5 replies to this topic

[FelixTheAnter]

Hi all! I have a large Lasius Niger colony with probably 1,000+ workers at this point. They just came out of hibernation a handful of days ago, no problems there at all.

I noticed that some of the workers are acting aggressively towards each other. Specifically in the long tube from the nest to the outworld. I don't see this behavior in the nest at all, and only saw it once in the outworld.

There's currently about 5 - 10 different instances of this happening in the tube. One ant will be holding another, usually by an antenna. Sometimes it will be two ants holding another, then it be one holding an antenna and one holding a leg. They don't seem to be actively trying to rip apart the "victim," they're just holding them in one spot for a long time.

Has anyone seen this before? Any idea what's happening?

[PurdueEntomology]

Ant aggression and specifically "nest-mate recognition" has been studied among various genera and species, for example " The Rules of Aggression : How Genetic, Chemical and Spatial Factors Affect Intercolony Fights in a Dominant Species, The Mediterranean Acrobat Ant Crematogaster scutellaris" (Frizzi et. al., 2015).  Studies on polygynous species have been done to understand relatedness and aggression between colony members: remember various mothers with different genetic profiles producing offspring (workers) has been shown to have incidence of aggression between nest mates.  In a generally used scoring method your description is +3 level (mandibular holding and tugging) often used in aggression studies and would be ranked as high since +5 is the highest).  Chemical cues specifically cuticular hydrocarbon profiles are the dominant way ants in both intra- and intercolonial aggression is initiated (i.e., they taste each others exoskeletons and make a determination of friend or foe).  One study (Short-time development of among-colony behavior in high-elevation ant, Krapf et. al., 2023) showed that seasonal resource availability can affect intracolony aggression.  My thoughts on this then are  since you mentioned that you have just taken them out of hibernation it may merely be a result of food and water that has instigated this aggression and that when they are fed and watered in time the aggression may subside. 

Edited by PurdueEntomology, April 5 2023 - 2:32 AM.

[FelixTheAnter]

Ant aggression and specifically "nest-mate recognition" has been studied among various genera and species, for example " The Rules of Aggression : How Genetic, Chemical and Spatial Factors Affect Intercolony Fights in a Dominant Species, The Mediterranean Acrobat Ant Crematogaster scutellaris" (Frizzi et. al., 2015). Studies on polygynous species have been done to understand relatedness and aggression between colony members: remember various mothers with different genetic profiles producing offspring (workers) has been shown to have incidence of aggression between nest mates. In a generally used scoring method your description is +3 level (mandibular holding and tugging) often used in aggression studies and would be ranked as high since +5 is the highest). Chemical cues specifically cuticular hydrocarbon profiles are the dominant way ants in both intra- and intercolonial aggression is initiated (i.e., they taste each others exoskeletons and make a determination of friend or foe). One study (Short-time development of among-colony behavior in high-elevation ant, Krapf et. al., 2023) showed that seasonal resource availability can affect intracolony aggression. My thoughts on this then are since you mentioned that you have just taken them out of hibernation it may merely be a result of food and water that has instigated this aggression and that when they are fed and watered in time the aggression may subside.

That is really interesting, thank you!
They do have a full test tube of fresh sugar water (though they aren't eating as much as I expected) and also lots of fruit flies.

Could it be related to some of the workers not being from the queen of this colony? I brood boosted this colony last year (larvae/pupae only), though I don't recall seeing any aggression between them before hibernation.

[PurdueEntomology]

 

Ant aggression and specifically "nest-mate recognition" has been studied among various genera and species, for example " The Rules of Aggression : How Genetic, Chemical and Spatial Factors Affect Intercolony Fights in a Dominant Species, The Mediterranean Acrobat Ant Crematogaster scutellaris" (Frizzi et. al., 2015). Studies on polygynous species have been done to understand relatedness and aggression between colony members: remember various mothers with different genetic profiles producing offspring (workers) has been shown to have incidence of aggression between nest mates. In a generally used scoring method your description is +3 level (mandibular holding and tugging) often used in aggression studies and would be ranked as high since +5 is the highest). Chemical cues specifically cuticular hydrocarbon profiles are the dominant way ants in both intra- and intercolonial aggression is initiated (i.e., they taste each others exoskeletons and make a determination of friend or foe). One study (Short-time development of among-colony behavior in high-elevation ant, Krapf et. al., 2023) showed that seasonal resource availability can affect intracolony aggression. My thoughts on this then are since you mentioned that you have just taken them out of hibernation it may merely be a result of food and water that has instigated this aggression and that when they are fed and watered in time the aggression may subside.

