Beyond the ecology of fear: non-lethal effects of predators are strong whereas those of parasites are diverse

Individuals can alter their behaviour and other traits to reduce threats from predatorsand parasites. However, predatorsand parasiteslikely elicit different responses, which subsequently lead to different non-lethal effects. We created a sequentially structured framework to examine trait responsesto distinct predatory and parasiticconsumers. We predicted that parasiteswith strong negative effects on host fitness should act like predatorsand elicit strong responsesbefore attack. We also predicted that less damaging parasitesand micropredators should elicit diverse responsesacross multiple interaction stages, because their hosts and prey remain alive while being eaten. A meta-analysis indicated that predatorsdo tend to elicit stronger responsesthan parasitesbefore attack, whereas parasitesgenerally elicit responsesafter attack, albeit weaker than pre-attack responsesto predators. Organisms exposed simultaneously to predatorand parasitecues responded similarly when exposed to predatorcues alone, suggesting that individuals prioritize anti- predator responsesover responsesto less harmful parasites. Extending these findings requires addressing knowledge gaps concerning responsesto different consumer types, costs of immune responses, and cumulative effects of repeated responses. Expanding research beyond the predatorvs. parasitedichotomy toward a broader consumer-resource perspective will facilitate understanding of non-lethal effects in complex, multi-trophic food webs.