Insectes Sociaux

, Volume 65, Issue 2, pp 233–239 | Cite as

Working in the rain? Why leaf-cutting ants stop foraging when it’s raining

  • A. G. Farji-BrenerEmail author
  • M. C. Dalton
  • U. Balza
  • A. Courtis
  • I. Lemus-Domínguez
  • R. Fernández-Hilario
  • D. Cáceres-Levi
Research Article


Understanding how environmental factors modulate foraging is key to recognizing the adaptive value of animal behavior, especially in ectothermic organisms such as ants. We experimentally analyzed the effect of rain on the foraging of leaf-cutting ants, a key ant group that is commonly found in rainy habitats. Specifically, we experimentally discriminate among direct and indirect effects of rain on laden ants and explore whether ants respond to rain predictors by incrementing their speed. Watered loads were frequently dropped although ants were not wet, and watered ants also dropped their loads although loads were not wet. Watered leaf fragments increased their weight by 143% and were dropped independently with regards to area or symmetry. Watering the trail did not affect the proportion of ants that dropped their loads. Ants increased their speed by 30% after experimental increments in relative humidity and the noise of raindrops on leaves near the trail. Our experimental results confirm earlier anecdotic evidence of the negative effect of rainfall on the foraging of leaf-cutting ants. We demonstrate that rain can strongly limit ant foraging through different mechanisms, affecting both the ant itself, and the maneuverability of laden ants, by increasing the weight of their loads. We also depict behavioral responses that may mitigate this negative effect on foraging: walking faster at signals of rainfall to reduce the portion of leaf fragments lost. Our results illustrate how environmental factors can directly and indirectly constrain ant foraging and highlight the relevance of behavioral responses to mitigate these effects.


Atta cephalotes Ant behavior Costa Rica Foraging Environmental restrictions 



This work was partially supported by the Fondo para la Investigación Científica y Tecnológica, Argentina (FONCYT; PICT 2015-1319) and CONICET, Argentina (PIP 2014–2016, 11220130100665-CO) to AFGB. The Organization for Tropical Studies (OTS) provided logistical support. One anonymous reviewer, Martin Burd and G. Pizzarello provided helpful comments on the manuscript.


