The Effects of Size, Sex, and Reproductive Condition on Thermal and Desiccation Stress in a Riparian Spider (Pirata Sedentarius, Araneae, Lycosidae)

Abstract

Within a species, physiological tolerances and thermoregulatory behaviors may vary among ontogenetic stages or between sexes. Such different tolerances can strongly affect the ecology and life history of a species. In a laboratory study, we tested the hypothesis that Pirata sedentarius Montgomery 1904 is differentially susceptible to thermal/desiccation stress by size and sex. As predicted, male adults were more susceptible to thermal/desiccation stress than females. Unexpectedly, however, juvenile spiders survived longer under thermal/desiccation stress than adults. Furthermore, female adults without egg sacs displayed a trend toward higher thermal/desiccation tolerance than females carrying egg sacs. These results suggest that for P. sedentarius, microhabitat preferences and/or thermoregulatory behaviors may change over the course of development, and may vary between sexes and between females with and without egg sacs.

Low river flow alters the biomass and population structure of a riparian predatory invertebrate

“…However, drying sites were dominated by smaller, juvenile spiders, with very few or no large spiders occurring. A strategy of depending on damp soil near the river to resist desiccation is used commonly in riparian spiders (Carico, 1973; DeVito & Formanowicz, 2003), and smaller spiders can presumably use smaller or deeper interstitial refuges and remain in contact with damp rocks for longer. In addition, desiccation mortality is likely to vary with body size, as body surface area to volume ratios alter (Willmer, Stone & Johnston, 2000), with smaller spiders often surviving longer than adults (DeVito & Formanowicz, 2003).…”

Argiope bruennichi shows a drinking-like behaviour in web hub decorations (Araneae, Araneidae)

“…Since overheating of the spider body results in higher water losses (Davies and Edney 1952;DeVito and Formanowicz 2003), various behavioural traits reducing sun exposure will reduce or prevent water evaporation (Tolbert 1979;Humphreys 1993). These traits include the selection of microhabitats for appropriate web sites, the orientation of the web itself and the position of the spider in the web (Higgins and Ezcurra 1996), and the incorporation of web-based retreats (e.g.…”

Egg capsule architecture and siting in a leaf-curling sac spider, Clubiona riparia (Araneae: Clubionidae)

“…Desiccation is surely a problem for spiders and their eggs (Gillespie 1987;Hieber 1992;DeVito & Formanowicz 2003), and probably led to the evolution of known behavioral and architectural solutions (Humphreys 1975;Suter et al 1987;DeVito & Formanowicz 2003). We presume that capsule construction by C. riparia also serves to reduce desiccation, both of the spider and of its egg clutch.…”