The implications of chemical defence on animal decisions in escape theory
thesisposted on 28.03.2022, 15:53 by Braxton R. Jones
Decisions made by prey during a predator attack have direct impact on fitness. The prey's escape strategy is influenced by a range of factors such as the distance prey are from their refuge, type of anti-predator defence used, location of the predator and speed and directness of predator approach. Although defence type is previously considered, they are primarily limited to either flight decisions or adaptive colouration strategies. In contrast, the implications of possessing chemical defences have been overlooked. In this thesis, I investigate the conditions under which the peppermint stick insect (Megacrania batesii) deploys its chemical defence. Previous lab experiments failed to induce spraying prior to contact which contradicts field observations. This suggested the likelihood of spraying is contextual. Subsequently, I tested the a priori that this stick insect is more likely to use their spray the further they are from their refuge. Results indicate distance to refuge has an influence on the likelihood of spraying. I also describe a novel flight strategy and discuss the implications of these findings relative to escape theory in light of theories on the maintenance of parthenogenesis -- abstract.