Distinguishing symbiotic partners of Acropyga ants from free-living soil inhabitants

Authors: Schneider, Scott; SODANO, JAMES - TOWSON UNIVERSITY; LAPOLLA, JOHN - TOWSON UNIVERSITY

Submitted to: Neotropical Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/31/2022
Publication Date: 2/9/2022
Citation: Schneider, S.A., Sodano, J., Lapolla, J.S. 2022. Distinguishing symbiotic partners of Acropyga ants from free-living soil inhabitants. Neotropical Entomology. 2022. https://doi.org/10.1007/s13744-022-00948-9.
DOI: https://doi.org/10.1007/s13744-022-00948-9

Interpretive Summary: Partnerships between ants and scale insects serve as important model systems for understanding the evolutionary processes underlying mutualisms. These relationships are analogous to the herding of livestock and are often discussed in comparison to human agricultural practices. Natural history collections from the field are the foundation upon which our knowledge about mutualisms is built. It is therefore critical to use field collection techniques that give accurate information about species-to-species relationships for downstream application in research. This article describes a protocol for collecting subterranean ants and associated scale insects, which relies upon the activity of worker ants to sort their partners and distinguish them from other soil-dwelling species that may live near the ant colony but are not directly associated with it. Application of this protocol helps collectors avoid misrepresenting relationships between species in the published record and provides other useful natural history and behavioral information. We also describe the construction of simple nest-boxes, which have broad application in the study of ant colonies and their behavior. This protocol is of value to scientists who research symbioses or systematists who research ant and scale insect taxa involved in these types of relationships.

Technical Abstract: The fruitful study of associations between ants and scale insects yields insight into the mechanisms that shape these symbioses. Field collections provide the basic information linking partnered species, and as such it is critical that collection techniques from the field reflect true species-to-species partnerships in the published literature. It is equally critical that such practices limit the potential for mistaking free-living “neighbors” for symbiotic partners and publishing erroneous associations. This article describes a protocol for collecting subterranean scale insects and associated Acropyga ants, which relies upon the activity of worker ants to sort and distinguish symbionts from free-living scale insects that happen to live near the colony. By collecting samples of ants and scales into nest-boxes and allowing a resting period of several hours, worker ants will gather symbiotic partners into dense, protected clusters in which symbionts are actively tended. Free-living scale insects neighboring the colony can be collected from soil along with colony samples, but these free-living individuals are excluded from protective clusters and ignored by workers. Following confirmation of ant-attendance, true symbiotic partners can be confidently collected, preserved, and recorded for future study. We illustrate the value of employing this collection protocol using a case study from Peru.