  1. Alma A, Farji-Brener AG, Elizalde L (2016) Gone with the wind: short and long-term responses of leafcutter ants to the negative effect of wind. Behav Ecol 27:1017–1024CrossRefGoogle Scholar
  2. Bollazzi M, Roces F (2011) Information needs at the beginning of foraging: grass-cutting ants trade off load size for a faster return to the nest. PLoS One 6:e17667CrossRefPubMedPubMedCentralGoogle Scholar
  3. Branstetter MG, Ješovnik A, Sosa-Calvo J, Lloyd MW, Faircloth BC, Brady SG, Schultz T (2017) Dry habitats were crucibles of domestication in the evolution of agriculture in ants. Proc R Soc B 284(1852):20170095CrossRefPubMedPubMedCentralGoogle Scholar
  4. Bujan J, Yanoviak SP, Kaspari M (2016) Desiccation resistance in tropical insects: causes and mechanisms underlying variability in a Panama ant community. Ecol Evol 6:6282–6291CrossRefPubMedPubMedCentralGoogle Scholar
  5. Burd M, Howard JJ (2005) Global optimization from suboptimal parts: foraging sensu lato by leaf-cutting ants. Behav Ecol Sociobiol 59:234–242CrossRefGoogle Scholar
  6. Califano D, Chaves-Campos J (2011) Effect of trail pheromones and weather on the moving behavior of the army ant Eciton burchellii. Insectes Sociaux 58:309–315CrossRefGoogle Scholar
  7. Chown SL, Nicolson S (2004) Insect physiological ecology: mechanisms and patterns. Oxford University Press, OxfordCrossRefGoogle Scholar
  8. Esch C, Jimenez JP, Peretz C, Uno H, O’Donnell S (2017) Thermal tolerances differ between diurnal and nocturnal foragers in the ant Ectatomma ruidum. Insectes Sociaux. (online first) Google Scholar
  9. Farji-Brener AG, Elizalde L, Fernandez-Marín H, Amador-Vargas S (2016) Social life and sanitary risks: evolutionary and current ecological conditions determine waste management in leaf-cutting ants. Proc R Soc Ser B 283:20160625CrossRefGoogle Scholar
  10. Farji-Brener AG, Chinchilla F, Umaña M, Ocasio- Torres M, Chauta-Mellizo A, Acosta-Rojas D, Marinaro S, de Torres Curth M, Amador-Vargas S (2015) Branching angles reflect a tradeoff between reducing trail maintenance costs or travel distances in leaf-cutting ants. Ecology 96:510–517CrossRefPubMedGoogle Scholar
  11. Farji-Brener AG, Chinchilla F, Rikkin S, Sánchez-Cuervo AM, Triana E, Quiroga V, Giraldo P (2011) The “truck-driver” effect in leaf-cutting ants: how individual load influences the walking speed of nest-mates. Physiol Entomol 36:128–134CrossRefGoogle Scholar
  12. Farji Brener AG, Ruggiero A (1994). Leaf-cutting ants (Atta and Acromyrmex) inhabiting Argentina: patterns in species richness and geographical ranges sizes. J Biogeogr 21:535–543Google Scholar
  13. Hart AG, Anderson C, Ratnieks FL (2002) Task partitioning in leafcutting ants. Acta Ethol 5:1–11CrossRefGoogle Scholar
  14. Hodgson ES (1955) An ecological study of the behavior of the leaf-cutting ant Atta cephalotes. Ecology 36:293–304CrossRefGoogle Scholar
  15. Hölldobler B, Wilson EO (2011) The leafcutter ants: civilization by instinct. W. W. Norton, New YorkGoogle Scholar
  16. Jaffe K, Howse PE (1979) The mass recruitment system of the leaf cutting ant, Atta cephalotes (L.). Anim Behav 27:930–939CrossRefGoogle Scholar
  17. Krebs JR, Davies NB, Parr J (1993) An introduction to behavioral ecology. Blackwell Scientific Publications, CambridgeGoogle Scholar
  18. Lighton JR, Feener DH Jr (1989) Water-loss rate and cuticular permeability in foragers of the desert ant Pogonomyrmex rugosus. Physiol Zool 62:1232–1256CrossRefGoogle Scholar
  19. Kaspari M, Clay NA, Lucas J, Yanoviak SP, Kay A (2015) Thermal adaptation generates a diversity of thermal limits in a rainforest ant community. Glob Change Biol 21:1092–1102CrossRefGoogle Scholar
  20. Lighton JR, Bartholomew GA, Feener DH (1987) Energetics of locomotion and load carriage and a model of the energy cost of foraging in the leaf-cutting ant Atta colombica Guer. Physiol Zool 60:524–537CrossRefGoogle Scholar
  21. McDade LM, Bawa KS, Hespenheide HA, Hartshorn GS (eds) (1994) La Selva: ecology and natural history of a Neotropical rain forest. University of Chicago Press, ChicagoGoogle Scholar
  22. Moll K, Roces F, Federle W (2010) Foraging grass-cutting ants (Atta vollenweideri) maintain stability by balancing their loads with controlled head movements. J Comp Physiol A 196:471–480CrossRefGoogle Scholar
  23. Moll K, Roces F, Federle W (2013). How load-carrying ants avoid falling over: mechanical stability during foraging in Atta vollenweideri grass-cutting ants. PLoS One 8(1):e52816CrossRefPubMedPubMedCentralGoogle Scholar
  24. Mueller UG, Mikheyev AS, Hong E, Sen R, Warren DL, Solomon SE, Juenger TE. (2011) Evolution of cold-tolerant fungal symbionts permits winter fungiculture by leafcutter ants at the northern frontier of a tropical ant–fungus symbiosis. Proc Natl Acad Sci 108:4053–4056CrossRefPubMedPubMedCentralGoogle Scholar
  25. Porter SD, Tschinkel WR (1987) Foraging in Solenopsis invicta (Hymenoptera: Formicidae): effects of weather and season. Environ Entomol 16:802–808CrossRefGoogle Scholar
  26. Riley RG, Silverstein RM, Carroll B, Carroll R (1974) Methyl 4-methylpyrrole-2-carboxylate: a volatile trail pheromone from the leaf-cutting ant, Atta cephalotes. J Insect Physiol 20:651–654CrossRefPubMedGoogle Scholar
  27. Roces F, Kleineidam C (2000) Humidity preference for fungus culturing by workers of the leaf-cutting ant Atta sexdens rubropilosa. Insectes Soc 47:348–350CrossRefGoogle Scholar
  28. Roces F, Tautz J (2001) Ants are deaf. J Acoust Soc Am 109:3080–3082CrossRefPubMedGoogle Scholar
  29. Röschard J, Roces F (2002) The effect of load length, width and mass on transport rate in the grass-cutting ant Atta vollenweideri. Oecologia 131:319–324CrossRefPubMedGoogle Scholar
  30. Spicer ME, Stark AY, Adams BJ, Kneale R, Kaspari M, Yanoviak SP (2017) Thermal constraints on foraging of tropical canopy ants. Oecologia 183:1007–1017CrossRefPubMedGoogle Scholar
  31. Weber NA (1972) The fungus-culturing behavior of ants. Am Zool 12:577–587CrossRefGoogle Scholar
  32. Whitford WG, Ettershank G (1975) Factors affecting foraging activity in Chihuahuan desert harvester ants. Environ Entomol 4:689–696CrossRefGoogle Scholar
  33. Willis MA, Avondet JL (2005) Odor-modulated orientation in walking male cockroaches Periplaneta americana, and the effects of odor plumes of different structure. J Exp Biol 208:721–735CrossRefPubMedGoogle Scholar
  34. Wolf H, Wehner R (2005) Desert ants compensante for navigation uncertainity. J Exp Biol 208:4223–4230CrossRefPubMedGoogle Scholar

Copyright information

© International Union for the Study of Social Insects (IUSSI) 2018

Authors and Affiliations

  1. 1.Laboratorio Ecotono, INIBIOMA, Centro Regional Universitario BarilocheUniversidad del Comahue y CONICETBarilocheArgentina
  2. 2.Museo Argentino de Ciencias Naturales “Bernardino Rivadavia”-CONICETBuenos AiresArgentina
  3. 3.Centro Austral de Investigaciones Científicas (CADIC-CONICET)UshuaiaArgentina
  4. 4.Facultad de Ciencias Exactas y Naturales y AgrimensuraUniversidad Nacional del Nordeste-CONICETCorrientesArgentina
  5. 5.Instituto de Ecología A.C., Red de Biología EvolutivaVeracruzMexico
  6. 6.Herbario Forestal MOL, Universidad Nacional Agraria La MolinaLimaPeru
  7. 7.Facultad de Ingeniería AgrariaUniversidad Católica Sedes SapientiaeLos OlivosPeru

Personalised recommendations