Random walk modeling of adult Leuctra ferruginea (stonefly) dispersal

• Adult EPT insects are trapped within Philadelphia over a 1 year period.
• An individual based random walk model of stonefly flight behavior is developed.
• Levy flight behavior provided the best match for field observations.
• Model estimates suggest that the stonefly L. ferruginea may be dispersing actively.

Aquatic insects of the orders Ephemeroptera, Plecoptera and Trichoptera (EPT) are commonly used as indicators of freshwater quality. Recolonization of restored waterways by these pollution intolerant insects is frequently employed to measure the success of stream restoration efforts. Post restoration monitoring programs based on recolonization by EPT indicator species are typically generalized with little consideration for local conditions. Within Philadelphia urban development has resulted in a loss of unimpaired headwater streams that might serve as refugia of EPT colonists to replenish downstream populations through passive drift of larvae and ova. In this urban setting, recolonization may depend largely on overland flight by adults from other systems.In an attempt to predict the likelihood of overland dispersal by adult EPT within Philadelphia, PA, USA, a one year field study was conducted at the Schuylkill Center for Environmental Education (SCEE) in Northwest Philadelphia to obtain data on local EPT taxa and dispersal behavior. Adult EPT specimens belonging to 15 species were collected using sticky traps extending laterally from Meig's Run, a 1st order tributary to the Schuylkill River. Leuctra ferruginea (Plecoptera: Leuctridae) was selected as the study species.A random walk model was developed and calibrated to field observations to predict long distance dispersal probability. An individual-based Lévy flight random walk model provided the best fit for field observations from Meig's Run, as well as supporting observations and theory proposed in existing literature.