We tested whether egg-laying female insects could detect differences in predator community composition. Because some predators are more lethal than others, the ability to differentiate predator risk when laying eggs can have large fitness consequences. To test this, we allowed insects to oviposit in tanks that contained a native dragonfly (Ophiogomphus sp.) or a non-native trout brown trout (Salmo trutta). Predators were housed in isolated outdoor tanks either alone (single species) or combined (both species together). Predators were also caged to avoid direct consumption during colonization.
Surprisingly, insect colonization (number of larval insects after 21 days) did not depend on whether predators were present or not, regardless of community composition. However, follow-up consumption trials suggested that laying eggs in predator pools had clear negative consequences for larvae, particularly in trout pools, which reduced larval survival by ~47%. Thus, egg-laying insects either did not (or could not) detect differences in larval habitat quality.