Ecology of fear: ontogeny‐mediated non‐consumptive effects in a parasite–host system

Non‐consumptive effects (NCEs) arise in the presence of parasites even when infection does not occur and can include changes to host behaviour, physiology or morphology. Using the Drosophila nigrospiracula—Macrocheles subbadius fly‐mite system, we investigated the impact of parasite exposure (sans infection) during the pupal and adult pre‐reproductive stages. First, we exposed fly pupae to mites—either indirectly (caged mites) or directly (free‐roaming mites) to test the effects of parasite exposure on pupation success. Second, we tested how exposing adult female flies to mites prior to reproduction affects fecundity during the post‐exposure reproductive period. We found that direct exposure to mites significantly decreased the rate of successful eclosion (development from pupa to adult) compared with unexposed pupae; however, the duration of pupation was not significantly affected. The indirect exposure did not have a significant effect on either successful eclosion or duration of pupation. We also found that indirectly exposed (caged mites) females had a significant decrease in the number of offspring produced, but only for the first few days post eclosion, suggesting the effect was reversible after mite removal. NCEs arise after mite exposure during the pupal and pre‐reproductive life stage of Drosophila, in the form of decreased eclosion success and fecundity. Investigating the NCEs associated with parasite exposure at various life stages of the host is important in understanding the ecology of fear and its total impact on hosts throughout their entire lifespan, with consequences for host ontogeny and population growth.