Effect of Simulated Herbivory on Narrow-leaved Milkweed (Asclepias fascicularis)

Abstract

The Narrow-leaved Milkweed is a native species that serves as an important host plant for
Monarch butterflies in California. Monarch caterpillars and other herbivores (e.g., aphids)
tolerate the chemical defenses produced by the plant, causing some damage to it while feeding. Research on other milkweed species has shown that herbivory can affect the plant’s allocation of resources (e.g., slower growth in plants attacked by herbivores), but the impact of leaf damage on Narrow-leaved Milkweed remains unclear. In this project, we conducted a field experiment to test if Narrow-leaved Milkweed plants are affected by leaf damage similar to that caused by herbivores. The experiment involved a simulated herbivory treatment (leaf damage), which consisted of clipping 50% of the leaves of seedlings (<6 months old; up to 10 leaves clipped) and older plants (>2 years old; up to 30 leaves clipped). No leaf clipping was applied to a control group, and an equal number of plants were assigned to the leaf damage treatment and control group (no damage). After eight weeks, we measured plant growth and aphid abundance to assess any differences between the experimental groups. Our study provides insight into the variation in plant growth and aphid abundance observed in response to simulated herbivory. Additionally, we discuss different strategies (tolerance vs. resistance) that milkweed plants may use to cope with herbivore attacks.

Details

Session 2

1:30pm – 2:45pm

Del Norte Hall

Room D: 1530

HSI-SMART