Venus flytraps are surprisingly picky eaters
Poking their snapping jaws up from flowerpots across the globe, the curious nature of Venus flytraps and their carnivorous diets bites at every child's imagination. Although familiar in our own homes, scientists have for the first time discovered which insects pollinate the plants in their native environment, and why they appear to be getting away from being the plant's next meal.
In a genus of their own, Venus flytraps (Dionaea muscipula) are native to subtropical wetlands on the East Coast of the United States, generally within a 100-mile radius of Wilmington, N.C. At several sites during the plant's five-week flowering season, researchers captured and identified insects found on various flowers, checking to see how much pollen they were carrying.
A green sweat bee (Augochlorella gratiosa), a checkered beetle (Trichodes apivorus) and the notch-tipped flower longhorn beetle (Typocerus sinuatus) were found to be the most common and significant pollen-carriers out of approximately 100 types of insects investigated. Interestingly, none of these insects were retrieved as prey from more than 200 flytraps analyzed.
"One potential reason for this is the architecture of the plants themselves," says Elsa Youngsteadt, a research associate at North Carolina State University and lead author of a paper on the work. "Venus flytrap flowers are elevated on stems that stand fairly high above the snap traps of the plant, and we found that 87 percent of the flower-visiting individuals we captured – including all three of the most important species – could fly. But only 20 percent of the prey could fly. The pollinator species may simply be staying above the danger zone as they go from flower to flower, making them less likely to be eaten."
Other possible explanations for these findings include differences in snap trap and flower colorings, which could lure certain species, as well as chemical signals and scents that could potentially discern which sections of the plant are attractive to pollinators versus prey.
"These findings answer basic questions about the ecology of Venus flytraps, which is important for understanding how to preserve a plant that is native to such a small, threatened ecosystem," says Youngsteadt. "It also illustrates the fascinating suite of traits that help this plant interact with insects as both pollinators and prey."
In future studies, researchers plan to expand their site range to investigate whether these same core pollinator species are found in other parts of the plant's native environment.
"We also want to learn more about the flytrap's pollination biology," says Rebecca Irwin, study co-author and a professor of applied ecology at NC State. "How much and what kind of nectar do they produce? How much pollen do they need to reproduce successfully?
"And we know that Venus flytraps need periodic fires in their native habitat in order to thrive, but how do these fire events - and their aftermath - affect the plant's reproductive success? There is still a lot to learn about these plants and their pollinators," Irwin says.
The paper is published in the journal American Naturalist.
Source: North Carolina State University