Lab members and collaborators

O'Donnell Lab Research Projects

Prospective students can contact me (so356 "at" drexel.edu) for more information.

Current funding

Lead PI on Sponsored Research Agreement, Biologic Insecticides/Academic Venture Technologies, Developing erythritol as a novel human-safe insecticide (Daniel Marenda co-PI), 2017

Co-PI on Drexel Venture fund grant, Developing erythritol as a novel human-safe insecticide (Daniel Marenda PI), 2016

Co-PI on Wistar-Morris fund grant (awarded 2014, D. Velinsky PI): Using stable isotopes to test the role of nutrition in division of labor, 2014


The brief descriptions below present a sample of the active research projects in my lab.



Neotropical ants (Formicidae) experience a wide range of thermal environments: they forage and nest in diverse microhabitats from above- to below-ground, and some species span wide elevational ranges. We are exploring how these top predators respond to their thermal environments by measuring individual, colony, population and species differences in thermal physiology and social thermal homeostasis.


Nelson A.S., T.J. Scott, M. Barczyk, T. P. McGlynn, A. Avalos, E. Clifton, A. Das, A. Figueiredo, L. Figueroa, M. Janowiecki, S. Pahlke, J. Rana, and S.O'Donnell. In press. Day/night thermal tolerances differ within Ectatomma ruidum ant colonies. Insectes Sociaux.

Baudier, K.M. & S. O'Donnell. 2017. Weak links: How colonies counter the social costs of individual variation in thermal physiology. Current Opinion in Insect Science 22: 85-91. DOI 10.1016/j.cois.2017.06.004

Esch, C., J. Peña Jimenez, C. Peretz, H. Uno, & S. O'Donnell. 2017. Thermal tolerances differ between diurnal and nocturnal foragers in the ant Ectatomma ruidum. Insectes Sociaux. doi:10.1007/s00040-017-0555-x

Baudier K.M. & S. O'Donnell. 2016. Structure and thermal biology of subterranean army ant bivouacs in a tropical montane forest. Insectes Sociaux 63: 467-476.

Baudier K.M., A. E. Mudd, S.C. Erickson, & S. O'Donnell. 2015. Microhabitat and body size effects on heat tolerance: implications for responses to climate change (army ants: Formicidae, Ecitoninae). Journal of Animal Ecology 84: 1322-1330.

Soare, T.W., S.I. Tully, S.K. Willson, D.J.C. Kronauer & S. O'Donnell. 2011. Choice of nest site protects army ant colonies from environmental extremes in tropical montane forest. Insectes Sociaux 58: 299-308.

Kumar, A. & S. O'Donnell. 2009. Elevation and forest clearing effects on foraging differ between surface and subterranean army ants (Formicidae: Ecitoninae). Journal of Animal Ecology 78: 91-97.



Neuroecology: Evolution of brain architecture in social insects

We are using statistical methods that account for the effects of evolutionary relatedness (phylogeny) on correlated evolution among traits to test whether brain architecture has evolved along with social structure in paper wasps. Paper wasp phylogeny is well characterized at the genus level, and paper wasp exhibit a wide array of social complexities. Species vary in colony size, mode of colony founding, nest architecture, and in the degree of queen-worker caste differentiation. We are exploring how behavioral and developmental factors, such as nest architecture and caste determination, have affected the evolution of the amount of investment in functionally distinct brain regions. Brain size and female caste (queen vs. worker) are associated with brain structure differences.


O'Donnell, S. & S.J. Bulova. 2017. Development and evolution of brain allometry in wasps (Vespidae): Size, ecology and sociality. Current Opinion in Insect Science 22: 54-61. DOI 10.1016/j.cois.2017.05.014

Bulova S., K. Purce, P. Khodak, E. Sulger & S. O'Donnell. 2016. Into the black, and back: The ecology of brain investment in Neotropical army ants (Formicidae: Dorylinae). Science of Nature/Naturwissenschaften 103: 1-11.

