Ants adapt tool use to avoid drowning

Date:
October 8, 2020
Source:
British Ecological Society
Summary:
Researchers have observed black imported fire ants using sand to
draw liquid food out of containers, when faced with the risk of
drowning. This is the first time this sophisticated tool use has
been reported in animals.



FULL STORY ========================================================================== Researchers have observed black imported fire ants using sand to draw
liquid food out of containers, when faced with the risk of drowning. This
is the first time this sophisticated tool use has been reported in
animals. These findings are published in the British Ecological Society
journal Functional Ecology.


==========================================================================
A laboratory experiment has shown for the first time that a species of
ant has the remarkable ability to adapt its tool use. When provided with
small containers of sugar water, black imported fire ants were able to
float and feed on the surface, but when researchers reduced the surface tension, the ants started depositing sand grains on the inside of the
container leading out of it.

"We found the ants used sand to build a structure that could effectively
draw sugar water out of the container to then to be collected" said Dr
Aiming Zhou, an associate professor at Huazhong Agricultural University,
Wuhan, China, and a lead author of the research. "This exceptional tool
making skill not only reduced the drowning risk of ants, but also provided
a larger space for them to collect sugar water." The sand structures
were found to be so efficient that they could syphon almost half of the
sugar water out of the containers in five minutes.

Researchers altered the surface tension of the sugar water by adding surfactant. When surfactant concentrations were over 0.05%, representing considerable drowning risk, ants were observed building the sand
structures to syphon sugar water out of the container. These structures
were never observed when ants foraged in containers of pure sugar water, indicating an adaptable approach to this novel tool use.

The results not only demonstrate black imported fire ants' ability to use
tools to forage but also that they can recognise an increased foraging
risk and can adjust their tool use in response to this.

Dr Jian Chen, Research Entomologist at The U.S. Department of
Agriculture's (USDA) Agricultural Research Service (ARS), Stoneville Mississippi, and another author of the research, said: "We knew some
ant species are able to use tools, particularly in collecting liquid
food; however, we were surprised by such remarkable tool use displayed
by black imported fire ants. Our findings suggest that ants and other
social insects may have considerable high cognitive capabilities for
unique foraging strategies" Tool use is seen as an indicator of cognitive sophistication and has mostly been observed in primates and some species
of birds. But in invertebrates this behaviour is less well studied and
has previously been thought of as hard wired and inflexible.

Black imported fire ants, Solenopsis richteri, are native to South
America but are now an invasive species in southern United States after
being introduced.

Their Hydrophobic exoskeletons allow them to float on water but it's
likely that they still face frequent drowning risk in nature because of
the importance of liquid foods like nectar and honeydew as a carbohydrate source.

In the study the researchers calculated drowning risk by measuring the proportion of drowned ants in 2.5 cm containers of sugar water with
differing concentrations of surfactant. The ants were able to float
on the surface of pure sugar water, but the proportion of drowned ants increased significantly with increasing concentrations of surfactant. The researchers then provided ants with sands of varying grain size to test
their preferences in creating sand structures when faced with different drowning risks.

Dr Zhou cautions that further studies are needed in this research area,
saying: "Our experiments are conducted in the laboratory and only limited
to the black imported fire ants." The next steps will be to determine
how widespread this behavior is in other ant species. Dr Chen adds:
"Our study is the first to touch on this interesting topic. We hope our
paper will motivate others to do the related investigations."

========================================================================== Story Source: Materials provided by British_Ecological_Society. Note:
Content may be edited for style and length.


========================================================================== Related Multimedia:
*
Image_of_black_imported_fire_ants_using_sand_to_syphon_sugar_water_out_of
containers ========================================================================== Journal Reference:
1. Aiming Zhou, Yuzhe Du, Jian Chen. Ants adjust their tool use
strategy in
response to foraging risk. Functional Ecology, 2020; DOI:
10.1111/1365- 2435.13671 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2020/10/201008083807.htm

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