Night owls or morning larks? Study of food retrieval by Solenopsis geminata ants
Abstract
Keywords: ant behaviour, circadian rhythm, foraging, light, temperature
INTRODUCTION
Background/Rationale
Description of Solenopsis geminata: Solenopsis geminata is a ubiquitous ant which is 3-5 mm long. The body is orangish brown and it has a brown head. These ants are highly invasive and are known to have the potential to devastate native ant populations. It presents a great threat to conservation values as it invades native communities. They respond aggressively by stinging to any disturbance caused to them. It usually thrives in hot arid regions. Cold climates are quite unsuitable for them. S. geminata prefers food with high protein content. The diet also includes many human foods rich in carbohydrates. The oldest ants in the colony are the foragers.
Objectives of the Research
Overall objective
1. To study and compare the foraging behaviour of Solenopsis geminata across different times during day and night.
2. To examine whether the foraging frequency is higher during the day or night.
3. To compare the individual components like transport velocity, frequency and duration of visit across day and night using statistical methods.
METHODOLOGY
Methods
Nests of Solenopsis geminata were located by providing a food source, observing their trails and tracing their path. Multiple nests were found.
Experiments were conducted to know the food preference of the ants.
Trial experiments were done to find out the exploratory distance (the distance range was kept constant).
0.82 grams of chocolate was provided at a distance of 40 cm - 60 cm.
Initial conditions like humidity and temperature were noted.
Times at which the first as well as successive ants arrived were recorded.
Duration that the ants spent at the food source and the time it reached back to its nest were noted down.
Walking velocity was calculated from the displacement between food and nest and the time it took to reach the nest from the food site.
Visit duration was computed from the visit time and departure time of each ant.
Number of ants coming out from the nest in a 15 minute window was noted down.
Above processes were carried out during day and night for different timings.
Data was analysed by non-parametric analysis using Mann-Whitney U test and have been presented using box plots.
Graphs were plotted between: 1. Velocity and visit duration
2. Velocity and visit time
3. Visit duration and visit time
4. Start time and velocity
And correlations between these components were studied.
LIMITATIONS:
1. During afternoon times, the chocolate often melted. It was difficult to discern whether the returning ants were unladen or carrying the melted chocolate towards the nest. (However, the working definition for our project was that if an ant spent more than 5 s at the food source before returning to the old nest, then it was considered a transporting ant)
2. Other species of ants were interfering with my ants of interest. This problem was tackled by keeping the food source in such a place where no other ant species’ nests were present.
3. Night observations were only made from 6:30-7:30 PM as compared to the day observations where the observation period ranged from 11 AM - 4 PM.
OBSERVATIONS
Day observations:
DAY 1 | |||||
31-05-2019 | 2:45 PM | ATREE | |||
30⁰ C | 48 cm(Distance from nest to food site) | ||||
SL.NO | VISIT TIME(min) | DEPARTURE TIME(min) | REACHES NEST(min) | VISIT DURATION(s) | VELOCITY(cm/s) |
1 | 02:52 | 03:00 | 04:40 | 8 | 0.48 |
2 | 03:03 | 03:12 | 04:56 | 9 | 0.5 |
3 | 03:15 | 03:21 | 05:15 | 6 | 0.43 |
4 | 03:41 | 03:49 | 05:30 | 8 | 0.51 |
DAY 2 | |||||
03-06-2019 | 2:30 PM | ATREE | |||
29⁰C | 52 cm(Distance from nest to food site) | ||||
