Over the past 2 weeks or so, I have been delineating the borders of a small Pheidole megacephala cluster at a fine level of detail.
The overall area covered by the species is around 1.1 ha, and I had been paying particular attention to the periphery of their control, where the density of P. megacephala drops off abruptly and a lot more ant species besides Brachymyrmex spp show up in baits.
My thinking is that it is only at the borders that I would be able to observe interesting interactions between the invasive ant and other species, and in fact I have already been an observer of a rare skirmish between the Pheidole megacephala and a Solenopsis invicta colony along one border area.
I found several interesting areas where future interactions between species might occur.
In one location, a line of shrubbery and trees formed a straight configuration that would easily allow me to determine clear borders for each species. By spreading cookie baits along the raised border on either side of the island, I was able to entice foragers to come out.
On the west side of the line of vegetation, I discovered that Pheidole megacephala controlled all the baits from the rightmost edge to the 6th bait, which was more than half the length of the island. I indicated this line of control with a blue double arrow (see image 1 below).
A small unidentified Pheidole sp (PH006) took control of the bait at #7, while a group of Solenopsis invicta fire ants mobbed the bait at #8. After one hour, I had yet to see any ants take over the bait at #9 or #10. Beyond #10, I placed four more bait mounds where the island curved. #11 and #12 both were controlled by the same small Pheidole sp PH006, while #14 was taken over by fire ants as well.
On the east side of the line of vegetation, I used the border between the concrete slabs of the pathway to determine areas of control. Baits were placed in the early morning and monitored after about an hour, and I used a drone pic from my DJI Mini 2 to view the area from above.
In the image above (see image 2), P. megacephala controlled baits #1-3 (on either side of the walking path), and the small unknown Pheidole sp. controlled baits #4-6 (black), with the exception of a Crematogaster sp at bait #8 (yellow). Integrating the data from both the west and east sides of the vegetation gives a good idea about the border between the P. megacephala and this small unknown Pheidole sp.
The proximity between these two species is interesting, and I have seen the same small Pheidole sp PH006 surviving slightly inside the periphery of the P. megacephala cluster at another point. Will this détente last?
It should be noted that P. megacephala tends to disappear as the morning progresses and the heat increases and humidity drops, so it would be interesting to see whether any other species takes control of baits placed between #1 and #6 later in the day. This line of vegetation also faces west, which means that the sun shines strongly on the area during the afternoon and guarantees that there will be almost no P. megacephala about.
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