Spider Spins Ant-Repellent Silk

bazzalunatic writes "The common golden orb web spider wards off ants from attacking it on its web by spinning an ant repellent (pyrrolidine alkaloid) into its silk. It could be used to develop a new insect repellent for humans. 'This study is among the first to show animals incorporating a chemical defence as a response to the threat of predation,' says Professor Mark Elgar of the University of Melbourne."

Comments

First animal?

[Anonymous Coward]

Apparently the researcher has never heard of stink bugs, or skunks. As far as I can tell, they also have "a chemical defence as a response to the threat of predation."

Perhaps the researcher meant to refer specifically to spiders, or that the ant-repellant was the first example of chemical use to PREVENT predation, not respond to an individual threat.

Re:First animal?

[Dunbal]

Perhaps the researcher meant to refer specifically to spiders

I agree - I was going to post pretty much the same thing. Chemical warfare is evident throughout biology from bacteria and yeasts all the way up through cephalopods to mammals like the skunk. Perhaps said researcher mis-spoke, or was referring to his particular field. Either way it proves that a specialist is a person who knows a great deal about very little.

Re:First animal?

[Riceballsan]

Perhaps he's meaning this is one of the few cases of pro-active protection. Skunks, stink bugs, squids etc... use chemicals to defend themselves as a fire off at the last second defense, rather then a lace your home with it type of protection.

Re:First animal?

[NickFortune]

Animal != mammal. The summary is actually valid

The key point here is that while the set of all mammals is not equivalent to the set of all animals, it is a subset thereof. So any true statement of the form "there exists a mammal such that X" remains true if you substitute "animal" for "mammal"

Also, you'd have to consider that Animal != Arachnid. Which means that even if we accept your logic, the summary still isn't valid, since the researcher's spider would be no more valid than the GP's skunk.

Fun stuff, logic :)

Females

[JohnConnor]

Old news... Cobwebs at my place have been repelling all kinds of females for a long time, not just my aunts.

Re:Females

[Anonymous Coward]

Interestingly enough, I have observed that the opposite is also the case. The presence of females appears to be repelling cobwebs !

Spiderwebs and ants...?

[lexsird]

Is that spider a picky eater? Spiders will eat ants; I used to drop big black ants into spider webs as a child to watch the mayhem. Ants panic when they find themselves in the middle of a spider web, it's almost instinctual that they are in serious trouble. The spider wakes up and is like "WTF?" and will dart out and put some serious bites to it.

I don't know about fire ants though, they might be hard to eat, or they might be prime rib for spiders. Just as long as they get the first bite in on them, it's all good.

I think there is more to being "ant repellent" than a chemical, right?

Re:Spiderwebs and ants...?

[Dunbal]

A spider will eat one ant. It has trouble coping with thousands or even hundreds of thousands of ants at a time, however. I think the defense mechanism is to avoid the spider getting ambushed by a roving ant army, but any lone ants can be dealt with with the usual efficiency.

Re:Spiderwebs and ants...?

[Dunbal]

That is a handy type of repellant, but will the Ants become immune to it after a while

Why? That's the good thing about a repellent: it does not kill ants. So unless you have ants that can only survive by eating spiders, a repellent should not affect the evolution of the ants in any way. They will just move out of the way and find something else to scavenge. Now if you start guarding all their food-sources with this repellent and put evolutionary "pressure" (ie, overcoming this chemical puzzle means significant advantage and survival likelyhood compared to other ant colonies) you might see resistance. But otherwise, no.

Huh?

[jurgen]

"'This study is among the first to show animals incorporating a chemical defence as a response to the threat of predation,' says Professor Mark Elgar of the University of Melbourne."

That sentence is absurd coming from a biologist... either it's a misquote, or this professor smoked some strong stuff... Biology is FULL of chemical defences as a response to the threat of predation, and chemical offences for that matter. They are common in the insect world, and practically universal in the plant and microbial worlds. In fact looking at Biology as a whole, the majority of what evolution does on a day-to-day basis is developing new chemical defences as a response to the threat of predation. Perhaps repellents are a little more unusual in the animal (as opposed to plant) world or less well studied, but hasn't he ever heard of i.e. skunks? By the time we narrow this sentence down to something that makes sense it's a big yawner: "This study is amongst the first to show animals incorporating a chemical repellent targeted at specific predators into secretions they use to build external structures (webs)." Hmmm.

Re:Huh?

[hldn]

Perhaps repellents are a little more unusual in the animal (as opposed to plant) world or less well studied, but hasn't he ever heard of i.e. skunks?

excellent misuse of i.e.

Wait I thought Lacewings did this

[NotSoHeavyD3]

Admittedly I can't find it.(My GoogleFu is weak today.) I know they lay their eggs at the end of long threads to protect them. I thought I read somewhere that the threads have a chemical repellent to keep ants away (Since you'd think one tiny ant would just climb down and get it) but I can't find anything on Google confirming that.