SL.NO | VISIT TIME(min) | DEPARTURE TIME(min) | REACHES NEST(min) | VISIT DURATION(s) | VELOCITY(cm/s) |
1 | 02:34 | 03:28 | 04:00 | 54 | 0.72 |
2 | 02:49 | 03:57 | 04:56 | 68 | 0.88 |
3 | 02:52 | 04:02 | 05:10 | 70 | 0.76 |
4 | 02:56 | 04:09 | 05:17 | 73 | 0.76 |
5 | 02:59 | 04:12 | 05:28 | 73 | 0.68 |
6 | 03:02 | 04:25 | 05:34 | 83 | 0.75 |
7 | 03:07 | 04:30 | 05:48 | 83 | 0.60 |
8 | 03:10 | 04:36 | 06:02 | 86 | 0.60 |
DAY 3 | |||||
04-06-2019 | 3:45 PM | ATREE | |||
29⁰C | 49 cm(Distance from nest to food site) | ||||
SL.NO | VISIT TIME(min) | DEPARTURE TIME(min) | REACHES NEST(min) | VISIT DURATION(s) | VELOCITY(cm/s) |
1 | 01:30 | 02:25 | 03:02 | 55 | 1.36 |
2 | 01:54 | 02:41 | 03:21 | 47 | 1.22 |
3 | 02:02 | 02:56 | 04:01 | 54 | 0.75 |
4 | 02:15 | 03:24 | 04:21 | 69 | 0.87 |
5 | 02:40 | 03:52 | 04:56 | 72 | 0.76 |
6 | 03:12 | 04:04 | 05:10 | 52 | 0.74 |
7 | 03:30 | 04:25 | 05:32 | 55 | 0.79 |
8 | 03:45 | 04:40 | 05:55 | 55 | 0.66 |
9 | 04:12 | 05:25 | 06:38 | 73 | 0.68 |
10 | 04:15 | 05:32 | 06:56 | 77 | 0.58 |
DAY 4 | |||||
21-06-2019 | 2:30 PM | ATREE | |||
29⁰C | 57cm(Distance from nest to food site) | ||||
SL.NO | VISIT TIME(min) | DEPARTURE TIME(min) | REACHES NEST(min) | VISIT DURATION(s) | VELOCITY(cm/s) |
1 | 01:43 | 02:12 | 02:52 | 29 | 1.43 |
2 | 01:52 | 02:24 | 03:15 | 32 | 1.12 |
3 | 02:15 | 02:53 | 03:25 | 38 | 1.78 |
4 | 02:24 | 03:11 | 04:06 | 47 | 1.03 |
5 | 02:27 | 03:25 | 04:16 | 58 | 1.12 |
6 | 03:04 | 03:45 | 04:54 | 41 | 0.82 |
7 | 03:10 | 03:52 | 05:02 | 42 | 0.81 |
DAY 5 | |||||
28-06-2019 | 1:55 PM | ATREE | |||
30⁰C | 56 cm(Distance from nest to food site) | ||||
SL.NO | VISIT TIME(min) | DEPARTURE TIME(min) | REACHES NEST(min) | VISIT DURATION(s) | VELOCITY(cm/s) |
1 | 01:06 | 01:45 | 02:07 | 39 | 2.5 |
2 | 01:09 | 01:49 | 02:10 | 40 | 2.6 |
3 | 01:11 | 01:52 | 02:15 | 41 | 2.43 |
4 | 01:15 | 01:56 | 02:20 | 41 | 2.33 |
5 | 01:17 | 02:01 | 02:27 | 44 | 2.15 |
6 | 01:19 | 02:06 | 02:35 | 47 | 1.93 |
7 | 01:20 | 02:10 | 02:42 | 50 | 1.75 |
8 | 01:22 | 02:17 | 02:56 | 55 | 1.43 |
9 | 01:25 | 02:26 | 03:08 | 61 | 1.33 |
10 | 01:32 | 02:42 | 03:25 | 70 | 1.3 |
Night observations:
NIGHT 1 | |||
07-06-2019 | ATREE | 6:40 PM | |
25⁰C | 52 cm(Distance from nest to food site) | ||
NO ANTS |
NIGHT 2 | |||
ATREE | 7:00 PM | ||
25⁰C | 42 cm(Distance from nest to food site) | ||
NO ANTS |
NIGHT 3 | |||||
6:55 PM | ATREE | ||||
26⁰C | 54 cm(Distance from nest to food site) | ||||
SL.NO | VISIT TIME(min) | DEPARTURE TIME(min) | REACHES NEST(min) | VISIT DURATION(s) | VELOCITY(cm/s) |
1 | 03:58 | 04:20 | 06:15 | 22 | 0.46 |
2 | 06:20 | 06:57 | 08:07 | 37 | 0.77 |
NIGHT 4 | |||||
27-06-2019 | 7:10 PM | IASc FELLOWS RESIDENCY | |||
25⁰C | 45 cm(Distance from nest to food site) | ||||
SL.NO | VISIT TIME(min) | DEPARTURE TIME(min) | REACHES NEST(min) | VISIT DURATION(s) | VELOCITY(cm/s) |
1 | 05:01 | 06:14 | 07:50 | 73 | 0.46 |
2 | 05:58 | 06:49 | 08:04 | 51 | 0.6 |
3 | 06:25 | 07:19 | 08:28 | 54 | 0.65 |
4 | 06:52 | 07:51 | 09:00 | 59 | 0.65 |
5 | 07:35 | 08:12 | 10:32 | 37 | 0.32 |
6 | 08:10 | 09:22 | 11:01 | 72 | 0.45 |
NIGHT 5 | |||||
28-06-2019 | 7:15 PM | IASc FELLOWS RESIDENCY | |||
24⁰C | 53 cm(Distance from nest to food site) | ||||
SL.NO | VISIT TIME(min) | DEPARTURE TIME(min) | REACHES NEST(min) | VISIT DURATION(s) | VELOCITY(cm/s) |
1 | 03:50 | 04:17 | 05:10 | 27 | 1 |
2 | 03:58 | 04:28 | 05:21 | 30 | 1 |
3 | 04:02 | 04:32 | 05:29 | 30 | 0.92 |
4 | 04:09 | 04:36 | 05:40 | 27 | 0.82 |
5 | 04:13 | 04:42 | 05:47 | 29 | 0.81 |
Purpose
VISIT DURATION (DAY VS NIGHT)
The visit duration of Solenopsis geminata during day (51.41∓20.93s) is only marginally different from the visit duration during night (42.15∓17.63s; Mann-Whitney U test, N1 =39, N2 =13, U =167.5, p =0.07)