O'Donnell S., S.J. Bulova, S. DeLeon, P. Khodak, S. Miller, & E. Sulger. 2015. Distributed cognition and social brains: reductions in mushroom body investment accompanied the origins of sociality in wasps (Hymenoptera: Vespidae). Proceedings of the Royal Society B 282: 20150791.

Sulger, E., N. Mcaloon, S.J. Bulova, J. Sapp & S. O'Donnell. 2014. Evidence for adaptive brain tissue reduction in obligate social parasites (Polyergus mexicanus) relative to their hosts (Formica fusca). Biological Journal of the Linnean Society 113: 415-422.

O'Donnell S., M.R. Clifford, S. DeLeon, C. Papa, N. Zahedi & S.J. Bulova. 2013. Brain size and visual environment predict species differences in paperwasp sensory processing brain regions (Hymenoptera: Vespidae, Polistinae). Brain Behavior and Evolution 82: 177-184.

O'Donnell, S., M.R. Clifford, & Y. Molina. 2011. A comparative analysis of constraints and caste differences in brain investment among social paper wasps. Proceedings of the National Academy of Sciences 108: 7107-7112.

Molina, Y., Harris, R. & S. O'Donnell. 2009. Brain organization mirrors the evolution of caste determination, colony founding and nest architecture in paper wasps (Hymenoptera: Vespidae). Proceedings of the Royal Society B 276: 3345-3351.


Individual and caste differences in brain architecture

The main goal of this project is to assess whether neural plasticity in the brain, particularly in the mushroom bodies, plays a functional role in social wasp workers' task performance. In addition to measuring gross brain region volumes, We use stereological microscopy techniques to measure the volume of functionally distinct regions of paper wasp brains, and test whether the size of different brain regions corresponds to individual differences in age, social rank, and task performance. We use Golgi staining methods to quantify changes in dendritic processes of brain neurons that may underlie changes in neuropil volume.


O'Donnell, S., S.J. Bulova, S. DeLeon, M. Barrett, & K. Fiocca. 2017. Caste-differences in the mushroom bodies of swarm-founding paperwasps: implications for brain plasticity and brain evolution (Vespidae, Epiponini). Behavioral Ecology and Sociobiology 71: 116.

Rehan S.M, S.J. Bulova, & S. O'Donnell. 2015. Cumulative effects of foraging behavior and social dominance on brain development in a facultatively social bee (Ceratina australensis). Brain, Behavior and Evolution 85: 117-124.

O'Donnell S., M.R. Clifford, S. Deleon, C. Papa, N. Zahedi & S.J. Bulova. 2014. A test of neuroecological predictions using paperwasp caste differences in brain structure (Hymenoptera: Vespidae). Behavioral Ecology & Sociobiology 68: 529-536.

Jones, T.A., N.A. Donlan & S. O'Donnell. 2009. Growth and pruning of mushroom body Kenyon cell dendrites during worker behavioral development in the paper wasp, Polybia aequatorialis (Hymenoptera: Vespidae). Neurobiology of Learning and Memory 92: 485-495 and Journal cover.

Molina, Y. & S. O'Donnell. 2007. Mushroom body volume is related to social aggression and ovary development in the paper wasp Polistes instabilis. Brain Behavior and Evolution 70: 137-144.

O'Donnell, S., N.A. Donlan, & T.A. Jones. 2007. Developmental and dominance-associated differences in mushroom body structure in the paper wasp Mischocyttarus mastigophorus. Developmental Neurobiology 67: 39-46.

O'Donnell, S., N.A. Donlan, & T.A. Jones. 2004. Mushroom body structural plasticity is associated with temporal polyethism in eusocial wasp workers. Neuroscience Letters 356: 159-162




Role of dominance interactions in regulating task performance in social insect colonies

Dominance is based on aggressive social interactions that influence individuals' access to resources. It has long been recognized that dominance among female social wasps plays a role in governing the separation between reproductive roles (queens) and sterile, helping roles (workers). I am working on several genera of independent-founding (Polistes and Mischocyttarus) and swarm-founding (Polybia) social wasps to assess how dominance interactions within the worker force influence task performance and non-reproductive division of labor (polyethism). I am particularly interested in the role of adult nutrition in governing social roles.


