Anoxia tolerance of the adult Australian Plague Locust (Chortoicetes terminifera)

Optimal breeding conditions for locust swarms often include heavy rainfall and flooding, exposing individuals to the risk of immersion and anoxia. We investigated anoxia tolerance in solitarious and gregarious adults of the Australian Plague Locust, Chortoicetes terminifera, by measuring the time to enter an anoxic coma after submersion in water, the time for recovery of ventilation and the ability to stand on return to air. We found a longer time to succumb in immature adults that we attribute to a larger tracheal volume. Time to succumb was also longer after autotomizing the hindlegs to reduce the energetic cost of muscular activity. Time to recover was longer in gregarious males and this developed during maturation, suggesting an increase in the cost of neural processing associated with social interactions under crowded conditions. Short-term changes in rearing conditions had effects that we interpret as stress responses, potentially mediated by octopamine.