|Fly with pollen visiting a parsnip umbel|
When plants colonize new places they usually arrive without any of their natural enemies and pollinators. The wild parsnip is native to Europe, as is its principal herbivore, the parsnip webworm, a flower- feeding caterpillar. Both species have been accidentally introduced into North America and New Zealand. In North America, wild parsnips first appeared in the 17th century and parsnip webworms were accidentally introduced approximately 250 years later. In contrast, wild parsnips arrived in New Zealand in the mid-19th century and parsnip webworm arrived very recently, in 2004. Pollinator attraction and herbivore defence are both mediated by floral chemistry. Prior to the arrival of its major herbivore, wild parsnips in New Zealand produced lower levels of chemical defences (volatiles). The goal of our study was to determine whether, in the absence of their primary enemy, wild parsnips in New Zealand are more attractive to pollinators.