Researching Western Monarch Larvae Development
After 3 months of rearing over 100 monarch larvae on three species of Asclepias L. (milkweed) I am proud to be presenting my preliminary results at the 2016 Summer Undergraduate Research Poster Symposium at the Washington State University, Vancouver. This work was a part of my Research Experience for Undergraduates in the Landscape Ecology and Ecosystem Dynamics in the Columbia River Basin program with my advisor Dr. Cheryl Schultz.
Monarch butterflies, (Danaus plexippus L.) are specialist herbivores of plants in the milkweed family (Asclepiadaceae). In North America, there are two monarch populations which tend to breed on separate sides of the continental divide. The western monarch population overwinters along the California coastal areas before dispersing west to reproduce during the spring and summer. While the eastern North American population has been extensively studied, the western population is less understood and has experienced a steeper decline in the abundance of wintering individuals.
Since the loss of breeding habitat was proposed as a major influence in population declines, the planting of milkweed species in residential gardens and along roadsides has become an increasingly popular conservation practice across North America. However, surprisingly few field or laboratory studies have investigated the survival of western larval monarchs on different native milkweed species. My first research goal was to quantify larvae development on three distinct species of milkweeds: A. fascicularis, A. speciose, and A. syriaca.
Given that many milkweeds grow in close proximity to agricultural fields, there is potential for the plant and thus the monarchs to be exposed to run off insecticides. Neonicotinoid insecticides, the most widely used pesticide class globally, are commonly used as treated seeds for in-plant protection from pests. While these seeds reduce chemical exposure to humans and the environment compared to spraying crops, neonicotinoids have raised concerns for their potential unintended effects on non-target organisms, particularly pollinators. The second goal of this study was to investigate any sublethal effects of neonicotinoids on monarch larval growth and development.