VELOCITY (DAY Vs NIGHT)
The transport velocity of Solenopsis geminata during day was found to be 1.12∓0.62 cm/s and this was significantly lower than the transport velocity during night (0.68∓0.22 cm/s; Mann-Whitney U test, N1=39, N2 = 13, U= 144, p=0.02)
FREQUENCY (DAY Vs NIGHT)
The number of ants coming out of the nest during day time for a 15 minute observation window (7.8∓2.48) was found to be higher as compared to night (2.6∓2.79; Mann-Whitney U test, N1=5, N2 = 5, U= 2, p=0.03)
CORRELATION
1. VELOCITY AND VISIT DURATION
No considerable correlation
2. VELOCITY AND VISIT TIME
There is a negative correlation between velocity and visit time.
3. VISIT DURATION AND VISIT TIME
No correlation observed
4. START TIME AND VELOCITY
A slight negative correlation is observed.
REMARKS:
1. On 07-06-2019, when food source was kept at two different distances during night, 52 cm (6:40 PM) and 42 cm (7:00 PM) respectively, no ants turned up. However, when the food source was kept at a distance of 15 cm (7:20 PM) from the nest, few ants came out.
Date: 07-06-2019
Temperature: 25 °C
Distance from the nest to the food source: 15 cm
Place: ATREE
2. On 27-06-2019, the night observation was done an hour after a slight drizzle.
CONCLUSION AND RECOMMENDATIONS
Conclusion
Changes in light intensities did affect the ground activity of Solenopsis geminata ants. Workers did not exhibit tendency to forage at night. Walking velocities of ants were relatively higher in day as compared to night. During night, ants walked much slower. This may be because their metabolic activity may be higher during day time (when the temperature is high). Also, the number of ants coming out of the nests were higher during day than in night. The frequency was very low or zero during night. Low temperature limited the ground activity. However, the visit duration of ants in both day and night was almost similar. They spent around same time on the food source on both times of the day. All these results were obtained in a short term study. Whether these results are consistent for longer periods and across different climatic conditions and long-term micro environmental factors remains to be investigated through future studies.
REFERENCES
1. G. C. Dibley, 1974
2.Walter R. Tschinkel, 1987
3. Traniello, et al, 1989
ACKNOWLEDGEMENTS
Foremost, I would like to express my sincere gratitude to my guide Dr. Priyadarsanan Dharma Rajan for his motivation and immense knowledge during my project.
Besides, I would like to thank Dr. Anoop Karunakaran. I could not have imagined having a better mentor for my study. I am grateful to him for enlightening me the first glance of research with his constant support, guidance, encouragement, insightful comments and enthusiasm.
I owe a lot to Dr. Seena Narayanan, Aswaj, Sneha and all lab members for being so cooperative and helpful.
I would also like to acknowledge the crucial role of IAS for selecting and enabling me to do the fellowship.
At last but not the least, huge thanks to my parents and sibling who were and are always there for me.
References
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Traniello, J F A (1989). Foraging Strategies of Ants. 34,
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T. Lewis, G. V. Pollard, G. C. Dibley, 1974, Rhythmic Foraging in the Leaf-Cutting Ant Atta cephalotes (L.) (Formicidae: Attini), The Journal of Animal Ecology, vol. 43, no. 1, pp. 129
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Sanford D. Porter, Walter R. Tschinkel, 1987, Foraging in Solenopsis invicta (Hymenoptera: Formicidae): Effects of Weather and Season, Environmental Entomology, vol. 16, no. 3, pp. 802-808
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