Distinguishing Symbiotic Partners of Acropyga Ants from Free-Living Soil Inhabitants

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 Roger 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.