Edge effects on the prevalence and mortality factors of Phytomyza ilicis (Diptera, Agromyzidae) in a suburban woodland


Melodie A. McGeoch mamcgeoch@zoology.up.ac.za


Although the effects of edges on the biotas of habitat patches have been widely discussed, there have been few empirical studies of the mechanistic basis of population and community differences between patch edges and interiors. This is particularly true of differential effects of edges on species’ mortalities, and on interactions in insect populations and communities. Here we examine edge-associated differences in the prevalence and mortality factors of the holly leaf-miner Phytomyza ilicis, in a suburban woodland in Sheffield, U.K. Leaf miner prevalence was higher and survivorship to adulthood lower at the woodland edge. Natural enemies and other mortality factors contributed differently to total mortality at the edge and interior. Mechanisms underlying edge effects on P. ilicis arose from the interaction between microclimate, adult movement and host-plant quality. The differential induction of species mortality found, confirms the complexity of species’ responses to habitat edges and the importance of understanding the effects of edges on species interactions.