*Focal observations might reveal some NCEs related to expression of anti-predator behaviors, although would be unlikely to quantify the costs of such behaviors.
†This method could capture the costs of some NCEs if those costs were expressed through a reduction in developmental survival rates.
‡ Purely correlative studies examining associations between densities of predators and prey or hosts and parasitoids are also sometimes reported. But, without additional evidence of a causal link (and support for the direction of causality) such studies are often open to multiple interpretations. Thus, we omit them from the current discussion.
Fig. 1: Demonstration of a particular enemy-risk effect fitting in to the broader framework we describe in Box 2. An enemy-risk effect is described by both the stage, beginning with individual response and ending with community effects, as well as by the effects on the abundance, distribution, and characteristics of a pest population.