Pollinators and natural enemies show different preferences for native plant species

Wild pollinators and natural enemies provide important ecosystem services to agriculture. Yet these insects, mainly bees and predatory or parasitoid wasps and flies, may be negatively affected by agricultural land use. Habitat restorations are used to restore these insects on agricultural lands, but few studies exist to guide these efforts. In particular a science-based understanding of which native plants attract both pollinators and natural enemies is lacking. We experimentally tested twenty native, perennial plant species for their attractiveness to pollinators and natural enemies using a randomized array of 120 single-species plots in Cape May, New Jersey. Each functional group showed strong preferences for particular plants. For both natural enemies and pollinators, 80% of visits were to only four plant species (for natural enemies, chi-squared=94.47; P<0.001; for pollinators, chi-squared=74.58; P<0.001). Floral density was not a strong predictor of insect visitation, indicating that plant species identity may be more important than floral abundance in attracting these ecosystem service-providing insects. The identity of the plants preferred by pollinators and those preferred by natural enemies were not strongly correlated (Spearman’s r=0.39; P<0.001), with only one plant species preferred by both groups. These results suggest that out of the twenty plant species tested, a minimum of seven would be needed to encompass the preferences of both insect groups within restoration plantings. Thus, it is possible to create targeted restorations that are streamlined and beneficial for multiple functional groups.