none It has been suggested that the effects of the spatial configuration of host plant on populations of herbivorous insects and their natural enemies may be different. This paper assesses the effect of patch shape and surrounding non-host vegetation on Plutella xylostella and on its parasitism. There were two patch shapes with opposite perimeter/area relationship and two surrounding non-host vegetation, Allium porrum and Medicago sativa. Plutella xylostella was not affected by patch shape but was significantly affected by both the surrounding vegetation and the interaction surrounding vegetation-patch shape. The effect of these variables was indirect, through the effect on the plant biomass. The parasitism rate was high and similar in all patches, suggesting that guild of parasites was density-independent of the host abundance. Nutrition; Diet; Parasites diseases and disorders; Parasites; Insect parasites; Hosts; Insect hosts; Land zones; Neotropical region; South America Plutella xylostella (Plutellidae); Food plants; Brassica oleracea (broccoli); Patch size & surrounding vegetation effect on hymenopteran parasite guild; Hymenopteran parasites; Apanteles; Diadegma & Tetrastichus; Chile; Santiago; Centro Regional de Investigaciones La Platina; Hymenopteran parasite guild prevalence, food plant patch & surrounding vegetation relationship Apanteles piceotrichosus (Braconidae ); Diadegma leontinae (Ichneumonidae ); Tetrastichus sokilowoskii (Eulophidae ); Lepidopteran hosts; Plutella xylostella; Guild prevalence; Chile; Santiago; Centro Regional de Investigaciones La Platina; Lepidopteran host prevalence, host food plant patch & surrounding vegetation relationship