Light level as an environmental cue for foraging in Red Harvester AntsZoe Henrichs & Matt Brown

Test Organism

Pogonomyrmex barbatus

Purpose & Hypothesis • Investigation into the environmental cues influencing foraging

behaviour and activity. • To test light level as foraging inducer• Hypothesized most activity would be seen in starved ants

under brightest light.

Materials & Methods • Ants kept under 24-hour dark cycle.• Red light used as control• Timed ants dispersal to the other end of chamber under

varying light intensities• 10 trials at every intensity, 5 minute limit

Results Mean time of starved vs. non-starved groups at varying light intensities

Red Light 25 Watts 40 Watts 60 Watts 100 Watts

0

50

100

150

200

250

300

Non-StarvedStarved

Light Intensity in Watts

Tim

e (s

)

Results

Red Light 25 Watts 40 Watts 60 Watts 100 Watts0

50

100

150

200

250

300

Light Intensity

Tim

e (s

)

General Expectation

Starved vs Non-starved

195

200

205

210

215

220

225

230

235

240

Tim

e (s

)

Non starved Starved

Discussion

• Results contradicted hypothesis (Denebourgh, Depickere and Fresneau 2004)

• Slower mean times at high light intensity• No even distribution of results

• Overlap in SD• Variance of results• Small sample number

Discussion

• Ways to improve future studies• Control temperatures (Cole et al 2013)

• Separate brood-tenders and foragers (Deneubourg, Depikere and Fresneau 2005)

• Stimulation - trail laying and interaction (Bala et al 2013)

• Many unknowns• Effects of environmental cues aren’t widely studied• Climate change and preservation

Time to complete trial (red vs normal light)

Red Light Normal Light 0

50

100

150

200

250

300

Tim

e (s

)

% failing to complete the trial

Red Light 25 Watt 40 Watt 60 Watt 100 Watt0.00%

10.00%

20.00%

30.00%

40.00%

50.00%

60.00%

70.00%

80.00%

90.00%

100.00%

Prop

ortio

n

ReferencesBala A, Gordon D, Holmes S, Merrell A, Stumpe M, Queirolo J, Pinter-Wollman N. 2013. Harvester ants use interactions to regulate forager activation and availability. Animal Behavior. 86.197-207 Cole B, Huber Z, Smith A, Wiernasz D. 2009. The structure of foraging activity in colonies of the harvester ant, Pogonomyrmex occidentalis. Behavioral Ecology. 21. 337-342. Deneubourg J., Detrain C., Mailleux A. 2005. Triggering and persistence of trail-laying in foragers of the ant Lasius niger. Journal of Insect Physiology. 51. 297-304. Deneubourg J., Depickere S., Fresneau D. 2004. The influence of red light on the aggregation of the ant Lasius niger. Journal of Insect Physiology. 50. 629-635. Gordon D. 2001. Ants at work: how an insect society is organized. Philosophy of Science. 68. 268-270. Hemmi J, Narendra A, Reid S. 2010. The twilight zone: ambient light levels trigger activity in primitive ants. Royal Society B: Biological Sciences. 227: 1531-1538.

ReferencesHobbs R.J. 1985. Harvester ant foraging and plant species distribution in annual grassland. Oecologia. 67. 519-523. Ingram K, Kleeman L, Peteru S. 2011. Differential regulation of the foraging gene associated with task behaviors in harvester ants. BMC Ecology. 11. 19. Jayatilaka P, Narendra A, Radershall C, Zeil J. 1994. Individual foraging patterns of the jack jumper ant Myrmecia croslandi (Hymenoptera: Formicidae). Myrmecological News. 19. 75-83. Rosengren R., Fortelius W. 1986 Light : dark induced activity rhythms in Formica ants (Hymenoptera: Formicidae). Entomol. Gener. 11, 221–228. Ruano F, Soler J, Tinaut A. 1999. High surface temperatures select for individual foraging in ants. Behavioral Ecology. 11. 396-404. Traniello, J. 1989: Foraging strategies of ants. Annual review of Entomology. 34: 191-210