Las hormigas preparan un coctel de antibiótico para proteger la colonia.

Wood ants combine tree resin with formic acid to protect their nests from fungi and bacteria.

Simon Williams/Minden Pictures


‘Chemist’ ants brew antibiotic cocktail to protect their colony

Ants have all sorts of jobs we normally think of as human, from architect to farmer to insect-in-chief. Now, scientists are adding one more occupation to that list: chemist. A new study shows that wood ants protect their colonies from disease by crafting a potent antibiotic “cocktail” made of tree resin and poison from their own bodies. The finding, one of the most sophisticated examples of animal pharmacology, could explain how some ants evade epidemics.

Like humans, wood ants (Formica paralugubris) live in dense groups, with colonies numbering in the hundreds of thousands. That should make them prime targets for widespread disease, especially because their nests are warm, humid, and full of dead insects to be used as food. Most ant species manage to avoid epidemics by grooming each other and obsessively cleaning their colonies, and wood ants take the added precaution of collecting antimicrobial tree resin to bring back to their nests. But Michel Chapuisat, an evolutionary biologist at the University of Lausanne in Switzerland, suspected this species might be hiding an even more sophisticated secret for staying healthy.

To investigate, Chapuisat and his colleagues first measured how well wood ant–exposed resin warded off a deadly fungus—which infects ants and spreads through spores grown in their bodies—compared to tree resin alone. In petri dishes covered with the fungus (Metarhizium brunneum), resin stored with the ants for 2 weeks resulted in a 50% larger fungus-free area, the team reports this month in Ecology and Evolution. Stones and twigs, both common in nests, didn’t get any antifungal boost from being around the ants. That was an indication that something special was happening between wood ants and resin.

Next, the researchers used liquid chromatography, a technique for analyzing chemical mixtures, to spot any substances left behind by the wood ants. One compound they found was formic acid: a caustic substance produced by several ant species to fight off threats, subdue prey, and clean their offspring. When the scientists dipped tree resin in the acid, they found the resulting mixture did a better job of warding off fungus than resin alone, or glass dipped in formic acid. That was enough for the researchers to confirm the ants are mixing the two substances—one found, one created—to keep their nests healthy. “They exploit the tree and then they combine it with their own poison,” Chapuisat explains.

“I thought it was a really interesting and exciting paper,” says Michael Singer, an evolutionary ecologist at Wesleyan University in Middletown, Connecticut. Plenty of animals defend themselves with substances they find or create, but Singer says this new substance shows unique “synergistic effects,” meaning that the mixture of resin and formic acid is more than just the sum of its parts. The only other example of an animal brewing up a combination like this—which Singer calls “defensive mixology”—is humans and our drug cocktails.

But rather than springing suddenly from the mind of a brilliant human inventor, this mixture is the result of a long evolutionary tug-of-war. “Ants have been coevolving with their pathogens for 50 million years,” and perhaps longer, says Christopher Pull, an evolutionary biologist at the Institute of Science and Technology Austria in Klosterneuberg. And for now, the insects seem to be keeping their microbes at bay. With issues like antibiotic resistance making human drugs less effective, Pull says the time-tested strategies of ants may be worth a closer look. “Maybe they’ve come up with viable solutions to these problems we’re just now encountering.”

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Las hormigas de África y Madagascar

Con más de 2.000 especies en Africa y mas de 600 en Madagascar las hormigas son el animal social dominante en las regiones tropicales de este continente y de la siempre mágica Madagascar.


 Este marabilloso libro “Las hormigas de África y Madagascar” introduce a los lectores en el mundo fascinante de la fauna mirmecológica de estas zonas del mundo con claves identificativas de familias y subfamílias ilustraciones así como claves para separar géneros, mapas de distribución, datos de la ecología de las hormigas y su historia natural, e incluye una lista de todas las especies de hormigas actualmente reconocidas en las regiones. Esta detallada guía es una herramienta esencia para entomólogos, mirmecólogos y cualquier aficionado interesado en la fauna mismecológica de la zona.

