A Wolf in Ladybug's Clothing
[-Back to Villains in Vacationland-]

Photo by Jeff Garnas

Lady beetles, commonly referred to as ladybugs, and their grub-like larvae are one of the primary predators of aphids, gorging themselves on the largely immobile herbivores and thereby helping to control aphid populations. Imported fire ants interrupt this natural balance by attacking any lady beetle that might threaten their aphid flock.

By setting up artificial aphid "farms," University of Maine Ph.D. student Christie Finlayson has discovered a way to compare the defensive behaviors of native lady beetle species with their non-native counterparts.

"My research shows that non-native species of lady beetles have become dominant over native lady beetle species in almost all habitats in Maine," says Finlayson, who specializes in the ecological role of non-native species in the environment. "I wanted to see how different species of lady beetles react in the presence of predators like fire ants."

Finlayson set up trials where native and non-native beetles visited ant-protected aphid colonies, developing a specialized rating system to chart both the ants' levels of aggression and the beetles' reactions. While the data from dozens of trials is still being analyzed, Finlayson suspects that the project may reveal that some non-native lady beetles are better equipped to handle predation, giving them a competitive advantage over their native counterparts.