Parasitoid communities of remnant and constructed prairie fragments in western Ohio

Background/Question/Methods

The ability of organisms to disperse to, utilize, and persist in novel habitats in a patchy landscape is vital to the success of habitat construction and restoration efforts in which the translocation or introduction of organisms is not practical (i.e. invertebrate communities). With less than four percent of original tallgrass prairie remaining in North America, conservationists have made efforts to both preserve remaining prairies and to construct new prairie habitats, often in novel and isolated locations. Here, we aim to assess the ecological functionality and similarity of remnant and constructed prairie fragments in western Ohio by examining the abundance, diversity, and composition of insect parasitoid communities in these ecosystems.

Pan-trapping was conducted on eight occasions in fifteen field sites (five remnant prairies, five constructed prairies, and five old-fields) from May to September 2014. All parasitoids were identified to family, with special emphasis placed on members of the family Tachinidae (Diptera), which were identified to species-level. We tested for effects of habitat type (remnant prairie, constructed prairie, or old-field), patch size, and plant community diversity on parasitoid/tachinid abundance and richness. We conducted an ordination analysis to compare tachinid community composition similarity within each site type.

Results/Conclusions

Preliminary ANCOVAs showed no effect of site type, patch size, or plant community diversity (both richness and effective number of species) on parasitoid/tachinid abundance and richness. Non-metric multidimensional scaling found similarly high levels of ecological distance in the tachinid communities of remnant and constructed prairies, while the mean ecological distance between old-field sites was significantly smaller (p = 0.0273).

Our data suggest that remnant and constructed prairies may be functionally similar in their ability to provide habitat for highly variable tachinid communities. Although old-field sites did not differ from the two types of prairie in their mean parasitoid abundance and richness, the smaller ecological distance between sites indicates that old-fields may support a more homogeneous parasitoid community. The planting of new prairies may thus be an effective means of maintaing biodiversity at the landscape-level, if not at the site-level.