Subterranean Behavior and Other Notes for Ironoquia plattensis (Trichoptera: Limnephilidae) in Nebraska

Abstract

Ironoquia plattensis Alexander & Whiles (Triehoptera: Limnephilidae) was discovered along the Platte River in central Nebraska in tbe late 1990s, and basic information about its life history is not well understood. Here, we describe previously undocumented Hfe-history traits that demonstrate strategies used by I. plattensis for surviving in fluctuating wetland environments in a landscape formally shaped by flooding. In an off-channel aquatic habitat along the Platte River, we observed 1 ) larvae residing in a slough that did not dry completely, 2) larvae emigrating from aquatic to terrestrial habitats 1 mo earlier than reported previously, 3) larvae moving above ground during the summer aestivation period, 4) larvae residing underground in soil during summer aestivation, and 5) mass emergence and swarming of adults after daybreak in autumn. Underground larval aestivation represents a previously undocumented behavior for this species. It is unclear whether aestivating underground represents an unreported common behavior or an infrequent response to local disturbances.

Effects of cattle grazing on Platte River caddisflies (Ironoquia plattensis) in central Nebraska

“…The slough segment we examined had flowing water all year, except in the uppermost 30 m (Geluso et al 2011). Its deep-channel morphology and proximity to groundwater caused it to have longer periods of inundation than other sloughs on Shoemaker and adjacent Mormon Island (Harner and Whited 2011).…”

“…Slough banks were 25 to 50 cm high, the wetted channel perimeter ranged from 65 to 150 cm, and maximum water depth ranged from 6 to 17 cm along the section of slough where I. plattensis larvae were present (27 April 2010; 6 cross-sections measured at 50-m intervals). Water temperature averaged 11 6 1uC (SD), with pH = 7.8 6 0.1, conductivity = 1047 6 33 mS/cm, and dissolved O 2 = 6.6 6 1.4 mg/L (sampled from 6 cross-sections on 27 April 2010) (Geluso et al 2011). The Platte River caddisfly was first observed in this slough in May 2003 (Geluso et al 2011), and the slough supported among the greatest densities of the Platte River caddisfly known (Vivian 2010, Geluso et al 2011.…”

“…Water temperature averaged 11 6 1uC (SD), with pH = 7.8 6 0.1, conductivity = 1047 6 33 mS/cm, and dissolved O 2 = 6.6 6 1.4 mg/L (sampled from 6 cross-sections on 27 April 2010) (Geluso et al 2011). The Platte River caddisfly was first observed in this slough in May 2003 (Geluso et al 2011), and the slough supported among the greatest densities of the Platte River caddisfly known (Vivian 2010, Geluso et al 2011.…”

“…In subsequent surveys, it was observed in isolated wetlands along a 320-km reach of the Platte River from Lincoln County to Merrick County (Vivian 2010). The Platte River caddisfly develops in sloughs through 5 larval instars from autumn to spring, but unlike most caddisflies, larval I. plattensis emigrate from aquatic to terrestrial habitats in spring to aestivate for summer and then pupate in autumn (Whiles et al 1999, Geluso et al 2011. The terrestrial phase of its life cycle coincides with periods when off-channel aquatic habitats, especially sloughs, dry or have intermittent flow (Whiles et al 1999).…”

“…Specific habitat requirements and potential threats to the Platte River caddisfly remain largely unknown. To date, only a few publications have been focused on the species (Whiles et al 1999, Alexander and Whiles 2000, Geluso et al 2011.…”