Smith, A.R., K.M. Kapheim, S. O'Donnell & W.T. Wcislo. 2009. Social competition but not subfertility leads to a division of labour in the facultatively social sweat bee Megalopta genalis (Hymenoptera: Halictidae). Animal Behaviour 78: 1043-1050. Featured in the In Focus section of journal.

Molina, Y. & S. O'Donnell. 2009. Worker reproductive competition affects division of labour in a primitively social paperwasp (Polistes instabilis). Insectes Sociaux 56: 14-20.

Molina, Y. & S. O'Donnell. 2009.Males exhibit novel relationships of dominance with nest departure in the social paper wasp Mischocyttarus mastigophorus (Hymenoptera: Vespidae). Ethology 115: 738-746.

Molina, Y. & S. O'Donnell. 2008. A developmental test of the dominance-nutrition hypothesis: Linking adult feeding, aggression, and reproductive potential in the paperwasp Mischocyttarus mastigophorus. Ethology, Ecology & Evolution 20: 125-139.

O'Donnell, S. 2006. Polybia wasp biting interactions recruit foragers following experimental worker removals. Animal Behaviour 71: 709-715.

O'Donnell, S. 2001. Worker biting interactions and task performance in a swarm-founding eusocial wasp (Polybia occidentalis, Hymenoptera: Vespidae). Behavioral Ecology 12: 353-359.

Markiewicz, D.A. & S. O'Donnell. 2001. Social dominance, task performance and nutrition: implications for reproduction in eusocial wasps. Journal of Comparative Physiology A 187: 327-333.




Behavior and ecology of army ants: how climate, elevation, and habitat alteration affect the biology of these top predators

Collaborators: Mike Kaspari (Univ. of Oklahoma), Anjali Kumar (AAAS fellow), John Lattke (Univ. Central de Venezuela), Scott Powell (George Washington University)

Army ants (Ecitoninae) are mobile insect societies that conduct mass hunting raids across and under forest leaf litter. They are top predators, and as such likely have an major impact on forest animal community structure. Army ants are akin to such spectacular elements of the Neotropical fauna as jaguars and harpy eagles. We have compared army ant community structure across latitudinal and elevational gradients to assess factors that affect their density, diversity, and ecological impact on prey and commensals. Results from this work suggest that army ant raids occur at astoundingly high rates in lowland primary wet forests, on the order of one raid/square meter/day! Our main approach has been to sample army ant density and diversity at different sites using standardized sampling protocols. By comparing latitudinally separate sites, we showed that army ant species composition changes significantly over regional scales, with implications for their commensals and parasites, including antbirds. Surveys across elevational gradients showed that above ground raiders and subterranean species differ in their responses to forest clearing and elevation.


O'Donnell S. & T. McGlynn. In press. Emigrating on the fly: a novel method of army ant colony movement observed in Eciton mexicanum. Journal of Insect Behavior. DOI: 10.1007/s10905-017-9635-z

Lukasik, P., J.A. Newton, J.G. Sanders, Y. Hu, C.S. Moreau, D.J.C. Kronauer, S. O'Donnell, R. Koga, & J.A. Russell. 2017. The structured diversity of specialized gut symbionts of the New World army ants. Molecular Ecology. 26: 3808-3825. DOI: 10.1111/mec.14140

Kaspari, M., S. Powell, J. Lattke, & S. O'Donnell. 2011. Predation and patchiness in the tropical litter: do swarm-raiding army ants skim the cream or drain the bottle? Journal of Animal Ecology 80: 818-823.

O'Donnell, S., M. Kaspari, A. Kumar, J. Lattke & S. Powell. 2011. Elevational and geographic variation in army ant swarm raid rates. Insectes Sociaux 58: 293-298.

O'Donnell, S., J. Lattke, S. Powell & M. Kaspari. 2009. Species and site differences in Neotropical army ant emigration behavior. Ecological Entomology 34: 476-482.

O'Donnell, S., J. Lattke, S. Powell, & M. Kaspari. 2007. Army ants in four forests: Geographic variation in raid rates and species abundance. Journal of Animal Ecology 76: 580-589.

