Habitat complexity mediates spatiotemporal niche partitioning among native and invasive seed predators

Flower diversity on organic farms increases invasive ants rather than non‐invasive natural enemies

“…Predator evenness 36 0.14 Solenopsis invicta abundance 37 0.24 diversity and pest suppression (Blubaugh, Asplund, Judson, & Snyder, 2021;Blubaugh, Asplund, Smith, & Snyder, 2021;Feit et al, 2019), yet it is still unclear why plant communities most effectively promote predator evenness (Snyder, 2019). Previously, we found that weedy plant cover was a source of evenness among natural enemies in the Northwestern USA (Blubaugh, Asplund, Judson, & Snyder, 2021;Blubaugh, Asplund, Smith, & Snyder, 2021) Evidence is mounting that dominant invasive predators, like fire ants, might interfere with the relationships between biodiversity and biocontrol (Blubaugh et al, 2022;Blubaugh, Asplund, Judson, & Snyder, 2021;Snyder et al, 2004). Invasive arthropod predators tend to share characteristics that enable their domination of insect communities, such as disturbance tolerance, competitiveness and frequent intraguild predation Snyder & Evans, 2006).…”

“…In agroecosystems in the Pacific Northwestern United States, another dominant invasive predator, the ground beetle Pterostichus melanarius Illiger, benefits from non-crop diversity, disrupting links between non-crop plants and evenness among native natural enemies (Blubaugh, Asplund, Judson, & Snyder, 2021). In the Southeastern USA, vegetative cover attracts red imported fire ants during the heat of the summer and displaces native weed seed predators to sub-optimal microclimates (Blubaugh et al, 2022). Together, our results and previous observational studies suggest that non-crop plantings intended to strengthen insect predator diversity have the potential to backfire when dominant and invasive predators are added to the mix.…”

“…Evidence is mounting that dominant invasive predators, like fire ants, might interfere with the relationships between biodiversity and biocontrol (Blubaugh et al, 2022; Blubaugh, Asplund, Judson, & Snyder, 2021; Li, Li, et al, 2021; Snyder et al, 2004). Invasive arthropod predators tend to share characteristics that enable their domination of insect communities, such as disturbance tolerance, competitiveness and frequent intraguild predation (Crowder & Snyder, 2010; Snyder & Evans, 2006).…”

“…These ants are well adapted to early successional habitat (Tschinkel & King, 2013) and, thus, often thrive under conditions of high ecological disturbance (King & Tschinkel, 2008). Red imported fire ants also benefit from plant cover (Blubaugh et al, 2022; Harvey & Eubanks, 2004; Lewis et al, 2020; Tschinkel & King, 2013), but it is less understood how they respond to floral resources. Thus, it is important to consider how different sources of plant diversity and dominant invaders each shape the community structure of resident insect predator communities.…”

“…We predicted that evenness among non‐invasive predators would decrease with the abundance of an invasive predator, the red imported fire ant, Solenopsis invicta Buren (Blubaugh, Asplund, Judson, & Snyder, 2021; Chan & Guénard, 2020). It is currently unclear how fire ants might complicate links between non‐crop plants and insect predators due to evidence of fire ants both thriving under high disturbance (King & Tschinkel, 2008) and in response to vegetation (Blubaugh et al, 2022; Harvey & Eubanks, 2004; Lewis et al, 2020; Tschinkel & King, 2013). Finally, we expected that by increasing niche saturation and reducing antagonistic interactions (Snyder, 2019), evenness among natural enemies would predict strong increases in the abundance of natural enemies (Blubaugh, Asplund, Judson, & Snyder, 2021; Blubaugh, Asplund, Smith, & Snyder, 2021; Crowder et al, 2010).…”