Submitted to: Journal of Entomological Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/30/2017
Publication Date: 10/1/2017
Citation: Greenstone, M.H., Cornelius, M.L., Olsen, R.T., Payton, M.E. 2017. Test of a natural enemy hypothesis on plant provenance: Spider abundance in native and exotic ornamental landscapes. Journal of Entomological Science. 52(4):340-351. Interpretive Summary: Urban residents and builders face many choices regarding native or exotic (non-native) woody plants when landscaping their properties. There is little information about how these plantings will affect ecosystem services such as biological control of insect pests. We reason that biological control will be more effective in landscapes composed of native plants because native natural enemies of pests have evolved for millions of years with native plants, and are therefore better able to use the resources provided to them by native plants than those provided by exotic plants, with which they have no recent evolutionary history. To test this hypothesis we performed an experiment in which simulated backyards were created by planting either native or very closely related exotic woody plants. We placed egg masses of the brown marmorated stink bug on plants known to be attacked by this pest, and observed the egg masses to see what kinds of insect natural enemies visited them. Members of one important class of natural enemies, spiders, were significantly more abundant near egg masses in the native than in the exotic plots, a finding that supports the hypothesis. These results will be of interest to scientists, pest management specialists, homeowners, builders, and urban planners.
Technical Abstract: There is heightened interest in effects that the provenance of plants in the landscape has on animals inhabiting them. There is an increasing body of research on insect herbivores, but less attention has been paid to arthropod natural enemies. This question is of great interest for designers of urban ornamental landscapes, which tend to be mosaics of native and exotic plants. Many commonly grown exotic woody plants were missing from eastern North America for millions of years prior to the arrival of Europeans. We present the hypothesis that due to the lack of a recent co-evolutionary history with these plants, native natural enemies will be less well able to utilize the resources – architectural features and nutritional supplements – provided by exotic plants than they will those of native plants, and hence will be less numerous and diverse in landscapes dominated by exotic plants. To test the hypothesis, we designed a replicated experiment comprising 0.08 Ha plots planted to congeners of 16 genera of woody plants from either Eurasia or North America. Spiders attending egg masses of the brown marmorated stink bug, Halyomorpha halys, emplaced on leaves of a subset of plant species known to be attacked by this pest, were statistically less abundant in the exotic plots, supporting the hypothesis.