Mixed-Species Gardens Increase Monarch Oviposition without Increasing Top-Down Predation
Entomology and Nematology Department, University of Florida, P.O. Box 110620, Gainesville, FL 32611, USA
McGuire Center for Lepidoptera and Biodiversity, Florida Museum of Natural History, 3215 Hull Rd., Gainesville, FL 32611, USA
Author to whom correspondence should be addressed.
Received: 14 August 2020 / Revised: 5 September 2020 / Accepted: 19 September 2020 / Published: 22 September 2020
The North American monarch butterfly is an iconic insect that has recently declined by over 80%, largely due to habitat loss. The primary approach to mitigate population declines is to plant milkweed, the primary host plant that monarch caterpillars feed and develop on. Recently, researchers have focused on optimizing monarch conservation habitats (i.e., milkweed plantings) in urban green spaces by studying habitat design and plant species selection. In many cases, as plant diversity increases, predatory and parasitic insect diversity increases and insect herbivore colonization and establishment decrease. We compared milkweed monocultures to a mixture of milkweed and other wildflower species to see what effects plant diversity have on monarchs and potential predators. We found that monarchs laid 22% more eggs on milkweed planted in mixed-species plots than milkweed in monoculture. We also found more predators in the mixed-species plantings, but this did not affect monarch disappearance rates. These results can be used to create evidence-based guidelines for monarch conservation habitats.