in Surrey with captive-reared ants on an annual basis.

ZSL's Senior Curator of Invertebrates, Paul Pearce-Kelly, said: "It is wonderful to see that this project is now reaching the key reintroduction stage. We plan to annually rear new colonies of ants here at London Zoo for reintroduction into their natural Surrey rangeland."

A disease risk analysis has already been undertaken by ZSL vets to ensure ants released into the wild do not introduce diseases which might harm the existing colony or other ant species in England.

Julie Love, Volunteer & Education Manager of Isles of Scilly Wildlife Trust gave AntBlog this update: "We have run several shows with an interview with Dr N. Gammons and Scotti Dodd regarding the project on Radio Scilly as part of our hour long weekly show and it was featured as a news item last week."

Isles of Scilly Wildlife Trust will be keeping AntBlog up-to-date on this critical project and we should have a follow-up story in the summer. For now read the Formica rufibarbis species profile, courtesy Isles of Scilly Wildlife Trust.

^{Photo by Zoological Society of London}

Tags: Keeping Ants | Rufibarbis | Conservation | ZSL

Ants not the cooperative animals we once thought?

04 October 2008 by Richard

Ants are widely acknowledge to be a model of democracy and social co-operation. Ants put the good of the colony ahead of the needs of the individual, don't they?

New research by the National Academy of Sciences may contradict this. They've used DNA fingerprinting on five colonies of leaf-cutting ants and found that these colonies are actually "hotbeds of devious, selfish and corrupt behaviour."

This behaviour is being blamed on the "royal gene" which is carried by male ants. It would seem some males pass the gene on selectively, to ensure that their offspring become reproductive queens, not mere workers.

Dr. Bill Hughes of Leeds University who led the research, commented "...the rarity of the royal lines is actually an evolutionary strategy by the cheats, to escape suppression by the altruistic masses that they exploit." A larva's chances of becoming queen depends largely on who its father is, it had been thought that nurture was the driving force in selecting royalty - some larvae were fed certain foods to prompt their development into queens.

But now it seems those who have been passed the royal gene have an unfair advantage over the rest. Dr. Hughes went onto say "The core principle of social societies is they should be egalitarian. We've found this isn't always the case, and that some of the males are cheating. There is a genetic influence on royalty."

Tags: Biology | Atta