“…The response of a natural enemy to increasing host density (functional response) is important for the outcome of parasitoidbased biocontrol programs (Berryman, 2004) and together with the numerical response an indispensable element in their biological characterization (Cedola et al, 2001, Gilioli et al, 2005 and an important determinant of their effectiveness as biological control agents (Houck & Strauss, 1985;Jost & Ellner, 2000). Different factors may influence their functional responses, including host plant surface traits (Coll & Ridgway, 1995;Messina & Hanks, 1998;Madadi et al, 2007), host species (Mansfield & Mills, 2004), natural enemy life stages (Seko & Miura, 2008), host age (King, 1994;Ode & Strand, 1995) and spatial complexity (Madadi et al, 2011).…”