Effects of urbanisation on the parasitoid community of a leafminer

FENOGLIO, M. S.; SALVO, A.; ESTALLO, E. L.

ACTA OECOLOGICA-INTERNATIONAL JOURNAL OF ECOLOGY

GAUTHIER-VILLARS/EDITIONS ELSEVIER

Año: 2009 vol. 35 p. 318 - 326

1146-609X

Urbanisation may have detrimental effects on communities of parasitoids, affecting theirspecies richness, abundance, and species dominance. Here we investigated the influence ofthe  degree  of  urbanisation  on  parasitoid  communities  of  Liriomyza  commelinae  (Frost)(Diptera: Agromyzidae), a leafminer of Commelina erecta L. (Commelinaceae), in the city ofCo´ rdoba,  Argentina.  To  study  changes  in  species  richness,  the  specific  composition  ofparasitic complexes and their degree of impact on the leafminer, 18 sampling sites fromthe centre to the outskirts of the city were selected and different variables indicative ofurbanisation were quantified in each site. During January and February of 2005 and 2006, allmined leaves found in each plant patch were collected and the following variables wereestimated:  proportion  of  mined  patches,  abundance  of  the  leafminer,  total  parasitoidspecies richness, total parasitism rates and parasitism due to the most abundant parasitoidspecies.  The  percentage  of  mined  patches  and  leafminer  abundance  increased  withurbanisation  degree.  Estimates  of  parasitoid  species  richness  were  not  influenced  byurbanisation degree but increased with species richness of mined plants. Changes in thespecific composition of species along the urbanisation gradient were observed. Althoughparasitism by one of the species studied was higher in more urbanised sites of the city, thetotal parasitism  rate of  L. commelinae  was  not  affected  by  urbanisation  degree,  speciesrichness of mined plants or leafminer abundance. It appears that urbanisation benefits theherbivore species here studied but not through altering parasitoid activity. Changes inparasitoid community composition reflex dissimilar tolerance to environmental conditionsdisplayed by different parasitoid species.