Carbon dioxide versus cold exposure for immobilising live redback spiders Latrodectus hasseltii Thorell, 1870 (Araneae: Theridiidae)

Studying live spiders often involves non-lethally immobilising them. The use of CO2 and refrigeration were investigated, both alone and combined, as methods for immobilising redback spiders (Latrodectus hasseltii). Specimens of L. hasseltii were exposed separately to CO2 and cold temperatures (4.2°C) for time intervals ranging from 5 to 12 s and 4 to 45 min, respectively. Subsequent behaviour exhibited by the spiders was described as either positive or negative: if handling and removal from the container were possible without risking escape or injury this was described as a positive reaction. Conversely, if the spider was too active to be handled the reaction was counted as negative. Two minute CO2 exposure had a significant positive effect on spider response; refrigeration and combining the two treatments did not produce significant effects. Carbon dioxide was the most successful method of immobilising spiders; however, we caution using it for endangered species until further research has been conducted into long-term effects.