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New species of spider wasp may use chemical signals from dead ants to protect nest

A new species of spider wasp, the ‘Bone-house Wasp,’ may use chemical cues from dead ants as a nest protection strategy, according to a recent study published July 2, 2014 in the open-access journal PLOS ONE by Michael Staab from University of Freiburg, Germany, and his colleagues from China and Germany.

Wasps use a wide variety of nest protection strategies, including digging holes or occupying pre-existing cavities such as in wood. Previous studies showed that the nests of cavity-nesting wasps contain several brood cells separated by thin walls of plant debris, resin, or soil. Once the females have finished constructing the nest, laying eggs, and providing food, they construct an outermost vestibular cell to close the nest. After construction, female wasps abandon the brood and do not care for their offspring anymore. Nest protection strategies play a central role in brood survival, and in this study, scientists interested in better understanding these strategies collected ~800 nests of cavity-nesting wasps with ~1900 brood cells belonging to 18 species in South-East China.

The scientists found a nesting behavior previously unknown in the entire animal kingdom: in over 70 nests they found an outer vestibular cell filled with dead ants. The species constructing these ant-filled vestibular cell was so far unknown to science and was described in the same study as the ‘Bone-house Wasp’ (Deuteragenia ossarium), after graveyard bone-houses or ossuaries. The scientists also found lower parasitism rates in “Bone-house” nests than in nests of similar cavity-nesting wasps. The authors suggest that D. ossarium nests are less vulnerable to natural enemies, potentially supporting the outer cell’s role in defense, which most likely involves chemical cues emanating from the dead ants used as nest-building material.

Dr. Staab added, “Our discovery demonstrates in an impressive way, what fascinating strategies of offspring-protection have evolved in the animal kingdom.”

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The above story is based on materials provided by PLOS. Note: Materials may be edited for content and length.

Agriculture and Food News — ScienceDaily

Deciphering plants’ electrical signals to devise new environmental biosensors

Science is becoming closer emulating the fiction of the Avatar movie, by deciphering plants’ electrical signals to devise new holistic environmental biosensors

Plants, like almost all living organisms, have an internal communication system to respond to external stimuli. Whether they are exposed to sunlight, pollutants, nutrients or pests, plants react with a tell-tale electrical signal. Now, the EU-funded project PLEASED tries to understand these signals. If it succeeds, plants could be used as biosensors. Andrea Vitaletti, professor of computer engineering at W-LAB of the University of Rome, Italy, who is also the project coordinator, talks to about using plants as pollution sensing devices.

We already have sensors for almost anything. Why should we focus on plants?

Well, because plants evolved over millions of years in a very specific environment. They can react to a lot of different stimuli. They must do so because they cannot run away. So if you use them as biosensors they can be multifunctional. If you have an artificial device, measuring some parameter like temperature or humidity, it will probably be more accurate than the plant. But the plant needs to measure a large number of parameters simultaneously, in order to survive. So if we could read the signals of the plant we would be able to measure many parameters at the same time.

How do you intend to do that?

What we try to do is to classify the different signals plants produce in order to determine what kind of stimulus has been applied. Imagine you know which electrical pattern is typically produced by a sunflower when it is suffering from drought. Then, you could keep looking for that pattern in sunflowers. The plant will so-to-speak tell you when it wants some water through specific electrical signals.

How to differentiate between different electrical signals, which might occur simultaneously?

That is still a challenge. We simply have to conduct many experiments to recognize the different stimuli. It is going to take lot of work before we can use the plants practically as biosensors.

Why not simply look at how a plant is doing?

This is more convenient. We will interface plants with electronic devices. The plant is turned into a kind of cyborg, or plant-borg if you like. In the vision of the project to develop very small devices, the size of paperclips or even smaller, that will be put in the plant. They can collect the signals generated by the plant in its natural environment, analyze them, combine them with the signals of other plants nearby, and thus produce a clear analysis of the environment of the plant. We know it works, we have proof of concept.

Are there other reasons why we should use plants as botanical sensors?

They are robust for the simple fact that they want to live. They can be extremely cost effective. And they are pervasive; that is to say, they are everywhere.

And what could be practical applications?

They could be used for monitoring pollution of the environment, for example, or acid rain. A very practical application we have in mind is to use plants as certification devices of organic farming. By observing the signals generated by the plants, it should be possible to determine whether or not the farmer has used adequate chemicals. If you want to find out the same thing with artificial devices, you would need quite a number of them.

Where do you hope the project will lead to?

The project finishes in May 2014. By then we will have created the beginning of an open source data set of species of plants, specific stimuli and the corresponding electrical signals. What I hope is that the scientific community will continue to increase the size and the quality of this data set. Ultimately, it should be something like the Avatar movie: plants and people in close communication about the world they live in. Fantasy, science fiction, yes, but that’s the popular version of our idea.

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Agriculture and Food News — ScienceDaily