That is really interesting, thank you!
They do have a full test tube of fresh sugar water (though they aren't eating as much as I expected) and also lots of fruit flies.

Could it be related to some of the workers not being from the queen of this colony? I brood boosted this colony last year (larvae/pupae only), though I don't recall seeing any aggression between them before hibernation.

 

Well with that information then most definitely that could be your problem.

[FelixTheAnter]

Interesting. Why wouldn't it have been a problem last year? They were brood boosted mid-season, and I didn't see any issues with aggression at all.
The aggression is actuality getting worse now, there's currently two workers battling to the death in the outworld - both being ignored by all the other workers. There are probably 30-40 dead ants scattered around the edges of the outworld - not in the trash pile/graveyard area with the handful that didn't survive hibernation.

They've also been really weird about food since coming out of hibernation. I first connected them to a mini outworld from the top of the nest. They swarmed on the sugar water (unbleached cane sugar). I set up the main outworld and connected it via a longer tube, and set up their normal feeder with sugar water (plain white sugar). They were only mildly interested in it, seems like they were just taking enough to sustain themselves but not really liking it. Which is weird, because this is the same feeder/type of sugar I used last year that they regularly swarmed. I also offered a bit of honey water, which they went nuts for last year, and again they were only mildly interested in it. I'm kind of worried that there's something wrong at this point

[PurdueEntomology]

Interesting. Why wouldn't it have been a problem last year? They were brood boosted mid-season, and I didn't see any issues with aggression at all.
The aggression is actuality getting worse now, there's currently two workers battling to the death in the outworld - both being ignored by all the other workers. There are probably 30-40 dead ants scattered around the edges of the outworld - not in the trash pile/graveyard area with the handful that didn't survive hibernation.

They've also been really weird about food since coming out of hibernation. I first connected them to a mini outworld from the top of the nest. They swarmed on the sugar water (unbleached cane sugar). I set up the main outworld and connected it via a longer tube, and set up their normal feeder with sugar water (plain white sugar). They were only mildly interested in it, seems like they were just taking enough to sustain themselves but not really liking it. Which is weird, because this is the same feeder/type of sugar I used last year that they regularly swarmed. I also offered a bit of honey water, which they went nuts for last year, and again they were only mildly interested in it. I'm kind of worried that there's something wrong at this point

I feed my ants 1:2  local honey:water ( I used boiling hot water that I mix into honey) which I only leave in the feeding arenas for no more than two days at a time to reduce possible fungal and bacterial growth since the honey-water is a pathogens smorgasbord.  I have found this mixture is healthier than sugar.  You may want to try that.  Have you been providing them with a protein source: dubi roaches, meal worms, crickets?  I find that my ants over all prefer dubi roaches over other insect protein sources.  As I noted in my first comment and as can be discerned there are multiple reasons why ants of the same nest can turn on each other.  I would say try some of the food sources I mentioned and wait it out.  I have a colony of Camponotus floridanus that built of really large last year then during the winter something happened, a bacteria or possible fungus, over half the ants died.  I switched them to a new formicarium and made sure they were with low humidity, the surviving workers and queen are doing well now.  It was a close call but I thought it was best to separate the healthy from the sick and keep the humidity low.  

Upshot, it is often impossible to know what is affecting ants health wise the best we can do is look at our cultural practices, be mindful of errors and slips and move on. I wish you the best of success with your Lasius.

Edited by PurdueEntomology, April 6 2023 - 1:18 PM.