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Keywords:

  • Behavioural thermoregulation;
  • Embiidina;
  • heat shock protein

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.