2.1. Animals

Speckled cockroaches were purchased from Livefoods Unlimited (Adelaide, SA, Australia). They were maintained in a plastic container with a mesh lid, and the sides of the container were lined with Vaseline to prevent escape. Cockroaches were provided with dry cat food (Purina Fancy Feast, Rhodes, NSW, Australia) and empty cardboard egg trays provided harbourage. Water-filled glass vials with cotton wool in the open end provided drinking water. Darkling beetles were purchased from Bugs ‘N’ Things (Oldbury, WA, Australia). They were maintained in a plastic container covered with a cheese cloth lid. Bran and carrots were provided, along with drinking water. Cockroaches and beetles were maintained at a constant temperature of 25 °C ± 1 SE, 12 L:12 D photoperiod, ambient gaseous conditions (21% O₂, 0.03% CO₂) and ambient RH (range 60–80%).