O'Donnell, S. & A. Kumar. 2006. Elevational patterns of army ant community composition in tropical montane forest. Ecological Entomology 31: 491-498.

Kaspari, M. & S. O'Donnell. 2003. High rates of army ant raids in the Neotropics and implications for ant colony and community structure. Evolutionary Ecology Research 5: 933-939.



Analyzing how communication affects task allocation

Collaborators: Dr. Susan Bulova, Dr. Michael O'Connor

A review of the role of social communication in allocating workers among tasks showed that social insects employ diverse modes of communication to coordinate labor with their colonies. The details of these communicative mechanisms, of the structure of social groups, and of worker responses to social information may all shape the ways that colonies allocate workers among different jobs. We developed an individual-based simulation model to explore how characteristics of social groups (number of group members), details of communicative interactions (the strength of effects on receivers), and cognitive mechanisms (forgetting about past interactions) can influence the recruitment of group members to a new task.


O'Connor, M.P. & S. O'Donnell. 2017. Implications of iterative communication for biological system performance. Journal of Theoretical Biology 436: 93-104.

O'Donnell, S. & S.J. Bulova. 2007. Worker connectivity: a review of the design of worker communication systems and their effects on task performance in insect societies. Insectes Sociaux 54: 203-210.

O'Donnell, S. & S.J. Bulova. 2007. Worker connectivity: a simulation model of variation in worker communication and its effects on task performance. Insectes Sociaux 54: 211-218.




Elevational and seasonal patterns of species richness and community composition in Neotropical paper wasps (Vespidae) in tropical dry forest

Collaborators and students: Dr. Daniel Janzen (Univ. of Pennsylvania), Josephine Rodriguez (Univ. of Illinois Entomology PhD student), Sean Tully (BS, Univ. of Washington Psychology)

We will replicate the ALAS study with malaise trap samples collected at various elevations on the slopes of Cacao Volcano and in the Santa Rosa sector of the Guanacaste Conservation Area. This study will add an important seasonal component to the data, allowing us to test for temporal changes in tropical paper wasp community composition.


O'Donnell, S., & J.H. Hunt. 2013. Group hunting by two species of Neotropical swarm-founding paper wasps (Parachartergus apicalis and Agelaia sp., Hymenoptera: Vespidae). Insectes Sociaux 60: 369-372.

Kumar, A., J.T. Longino, R.K. Colwell & S. O'Donnell. 2009. Elevational patterns of diversity and abundance of eusocial paper wasps (Vespidae) in Costa Rica. Biotropica 41: 338-346.



Population genetics of Neotropical army ants (Ecitoninae)

Collaborators and students: Dr. Anjali Kumar (AAAS fellow), Dr. Kerry Naish (Univ. of Washington Aquatic & Fishery Sciences), Tom Soare (Univ. of Washington Animal Behavior PhD student)

Our behavioral and ecological data show that army ants can be affected by changes in elevation, and by human disturbances such as forest clearing and forest fragmentation. Temperature and other abiotic gradients appear to play a strong role in army ant distributions and movement patterns. However, army ant species differ in their responses to habitat variation. We are particularly interested in differences between above-ground raiding species (Eciton burchellii) and underground raiding species (Labidus coecus). We are scoring both nuclear (microsatellites) and mitochondrial DNA markers of genetic variability to quantify population genetic structure in army ants, with the aim of identifying ecological variables that affect population genetic structure. The microsatellite data, which include both maternal and paternal contributions to colony genetics, will complement the patterns seen in the maternally inherited mtDNA markers. Maternal inheritance patterns may be especially relevant in these ants: they have wingless queens, and colonies reproduce by splitting the work force, part of which literally walks away with a new queen. Males are winged and potentially move genes over longer distances. Our microsatellite data confirm that army ant queens have very high mating frequencies.


Soare, T.W., A. Kumar, K.A. Naish & S. O'Donnell. 2014. Genetic evidence for habitat effects on colony dispersal in the army ant Eciton burchellii. Molecular Ecology 23: 96-109.