Hormigas de Africa y Madagascar

 

 

 


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La oruga Carnivora y mentirosa. (Inglés)

La oruga Carnivora y mentirosa

Un raro grupo de orugas carnívoras ha logrado sobrevivir durante millones de años engañando y, a veces, comiendo a sus amigos insectos.

 A rare group of carnivorous caterpillars have managed to survive for millions of years by duping and sometimes eating their insect friends 

Caterpillars, they’re a bit soft, aren’t they? Unappreciated ugly creatures, waiting for their metamorphosis.

All they do is slowly crawl around, munching on plants until they literally spread their wings and fly away.

While the majority eat only plants, a certain group has evolved curious, clever ways to eat other unwitting insects.

They mostly feed on soft bodied, sap sucking insects such as aphids (plant lice), ant pupae and larvae. These victims are often duped into a false sense of security by these caterpillars’ sneaky tactics.

Some even embed themselves within ant nests and are fed regurgitated food from ants themselves, like cuckoos in a nest.


Living harmoniously... for now (Credit: David J Lohman)

Living harmoniously… for now (Credit: David J Lohman)


These “wolves in sheeps’ clothing” use a chemical camouflage to mimic the ants’ smell which deceives them into thinking they are one of their own.

Others embed themselves within a group of tasty aphids that the ants herd for honeydew, but go undetected as once again they copy the smell of their aphid prey.

“I refer to this as a cloak of invisibility,” said David Lohman of City University of New York, US. “They eat aphids but the aphids’ own protective ants don’t attack them.”

Masters of sneak

This group, the Miletinae, are a subfamily of the second largest group of butterflies, Lycaenidae, and are found on four continents.

And they are extremely rare, the 140 species represent less than 1% of the 175,000 or so different species of Lepidoptera, the group that includes butterflies and moths.

(Credit: David J Lohman)

(Credit: David J Lohman)

They are so rare that a new study looking at the evolutionary history of this particular group took 20 years to collect enough samples to study their family tree.They have really cracked the code for ant communication

The authors behind the research, published in the journal Evolution, wanted to understand the effect their unusual, predatory lifestyle had on their evolution.

Shifting from a plant-based diet to eating insects itself is not that rare, but those species who make the change usually do not survive for long, explained Dr Lohman, who is one of the lead authors of the study.

This small group has therefore long puzzled researchers: how did they manage to survive this lifestyle whereas other had not?

The answer, it is now apparent, lies with ants.


Friend or foe? (Credit: David J Lohman)

Friend or foe? (Credit: David J Lohman)


The Lycaenidae family’s historical relationship with ants has been key to helping the Militinae occupy their dietary niche, said another co-author of the study, Naomi Pierce of Harvard University in the US.

Whereas the former can be beneficial to the ants, sometimes even making them a nourishing sugary substance, the latter are parasites.

Ant ghosts

“They have really cracked the code for ant communication. They secrete chemicals on the surface of the larvae that appeases the ants so the ants don’t attack the caterpillars,” said Prof Pierce.

The reason Militinae were able to evolve and persist in this carnivorous niche is therefore precisely because they have this pre-adaptation of living and co-operating with ants, she added.

But not just any ant will do, the researchers discovered. Just as plant-eating caterpillars only eat certain species of plant, carnivorous caterpillars eat particular groups of ants.


This caterpillar mimics the smell of its prey (Credit: David J Lohman)

This caterpillar mimics the smell of its prey (Credit: David J Lohman)


“The close relatives of one lineage will associate with certain closely related ant species. We call this the ghost of ant association past as there’s no relation between these caterpillars and ants other than they are feeding on insects tended by a particular group of ants,” Prof Pierce told BBC Earth.

This association therefore ensures the caterpillars will always find their prey.

Lohman said it was possible that butterflies could even be sniffing out ants their future caterpillars could exploit to survive.

During his field work in Asia he noticed that a group, whose caterpillars feed on aphids, would circle ants even when there were no aphids present.

“It makes sense that this habit of living with ants has been passed on from one generation to the next. It has predisposed them to finding ants and along with the ants they often find the insects that they eat,” Dr Lohman said.


