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

Although the effects of edges on the biotas of habitat patches have been wi dely discussed, there have been few empirical studies of the mechanistic ba sis of population and community differences between patch edges and interio rs. This is particularly true of differential effects of edges on species' mortalities, and on interactions in insect populations and communities. Her e we examine edge-associated differences in the prevalence and mortality fa ctors of the holly leaf-miner Phytomyza ilicis, in a suburban woodland in S heffield, U.K. Leaf miner prevalence was higher and survivorship to adultho od lower at the woodland edge. Natural enemies and other mortality factors contributed differently to total mortality at the edge and interior. Mechan isms underlying edge effects on P. ilicis arose from the interaction betwee n microclimate, adult movement and host-plant quality. The differential ind uction of species mortality found, confirms the complexity of species' resp onses to habitat edges and the importance of understanding the effects of e dges on species interactions.