4 replies to this topic

[drtrmiller]

Disclaimer: The following is an anecdotal account from multiple observations.  I did not set up the experiment with the intention of testing a hypothesis, but am simply reporting what I have seen after noticing the issue described.

 

 

Over the past 2 months, I have been offering unlimited amounts of Sunburst Ant Nectar to a wild colony of Linepithema humile that enjoys entering my house through small cracks.  Based on the amount they are drinking each day, with no discernable reduction in feeding activity over these past months, the colony appears to be very large.

 

Over the past 10 days or so, I filled up 5 byFormica Mega liquid feeders with 40 mL of Sunburst Ant Nectar each (200 mL total), and placed the feeders in a single row for the ants to drink.  The liquid content and the feeder design is the same for each, so the only variable is the position of the feeder.  Each feeder is almost touching the other--there is not much distance between them in the row.

 

After 10 days, I measured the net amount of liquid remaining in each feeder, by weight.  Here are the results, from left to right in the row of 5 feeders:

 

 

The ants are tending the feeders different amounts, despite the contents of each being identical.  In total, I would estimate the ants are consuming 10-15 mL of fluid per day.  The feeding activity appears to vary based on the temperature and environmental conditions outside, as noted by the density of ants along the foraging trail.

 

I conclude that the position/placement of the feeder is distorting the rate of feeding.  Therefore, in future food studies, it may be necessary to frequently randomize the placement of feeders or foods when conducting comparison studies of the attractiveness of closely related foods in order to eliminate the possibility of position bias.  How to do this in a way where the foraging trails are not also intermingled so as to affect the results, I have no idea.

Edited by drtrmiller, April 25 2020 - 11:56 AM.

[VoidElecent]

I conclude that the position/placement of the feeder is distorting the rate of feeding. 

 

10-15 mL! Those are some thirsty ants! Out of curiosity, where are the feeders positioned relative to the nest entrance?

[drtrmiller]

 

I conclude that the position/placement of the feeder is distorting the rate of feeding. 

 

10-15 mL! Those are some thirsty ants! Out of curiosity, where are the feeders positioned relative to the nest entrance?

 

 

I have no idea where the nest is.  They're polydomal and relocate nests quite frequently. The foraging trail is about 10 feet long from the feeders to the crack in the wall where the ants are entering my house.  But I have no idea how far the foraging trail spans from that point to where queens and brood are nesting.  

 

As an aside, I had fun over the past few months moving the feeders farther and farther away to test if the ants would find a more efficient route entering through another area.  I've siliconed lots of little gaps in my drywall, which are common in bathrooms because of all the cutouts for showers, cabinets, and light switches, in order to reduce the points of entry.  But it's like whack-a-mole—every place I plug, they find a new way inside.

Edited by drtrmiller, April 25 2020 - 12:06 PM.

[BugFinder]

 

I conclude that the position/placement of the feeder is distorting the rate of feeding. 

 

10-15 mL! Those are some thirsty ants! Out of curiosity, where are the feeders positioned relative to the nest entrance?

 

Like Terry said, probably a massive colony.  Lots of mouths to feed.

[Serafine]

This may not even be a coherent thing but caused by more-or-less random chance - basically the feeders that get the most workers initially may get a stronger mark than the other ones and thus attract more workers.

The terrain surrounding the feeders and the layout of their trail may affect it further, as well the way the ants fan out when they hit the blob of ants surrounding the closest feeder (if the ants do in fact act like little robots and fan out for a rather consistent distance this could explain feeder #3 being mostly omitted (because of the blob in front of feeder #1 and #2) but then again it could just be random chance or any other factor).

 

I've observed positional bias even in my comparable small 60x30cm outworld, the feeders that are emptied the quickest seem to be the ones close to nest entrances and highly frequented areas (trails, crossroads).

Edited by Serafine, May 17 2020 - 4:15 AM.