Refuge for native lady beetles (Coccinellidae) in perennial grassland habitats
- The proportion of native individuals in North American lady beetle communities has declined precipitously over the past 30 years, particularly in annual cropping systems. At the same time, the number and abundance of exotic coccinellid species have been on the rise as beetles are introduced both inadvertently and intentionally for the purposes of biological control.
- Perennial grasslands have been proposed as refuge habitats that promote native lady beetles, either by resisting the invasion of exotics or by providing a consistent source of shelter and resources.
- Our objective is to compare the conservation value for native lady beetles of different perennial grassland habitats that vary in their degree of habitat modification and disturbance.
- The abundance, species richness, and species composition of native and exotic lady beetles were compared across remnant native tallgrass prairies, native tallgrass prairies actively restored from cultivation and exotic tall fescue grasslands grown as forage crops.
- Native species dominated the lady beetle community in all perennial grassland habitats, with more than 95% of captured individuals being native in origin. Exotic lady beetle species were equally rare across all habitat types.
- The grassland habitat considered the most disturbed, agriculturally grown exotic tall fescue, had the highest abundance and species richness of native lady beetles and a unique composition of species as compared to prairie habitats. Lady beetle communities in remnant and restored tallgrass prairies were indistinguishable, indicating that prairie restoration successfully re-established coccinellid communities.
- Promoting perennial grasslands, both natural and agricultural, within disturbed landscapes has the potential to enhance native lady beetle populations.