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Brachymyrmex depilis Invasion!

Posted: Tue May 15, 2018 12:43 pm
by AntsDakota
A year or 2 ago, I had never even seen Brachymyrmex depilis in my entire life. Last year, I found 2 colonies in my yard. I have noticed they can grow extremely fast, and there are hundreds of workers in the nest between the time of their nuptial flight last fall, and now in May. They are rapidly increasing their numbers around my back yard, and here's why I call it an invasion - many of the new nests reside where peaceful Lasius nests used to exist last fall! They most likely either drove the Lasius colonies out of their nests, or killed them! Now almost all Lasius colonies in my yard are replaced by these rapidly growing Bd colonies. Here are 3 reasons why the Lasius colonies may be out competed. 1-Brachymyrmex are aggressive, while Lasius neoniger/alienus are not. 2-Brachymyrmex grow much faster than Lasius. And 3- Brachymyrmex are highly polygynous, and Lasius are not. (I once found a Bd colony with almost 20 queens! :o) So, I have also heard that their cousin, Brachymyrmex patagonicus are invasive and spreading across the southern U.S. Any advice on how to make sure Lasius doesn't disappear from my yard is greatly appreciated.

Re: Brachymyrmex depilis Invasion!

Posted: Tue May 15, 2018 2:28 pm
by antnest8
I really hate invasive species i do but, have you ever thought that in nature to strongest survive and maybe even if we had not introduced species another more competitive species would have taken their place anyway. I still think that us being the introducers is wrong

Re: Brachymyrmex depilis Invasion!

Posted: Tue May 15, 2018 3:10 pm
by Batspiderfish
Brachymyrmex depilis is a pretty docile native species which occupies a different ecological niche from the surface-foraging Lasius (the subterranean aphid-farming species being a minor exception). I imagine that there is something about your yard which favors Brachymyrmex over Lasius, since these two genera have coexisted in North America for a very long time. What you are observing is how habitat loss can facilitate the displacement of native species by allowing another one to thrive. Solenopsis invicta would never have spread across the southern US if the forests were not cut down and replace with irrigated lawns and farms.

It's also worth noting that polygyny is only situationally advantageous over monogyny. A colony's size will always be limited by the amount of food that workers can bring in, and under similar circumstances, a colony with one queen may easily produce as much brood as does a colony with multiple queens. Having multiple queens can be genetically advantageous when you are competing with multiple nearby colonies of the same species (since your colony is able to produce more workers, faster, after the nuptial flight) but the caveat is that it is more difficult to spread your own genes when you are sharing resources with other queens. Monogynous colonies thrive in environments that face minimal competition from other ants of the same species.

Re: Brachymyrmex depilis Invasion!

Posted: Wed May 16, 2018 5:19 am
by antnest8
wow

Re: Brachymyrmex depilis Invasion!

Posted: Fri May 18, 2018 2:38 pm
by AntsDakota
Batspiderfish wrote:
Tue May 15, 2018 3:10 pm
Brachymyrmex depilis is a pretty docile native species which occupies a different ecological niche from the surface-foraging Lasius (the subterranean aphid-farming species being a minor exception). I imagine that there is something about your yard which favors Brachymyrmex over Lasius, since these two genera have coexisted in North America for a very long time. What you are observing is how habitat loss can facilitate the displacement of native species by allowing another one to thrive. Solenopsis invicta would never have spread across the southern US if the forests were not cut down and replace with irrigated lawns and farms.

It's also worth noting that polygyny is only situationally advantageous over monogyny. A colony's size will always be limited by the amount of food that workers can bring in, and under similar circumstances, a colony with one queen may easily produce as much brood as does a colony with multiple queens. Having multiple queens can be genetically advantageous when you are competing with multiple nearby colonies of the same species (since your colony is able to produce more workers, faster, after the nuptial flight) but the caveat is that it is more difficult to spread your own genes when you are sharing resources with other queens. Monogynous colonies thrive in environments that face minimal competition from other ants of the same species.
I think I have figured out why Brachymyrmex prefer my yard. My back yard only has a few inches of top soil, and then clay. I'll bet that ants have trouble digging through clay, and prefer dirt. I've noticed Brachymyrmex are fine nesting closer to the surface, so a few inches is fine for them. But Lasius prefer to dig deeper, so they probably prefer deeper soil. My front yard has more top soil than my back yard, so, as expected, there are more Lasius and less Brachymyrmex in my front yard than my back yard.