Last weekend, I went backpacking near yosemite national park in california and I was fortunate to encounter 2 of my favorite ants from the area, Manica Bradleyi and Manica Invidia.
Not much of them is known in literature especially what they eat and their colony structure. I have always suspected bradleyi to be polygynous given that its relative Rubida is polygynous and bradleyi often has multiple "anthills" that can cover a relatively wide area.
The objectives of this study on the bradleyi colonies was mostly to explore more about their colony structure as well as their prey items so I could better understand how to keep them in captivity.
On previous excursions, I have observed a ~5-6 mm bradleyi worker attack and subdue a camponotus modoc minor of ~8-9mm that was nearly three times its size as well as carry off multiple dead formica fusca group workers to its nests. This led me to believe that they were specialists in ants, possibly subterranean brood raiders given that barely any ants were active.
However, I was lucky to encounter the colony in the morning where there were many ants active near the colony, I saw one bring back a spider leg as well as another one holding a dead termite which suggests that they may not subsist solely on other ants and partially refutes the idea that they are subterranean brood raiders as they seem to be more crepuscular in nature. That being said, I still think a large part of their diets is ants, as that is a niche with little competition.
I excavated a small part of a manica bradleyi colony to explore more about how the nest was structured. While I didn't encounter a queen, it does look like the nest is rather shallow which leads me to believe that manica colonies are structured wide and shallow although I am not too certain because the tunnels were small and well hidden, yet it didn't look like there was much of a swarm which happens when you even slightly disturb a tetramorium or formica colony.
While manica bradleyi was aggressive to formica and camponotus, it was passive towards other manica bradleyi 100 feet away suggesting that they may be part of the same colony or that they may just be passive ants all together as I've seen reports in literature of manica bradleyi acting peacefully with invidia. Similarly, they show initial aggression to aphaenogaster occidentalis, before letting go and disengaging and allowing the aphaenogaster to escape suggesting that their predation may be somewhat specialized or it could simply be that the aphaeno was able to escape from the manica's clutches.
In summary, my observations are rather inconclusive, but I do feel that they shed some light on an underappreciated species in california and could possibly be the closest equivalent to the iconic large ponerines such as neoponera, myrmecia, and ectamomyrmex available to us californians.
Edited by 11.11.00, August 3 2021 - 8:06 PM.
