A research team has just discovered that an ornamental plant called the parachute plant captures prey through mimicry. The plant releases chemicals that replicate the scent of bees under attack, attracting carnivorous flies. The findings are in a paper that was just released in the journal Current Biology.
The parachute plant (Ceropegia sandersonii) is a flowering ornamental plant popular with indoor gardeners. Parachute plants are succulents that are native to Africa, with cultivated varieties often kept as houseplants. C. sandersonii attracts Desmometopa flies, which become trapped in the corolla tube. They’re released later, covered in pollen. This pollination strategy is well-known but scientists were unsure how C. sandersonii were luring the flies.
Desmometopa flies are kleptoparasites, a type of parasite that steals food from other animals. Desmometopa species specifically feed on honeybees that have been captured by spiders. Researchers from the University of Bayreuth speculated that parachute plants were somehow taking advantage of the flies’ feeding strategy.
The team found that C. sandersonii plants were releasing compounds that mimicked the same chemicals released by trapped honeybees. When honeybees are attacked, they release drops of venom that contain alarm pheromones. These chemicals are a cry for help and alert the other bees in the colony to the danger. Carnivorous Desmometopa flies take advantage of these signals and use them to find bees to prey on. C. sandersonii plants release similar compounds, including the chemicals geraniol, 2-heptanone, 2-nonanol, and (E)-2-octen-1-yl acetate. This attracts the flies, allowing C. sandersonii to trap them and achieve pollination. This represents an odd example of a plant utilizing the scent of a carnivorous animal’s prey in order to lure pollinators.
The research team is now studying the reproduction of other fly-pollinated plants in the Ceropegia genus. The team speculates that other plant species use similar deceptive strategies to lure kleptoparasitic flies.
Heiduk et al. Ceropegia sandersonii Mimics Attacked Honeybees to Attract Kleptoparasitic Flies for Pollination. Current Biology (2016).