What’s an aphid to a monarch? Effects of oleander aphid on monarch conservation efforts

Widespread declines in pollinator populations have spurred the need for new and data-based conservation efforts. Monarch butterflies (Danaus plexippus, L.) are an important and highly charismatic group of pollinators. Despite their popularity, monarchs are a species of conservational concern due to declining populations. One obstacle to monarch conservation efforts is competition with other insects that feed on the monarch’s sole larval host, milkweed. The oleander aphid (Aphis nerii, Boyer de Fonscolombe) is a common pest of milkweed that can reduce the fitness of milkweed plants via sap-feeding as well as promoting sooty mold growth. We hypothesize that increased aphid density will reduce monarch fitness by reducing oviposition site availability and quality of consumable plant tissue. This research examines how the presence of oleander aphids on milkweed affects the behavior and fitness of both adult and larval monarchs. We compare monarch oviposition patterns and larval development and survivorship on aphid infested and aphid-free milkweed plants. Results from this research will help inform future conservation efforts and pest management strategies.