Pre-dispersal seed predation obscures the detrimental effect of dust on wildflower reproduction - fruit data

Premise of the Research. Seed production by flowering plants depends on abiotic and biotic factors whose interacting effects may be hidden. We previously reported that exposure to dust from unpaved roads reduced the average amount of pollen on flowers of Ipomopsis aggregata, but did not consistently reduce mean seed set per fruit. Here we explore one possible explanation—that the expected detrimental effect of lower pollen loads on seed production was obscured because dust reduces not only pollination success but also attack by a pre-dispersal seed predator. Methodology. Over three consecutive summers we scored the fates of over 4,000 flowers, comparing those on hand-dusted I. aggregata plants to those on clean control plants in the same natural populations. We censused plants throughout each flowering season, marking phenological cohorts of flowers and examining them for eggs of the Anthomyiid fly Hylemya sp. We subsequently scored expanded fruits for seed loss to Hylemya larvae. Pivot...