Butterflies circle ants their offspring might later feed on (Credit: Zofia Kaliszewska)

Butterflies circle ants their offspring might later feed on (Credit: Zofia Kaliszewska)


This parasitic relationship is nothing new. When reconstructing the Miletinae’s family tree, the team found that their family was up to 60 million years old, a time when forests thrived and covered much of Earth.

Their rare dietary habits persist when they become butterflies.

Unlike most which drink nectar, adults of this carnivorous group drink the honeydew secretions of aphids and other sap-sucking insects, the same ones their larvae offspring will later eat.

Follow Melissa Hogenboom and BBC Earth on twitter.


Searching for honeydew (Credit: Zofia Kaliszewska)

Searching for honeydew (Credit: Zofia Kaliszewska)


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El cebo resistente al agua es una mejora para el control de las plagas de hormigas

Water-Resistant Bait Could Deliver Much-Needed Improvement in Pest Ant Control

Red imported fire ants


 

The red imported fire ant (Solenopsis invicta) can be controlled through baits, which workers carry back to the colony, thereby spreading the active ingredient that inhibits the ability of colony’s queen to produce eggs. Standard ant baits, however, break down in moist conditions. A new water-resistant bait shows promise. (Photo credit: USDA APHIS PPQ – Imported Fire Ant Station, Bugwood.org)

The red imported fire ant (Solenopsis invicta) and the little fire ant (Wasmannia auropunctata) are just two species of invasive ants that have thrived since their introduction to the U.S. The former has spread through much of the southeastern United States, while the latter has become widespread on the Big Island of Hawaii. In both locales, however, moisture in the environment means existing bait control methods have limitations.

Baits for fire ants have mostly gone unchanged since they were first developed in the 1960s—half a century ago—despite the significant drawback that the typical bait carrier breaks down in wet conditions. However, a new ant bait formulation that is water-resistant offers promise, say researchers with the United States Department of Agriculture’s Agricultural Research Service (USDA-ARS). Their comparison study is published today in the Journal of Economic Entomology.

A team led by Robert K. Vander Meer, Ph.D., at the USDA-ARS Center for Medical, Agricultural, and Veterinary Entomology in the Imported Fire Ant and Household Insects Research Unit conducted an experiment that deployed existing ant baits and water-resistant baits in closely matched wet conditions. Both baits carry an active ingredient that inhibits the ability of an ant colony’s queen to produce eggs. At the end of the 13-week test period, half of the red imported fire ant colonies exposed to standard bait were no longer producing worker ants, while none of the colonies exposed to the water-resistant bait were producing workers.

Vander Meer says the experiment was designed carefully to ensure that similar-sized ant colonies were compared and that they were exposed to baits under the same moisture and temperature conditions. “If you’re comparing two formulations of the same insecticide, at the same rates, then you have to control variables as much as you can, or else you’re not going to be able to show significant differences between the two,” he says. “We were very happily surprised.”

The water-resistant, or hydrophobic, ant bait, Erasant, is produced in Taiwan, by Chung Hsi Chemical Plant Ltd. The company has a U.S. patent, but the bait is not currently available in the United States.

“Our objective is to ultimately provide better control tools to the public for the control of pest ants and, in particular, the fire ant. Ideally, we would like to see this appear as a product at some time in the future here in the U.S., because I think it could be very useful in terms of providing a very good control method that is not affected by the heavy moisture that we deal with in the southeast,” says Vander Meer.

USDA-ARS is conducting further testing of the water-resistant ant bait, in irrigated plant environments in California and Florida as well as tropical areas such as Hawaii.

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Las feromonas de las hormigas se pueden utilizar para ahuyentarlas. (Inglés)

Pheromone Research May Lead to New Insect Control Methods

Each year in the United States, fire ants cost $7 billion for control, damage repair, and medical care. They infest millions of acres in urban, agricultural, wildlife, recreational and industrial areas.


In order to combat the the red imported fire ant, scientists at the USDA’s Agricultural Research Service are studying pheromones that are secreted by the ants. Pheromones signal alarm, mark trails to food, attract workers to brood and the queen, and unite males and females for mating.

