Life histories of stoneflies (Plecoptera) in the Rio Conejos of southern Colorado

Abstract

Thirty-one stonefly species representing eight famihes were collected during the March 1987 to May 1990 study period. Genera represented by more than one species included Capnia. Utacapnia, Taenionema. Siiuallia, Triznaka, Isogenoides, and Isoperla. Peak species richness was recorded on or near the summer solstice in 1988 and 1989. Climatic differences between years were reflected in nymphal development and emergence phenology of most species. New or important corroborative life histoiy data are presented for 1 1 stonefly species of this assemblage. The hyporheic nymphal development of most chloroperlid species limited the number of early instars sampled and our capacity' to inteipret voltinism. Limited nymphal data suggested a univoltine-slow cycle for Phimiperia diversa (Prison). Adults of Suwallia pallidula (Banks) and S\ uardi (Banks) were present for an extended summer period, but the bulk of their respective emergence times was temporally separated. Isogenoides zionensis Hanson, Pteronarcella hadia (Hagen), and Pteronarcijs califomica Newport were all showTi for the first time to have a 9-10-mo egg diapause, and all three species have a semivoltine life cycle. Skwcda americana (Klapalek) and Isoperla ftdva Claassen were further confimied to have univoltine-slow cycles. Univoltine-fast and univoltine-slow life cycles are reported for the first time in /. phalerata and /. qiiinquepunctata, respectively. Regression analysis revealed that si.x of the eight abimdant species had extended emergence patterns (slopes of <5%/d), while only two had synchronous patterns. Warmer spring and summer temperatures in 1989 increased the slopes for five of the eight species studied, but did not change their synchrony designation.

Larval growth and development of the stonefly Pteronarcys californica (Insecta: Plecoptera) in the Crowsnest River, Alberta

“…Freilich (1991), who worked only with larvae with headcapsule widths of more than 3.0 mm, also reported a 3-year larval life in Pacific Creek, Wyoming. DeWalt and Stewart (1995) found a 9-to10-month egg stage and estimated a 38-month larval life, based on head-capsule widths, in the Rio Conejos, Colorado. Townsend and Pritchard (1999) showed that P. californica eggs from the Crowsnest River in southern Alberta took a minimum of 182 days (or >1790 day-degrees above the developmental zero (the intercept on the temperature axis of the linear regression of development rate on temperature)) for 50% hatch in the laboratory, with no observable development for approximately 80 d at any temperature.…”

Genetic evidence for cohort splitting in the merovoltine stoneflyPteronarcys californica(Newport) in Blacksmith Fork, Utah

“…In the Provo river, Utah, a four-year life cycle was estimated for P. californica (Branham and Hathaway 1975). DeWalt and Stewart (1995) also estimated a four-year life cycle in the Rio Conejos, Colorado. Given the variability in the duration of diapause reported by Pritchard and Townsend (2000) we predict that cohort splitting is common enough in P. californica to lead to little or no genetic differentiation among cohorts.…”

Environmental drivers influencing stonefly assemblages along a longitudinal gradient in karst lotic habitats

“…Most often, their emergence periods are synchronous and short, with different species emerging in temporal succession (Hynes, 1976;Zwick, 2011). Although many environmental factors influence emergence of aquatic insects, water temperature and photoperiod have been recognized as the most important for stonefly emergence (Hynes, 1976;Flannagan and Cobb, 1991;DeWalt and Stewart, 1995;Zwick, 2011;Ivković et al, 2014;.…”