About 15 years ago, the lab began studying devil’s claw — an introduced plant that is now a host for some species of hornworms. “It’s really surprising that some hornworms use this as a host plant because it’s a completely unrelated plant than their typical hosts, like tobacco,” Kingsolver says. “Initially, we were interested in why this agricultural pest shifted from one plant to another.” Over time, the lab began building upon this relationship layering in other complexities like the role of the parasitoid wasp and climate change.
Parasitoid wasp cocoons are seen on caterpillars raised in the Kingsolver Lab. Most moth and butterfly species have at least one species of parasitoid that can infect them at different stages of life. This particular wasp injects its eggs into the caterpillar. Once hatched, the wasp larvae make their way through the wall of the caterpillar’s body, form cocoons, and develop into adults.
Research technician Tyler Pereira cares for caterpillars and pupae in the lab. Hornworms have long been a model system for researchers. They are easy to care for, grow quickly, and are large — making them ideal for physiological studies. “There’s a lot of things you can do with a hornworm that you can’t do with a fruit fly just because of their size,” Kingsolver says.
When the female parasitoid wasp lays her eggs in a caterpillar, she also injects a virus that suppresses the caterpillar’s immune system and protects those eggs. At varying degrees, the wasp, her eggs, and larvae are more sensitive to increasing temperatures than the caterpillar. Increased heat can also suppress the virus. Malinski wants to better understand why this breakdown occurs.
Katherine Malinski, a PhD student, checks a light trap at the North Carolina Department of Agriculture and Consumer Services’ Central Crops Research Station. Malinski uses two species of hornworm as study systems: Manduca sexta and Manduca quinquemaculata, called quinqs. While the former are easy to care for in the lab, quinqs are more finicky. Malinksi hopes capturing female moths to lay eggs in the lab will prove more successful than collecting wild quinq caterpillars.
In a pilot study, Malinksi found that about 50 percent of parasitized quinqs that were heat shocked lived and completed development. In comparison, only about 5 to 10 percent of parasitized, heat shocked Manduca sexta survived. She is continuing that work to better understand why the outcome differs between species and what role the parasitoid wasp plays in that scenario.
Anna Parker, a PhD student, and Pereira repot plants in the UNC Biology Greenhouse. Parker’s research is focused on the role devil’s claw and tobacco play in the relationship between the hornworms, parasitoid wasp, and climate change.
Pereira repots a devil’s claw plant in the greenhouse. As a host plant, devil’s claw is inferior to tobacco plants — the caterpillars have higher mortality, reduced immune function, and slower growth. But caterpillars are far less likely to be parasitized on devil’s claw. “There’s this tradeoff for an adult female moth laying her eggs,” Parker says. “Does she lay them on tobacco which is a better plant but they have a good chance of getting parasitized and die? Or does she lay them on devil’s claw, where they might die since it’s not a great host but they won’t get parasitized?”
This summer, Parker’s field work involves putting parasitized hornworms on devil’s claw and tobacco plants in an experimental garden at Mason Farm Biological Reserve and observing how they affect the plants’ lifecycles. In high heat, the parasitoid wasp larvae are killed, but the virus persists. The result is called a WOWE (With Out Wasp Emergence) — a caterpillar that will continue to grow and eat, but will never molt and turn into a pupa. A healthy caterpillar is about 12 to 15 grams. A WOWE can be double that size. Parker is specifically using WOWEs in her experiment, seeing how they affect the development and reproductive success of the plants.
Former PhD student Elizabeth Moore catches a butterfly at Mason Farm Biological Reserve. In 2016, Moore and other graduate and undergraduate students created the Mason Farm Butterfly Project, a collaboration with the North Carolina Botanical Garden using citizen science to track butterfly sightings. This year, the lab will begin to pore over the data, searching for trends in butterfly abundance and flight times. The Kingsolver Lab puts special emphasis on community outreach, hosting hands-on activities for young students, producing podcasts and education software, and giving public presentations on butterfly evolution and climate change.
Moore holds an Appalachian brown butterfly, one of about 175 species of butterfly found in North Carolina and 75 found at Mason Farm. Butterflies and moths are indicator species — animals whose abundance and health provides information on the overall condition of their ecosystem. “Because they’re so tightly tied to their host plants and only occur in certain habitats, they’re wonderful canaries in the coal mine,” Kingsolver says. “They’re really useful study systems because we can detect ecological changes with butterflies and moths often before we can detect them through other beings.”
After six years in the Kingsolver Lab, Moore has received a postdoctoral fellowship at NC State University. While Moore’s place of work has changed, her infatuation with insects remains. “I just think they’re so fascinating,” she says. “They’re vital to basically every single ecosystem on the planet. So understanding how these ecological interactions will be affected by humans is important to be able to preserve and enrich our ecosystems.”