Entomologist Man-Yeon Choi and chemist Robert Vander Meer have shown for the first time that a neuropeptide called pheromone biosynthesis activating neuropeptide (PBAN) activates production of trail pheromones in ants.

PBAN was first discovered by ARS scientists in Beltsville, Md., in the 1980s. They found that the hormone regulates sex pheromone production in female moths. Since then, scientists have found that other insects, including cockroaches, have this type of PBAN family peptides made of two or more amino acids.

Choi injected fire ant workers with PBAN peptides and found a significant increase in pheromone production. He and Vander Meer also identified the DNA sequence of both the PBAN gene and receptor gene, which allowed them to test the function of PBAN in trail pheromone production using a new technique called RNA interference (RNAi). This involves taking normally single-stranded RNA from a gene and making double-stranded RNA (dsRNA) that can be used to suppress that gene’s expression.

When scientists injected dsRNA of either the PBAN gene or receptor gene into ants, they found that ants produced less trail pheromone. They also discovered that adult ants and larvae injected with PBAN-RNAi had significant mortality, compared to ants that didn’t receive the injection. Pupae that received the treatment had delayed development and a high death rate.

“This gene has many different roles. When we disrupt the expression of it with RNAi, we observe multiple effects in immature stages as well as in adults,” said Vander Meer.

The scientists also applied their PBAN RNAi work to the corn earworm — a moth species that is a serious crop pest.

“Our moth study was very extensive,” Vander Meer said. “We fed the PBAN RNAi to corn earworms in their standard laboratory diet, and it had dramatic effects.”

Those effects included a decrease in growth rate and the inability to develop from larvae into pupae. Female moths that survived to adulthood had decreased amounts of sex pheromone.

The scientists plan to investigate whether other pheromones are activated by PBAN, and if dsRNA can be used for fire ant control.

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Las ranas frenan a las hormigas de fuego. (Inglés)

Compounds from Poison Frogs May be Used to Control Fire Ants

Tropical fire ants (Solenopsis geminata), which are native to Central America.

USDA scientists and their collaborators have found that naturally-occurring compounds that are found on the skin of certain poison frogs can incapacitate and kill fire ants.

The red imported fire ant (Solenopsis invicta) damages crops, devastates small animal populations, and inflicts painful stings to livestock and to humans. To determine whether poison-frog alkaloids would kill fire ants, scientists at the USDA-ARS’s Center for Medical, Agricultural, and Veterinary Entomology (CMAVE) partnered with researchers at the Smithsonian Conservation Biology Institute and others from the National Institutes of Health.

“After finding that the frogs had unique alkaloids, NIH scientist John Daly, now deceased, began exploring possible medical applications of the compounds,” said Robert Vander Meer, research leader for CMAVE’s Imported Fire Ant and Household Insects Unit. “Over the years, scientists have identified and isolated about 900 alkaloids from the skin of poison frogs.”

Poison frogs, natives of Central and South America, do not produce alkaloids. Instead, they sequester them by eating ants (including fire ants), mites, millipedes, and other arthropods that produce these compounds, according to Vander Meer. He and his colleagues developed a bioassay to measure the toxicity of 20 poison-frog alkaloids, some of which were very effective in controlling fire ants, while others were not.

Alkaloids derived from mites and found on the skin of Central America’s poison frog, Oophaga pumilio, were more effective at incapacitating fire ants than the fire ants’ own alkaloids.

“Interestingly, this same frog has a varied diet of ants and mites,” Vander Meer said. “Mite-derived alkaloids have also been reported on O. pumilio’s skin, and these compounds were found to be highly effective at incapacitating S. invicta.”

Scientists are considering expanding their research to include mosquitoes. Earlier work published in the Proceedings of the National Academy of Sciences demonstrated that a poison-frog alkaloid called pumiliotoxin 251D was effective against the yellowfever mosquito (Aedes aegypti). Insects that landed on surfaces treated with the compound could no longer fly and died. In the future, poison-frog alkaloids or derivatives may prove useful in helping to control mosquitoes, according to Vander Meer.

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