Habitat variation effects on birds attending army ant raids in tropical montane forests and Bivouac checking by birds that attend army ant raids

Collaborators: Nicole Arcilla, Nicola Clayton (Cambridge University), Anjali Kumar (AAAS fellow)

A diverse fauna of birds attend army ant raids in montane tropical forests. The birds obtain food at the swarm raids by capturing small animals that flee from the advancing army ants. The montane attendants are particularly interesting because few or no true antbirds are present in montane forests. We are exploring the possibility that high-fidelity or obligate ant following behavior has evolved in some montane bird species. Montane army ant following birds are affected by elevation and forest fragmentation.

Among the birds that attend montane army ant raids are several species of long-distance migrants that breed in North America. These include species of thrushes, warblers and vireos. We are using relative abundance estimates from previous mist net studies to assess whether some migrants are specialized as army ant followers.

Some birds that specialize as army ant followers engage in elaborate behavior called bivouac checking. These birds visit the temporary resting clusters of a series of army ant colonies in the early morning, apparently assessing the ant's raid activity for that day. We are interested in the expression of this behavior by some montane birds that are not in the true antbird family (Thamnophilidae). We are also interested in the cognitive implications and challenges of bivouac checking for the birds.


O'Donnell, S. 2017. Evidence for facilitation among avian army-ant attendants: specialization and species associations across elevations. Biotropica. DOI: 10.1111/btp.12452

Driver R.W., S.D. DeLeon, & S. O'Donnell. In press. Novel observation of a raptor (Collared Forest-falcon: Micrastur semitorquatus) predating a fleeing snake (Squamata: Serpentina) at an army ant raid front (Eciton burchellii parvispinum). Wilson Journal of Ornithology.

Arcilla N., L.H. Hollbech, & S. O'Donnell. 2015. Severe declines of understory birds follow illegal logging in Upper Guinea forests of Ghana, West Africa. Biological Conservation 188: 41-49.

O'Donnell, S., A. Kumar & C.J. Logan. 2014. Do Nearctic migrant birds compete with residents at army ant raids? A geographical and seasonal analysis. Wilson Journal of Ornithology 126: 474-487.

O'Donnell, S., C.J. Logan & N.S. Clayton. 2012. Specializations of birds that attend army ant raids: an ecological approach to cognitive and behavioral studies. Behavioural Processes 91: 267-274.

Logan, C., S. O'Donnell, & N. Clayton. 2011. A case of mental time travel in ant-following birds? Behavioral Ecology 22: 1149-1153.

O'Donnell, S., A. Kumar & C. Logan. 2010. Army ant raid attendance and bivouac-checking behavior by Neotropical montane forest birds. Wilson Journal of Ornithology 122: 503-512.

Kumar, A. & S. O'Donnell. 2007. Fragmentation and elevation effects on bird-army ant interactions in Neotropical montane forest of Costa Rica. Journal of Tropical Ecology 23: 581-590.


 Predation on paper wasps by Red-throated Caracaras

Collaborator: Sean McCann (Simon Fraser Univ. Biological Sciences PhD student)

I am collaborating with Sean on part of his thesis work on these amazing birds. Red-throated Caracaras appear to rely heavily on the nests of paper wasps as prey items. We are analyzing video tapes of nestling feedings by a group of adults to identify which genera of paper wasps are collected by the adults.


McCann S., T. Jones, O. Moeri, C. Scott, S. O'Donnell & G. Gries. 2015. Red-throated Caracara, a falconid raptor, rivals predatory impact of army ants on social wasps. Insectes Sociaux 62: 101-108.

McCann S., O. Moeri, T. Jones, C. Scott, G. Khaskin, R. Gries, S. O'Donnell, & G. Gries. 2013. Strike fast, strike hard: the Red-throated Caracara exploits absconding behavior of social wasps during nest predation. PLOS ONE 8: e84114.

McCann, S., O. Moeri, T. Jones, S. O'Donnell & G. Gries. 2010. Nesting and nest provisioning of the Red-throated Caracara (Ictyber americanus). Journal of Raptor Research 44: 236-240.