Nurseries and commercial plant producers are crucial to providing milkweed and nectar sources required for monarchs to rebound. However, limited communication between conservationists and commercial nurseries represents a major obstacle to harnessing consumer power in providing monarch habitat. Many nurseries in the southern U.S. either do not provide milkweeds or offer only a single exotic species (tropical milkweed, Asclepias curassavica), despite the diversity of milkweeds that are native to North America. However, even nurseries selling native milkweeds often provide plants that have been treated with systemic insecticides, which persist for months and are expressed in all parts of the plant including the leaves and nectar. A 2014 report by Friends of the Earth found that ~50% of nursery plants contained residues of neonicotinoid insecticides, although milkweed plants were not tested. Recent research found that milkweed treated with the neonicotinoid imidacloprid, at a level commonly applied to ornamental plants, reduced monarch caterpillar survival (Krischik et al. 2015). Gardeners frequently report pesticide-induced deaths of monarch larvae after purchasing milkweed. In addition, native flowering plants that serve as preferred nectar sources for monarchs (e.g., frostweed, false foxglove) can be challenging for consumers to find and are also treated with systemic insecticides.Motivating and equipping nurseries with information to meet consumer demand for native, insecticide-free milkweed and nectar sources could increase monarch production in garden habitats of North America.
The primary aim of this 2016-17 project is to enhance native milkweed and nectar plant availability by communicating with and providing information to nurseries. Involved MJV partners will visit or call local nurseries in Georgia and Texas to establish relationships in which we can share information about monarch habitat, monarch declines, and consumer demand for pollinator-friendly plants. Based on these discussions, a survey will be developed and distributed to a broader group of plant suppliers across the southern U.S. to understand the current knowledge, interests, and challenges that limit or support the capacity for nurseries and growers to offer pesticide-free, native plants for monarch habitat. Upon completion of the study, findings will be made available on the MJV website.
Friends of the Earth 2014 Gardeners beware: Bee-toxic pesticides found in ‘bee-friendly’ plants sold at garden centers across the U.S. and Canada.
Krischik, V., Rogers, M., Gupta, G. & Varshney, A. 2015 Soil-Applied Imidacloprid Translocates to Ornamental Flowers and Reduces Survival of Adult Coleomegilla maculata, Harmonia axyridis, and Hippodamia convergens Lady Beetles, and Larval Danaus plexippus and Vanessa cardui Butterflies. PLoS ONE 10, e0119133. (doi:10.1371/journal.pone.0119133)