A larva of the mosquito Aedes notoscriptus

 

Predation is a highly selective force that drives the evolution of defences in prey that increase their chances of escape and survival. Predation can vary spatially and temporally, so for some prey it’s better to induce defences only when predators are present. One of the requirements for the evolutionary maintenance of inducible defences is a functional trade-off between the induced and non-induced phenotype. That is, the induced phenotype must have a selective advantage in the presence of predators but must be costly in their absence. Without a cost to inducible defences, we would expect the defences to be a fixed phenotype. The adaptive benefits of induced defences are well established across many predator-prey systems. However, the theoretical costs of inducible defences are poorly supported by empirical data.

  

  

A model predator, the Firetail Gudgeon Hypseleotris gallii

 

Mosquito larvae are one such animal that displays inducible defences in the presence of predators. In response to chemical predator cues many mosquito larvae will reduce activity to make themselves less conspicuous and more likely to escape predation. However, reducing activity must constrain total foraging time and therefore, the amount of energy they can acquire during their larval period. We intend to examine the costs of the behavioural response to predators to larval growth, development and longevity as adults. If the costs are substantial, synthetic chemical cues may provide a novel control method for mosquitoes that are major vectors for human pathogens.