Adaptation to thermal stress in licheneating webspinners (Embioptera): habitat choice, domicile construction, and the potential role of heat shock proteins

Document Type

Article

Publication Date

4-2005

Publisher

British Ecological Society/John Wiley & Sons, Inc.

Abstract

Summary 1. Embiids are a unique group of web-spinning insects, which construct silk domiciles. In sunny habitats, silk may provide a shady refuge, or exacerbate exposure to high temperatures. Here we present the first description of the thermal biology of embiids, focusing on Notoligotoma hardyi from Magnetic Island, Australia. 2. We recorded natural colony positions and temperature of silk domiciles relative to incident radiation, and manipulated locations of domiciles on sunny (north-facing) and shady (south-facing) rock faces to test whether silk dampens thermal exposure. We also compared responses to laboratory heat stress in N. hardyi with two other embiids: Australembia incompta (Magnetic Island) and Antipaluria urichi (rainforest). 3. Temperatures of air (TA), rocks (TR) and domiciles (TD) are significantly hotter for north- than south-facing colonies. North-facing colonies have less extensive silk coverings and are found in crevices. For natural and experimentally manipulated north-facing colonies, TD was cooler than TR but hotter than TA, whereas TD and TA were similar for south-facing colonies. Individuals living in north-facing colonies adjusted position to remain in the shade. Ability to recover from heat exposure was greatest in Australian embiids and was linked to expression of heat shock proteins. 4. In sunny microhabitats, silk reduces but does not prevent exposure to physiologically stressful temperatures. N. hardyi tolerates thermal extremes using a combination of behavioural thermal regulation, microhabitat selection and a robust heat shock response.

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