RALEIGH – While most people are familiar with Venus flytraps and their snapping jaws, there is still a lot that scientists don’t know about the biology of these carnivorous plants. Researchers have for the first time discovered which insects pollinate the rare plants in their native habitat – and discovered that the flytraps don’t dine on these pollinator species.

Venus flytraps (Dionaea muscipula) are in a genus all their own, and are native to a relatively small area, restricted to within a 100-mile radius of Wilmington.

“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,” said Elsa Youngsteadt, a research associate at North Carolina State University and lead author of a paper on the work. “It also illustrates the fascinating suite of traits that help this plant interact with insects as both pollinators and prey.”

“Everybody’s heard of Venus flytraps, but nobody knew what pollinated them – so we decided to find out,” said Clyde Sorenson, co-author of a paper describing the work and Alumni Distinguished Undergraduate Professor of Entomology at N.C. State.

To that end, researchers captured insects found on Venus flytrap flowers at several sites during the plant’s five-week flowering season. The researchers identified each insect and checked to see if they were carrying Venus flytrap pollen – and, if they were carrying pollen, how much.

Out of about 100 types of insects found on the flowers, only a few were both common and carrying a lot of pollen: a green sweat bee (Augochlorella gratiosa), a checkered beetle (Trichodes apivorus) and the notch-tipped flower longhorn beetle (Typocerus sinuatus).

The researchers also retrieved prey from more than 200 flytraps at the study sites. The three most important pollinator species – despite being found so often on the flowers – were never found in the traps.

“One potential reason for this is the architecture of the plants themselves,” Youngsteadt said. “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.”

But other factors may also come into play.

“We know that the snap traps are different colors than the flowers, and may possibly lure different species,” Sorenson said. “We don’t yet know if they release different scents or other chemical signals that may also differentiate which portions of the plant are attractive to pollinators versus prey. That’s one of the questions we plan to address moving forward.”

Researchers also plan to investigate additional Venus flytrap sites to see if the plant relies on these same core pollinator species in other parts of its native range.

“We also want to learn more about the flytrap’s pollination biology,” said Rebecca Irwin, study co-author and a professor of applied ecology at N.C. 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 said.

The paper, “Venus Flytrap Rarely Traps Its Pollinators,” was published Feb. 5 in the journal American Naturalist. The paper was co-authored by Michael Kunz of the North Carolina Botanical Garden at the University of North Carolina at Chapel Hill; Dale Suiter of the U.S. Fish and Wildlife Service; and Alison Fowler, Sara June Giacomini and Matt Bertone of N.C. State. The work was done with support from N.C. State University.

Front page feature photo: Clyde Sorenson

Reprinted from NC State News

Cold winter weather can play a key role in what you’re allowed to fish for next spring. That point was driven home when low temperatures in early January led North Carolina to temporarily bar fishing for spotted seatrout (Cynoscion nebulosus), one of the most popular targets for recreational anglers.

Stories about isolated fish kills, or “cold stuns,” of spotted sea trout due to cold temperatures date back more than 100 years. But no one knew just how important these cold stuns could be until 2017, when North Carolina State University researchers published new findings on population impacts.

“We had a lot of anecdotes about spotted seatrout, but in order to make good fishery management decisions, you need quantifiable, scientific data,” said Tim Ellis, an ecosystems analyst for the Albemarle-Pamlico National Estuary Partnership, or APNEP, who did research on cold stuns and spotted seatrout while a Ph.D. student at NC State.

Ellis, in collaboration with Joe Hightower and Jeff Buckel of NC State, collected data on the spotted seatrout fisheries in North Carolina and Virginia from 2008 through 2014, work that ultimately led to three publications in 2017 and 2018 that address the impact low temperatures can have on the species. And that impact can be significant.

“The full extent of this month’s cold stun is not yet known, but conditions seemed comparable to what we saw in 2010 – and that year’s cold temperatures led to around 95 percent mortality in spotted seatrout populations in North Carolina and Virginia,” Ellis said.

That’s a big deal, because spotted seatrout are one of the most sought-after species by recreational anglers in North Carolina  – and throughout the southeastern U.S.

“In terms of dollars and cents, the N.C. Division of Marine Fisheries estimates that the recreational fishery for spotted seatrout in North Carolina alone, had a total economic impact of more than $54 million in 2016,” Ellis said.

The importance of this fishery, and the N.C. State findings, are likely why the Division of Marine Fisheries announced Jan. 5 that it was barring commercial and recreational fishing of spotted seatrout in North Carolina waters until June 15, after the species has passed its peak spawning season.

Most spotted seatrout overwinter in shallow, estuarine waters, where water temperatures are strongly affected by the air temperature. That makes the species particularly susceptible to cold snaps like those we saw in the first weeks of 2018.

“In mild winters, spotted seatrout populations can thrive in North Carolina waters,” Ellis said. “But high mortality during cold winters means it could take a while for the fishery to rebound. The fishery is being closed in North Carolina to protect the remaining spawners, in hopes that this will help the species bounce back more quickly.”

“Until Tim decided to take a look, nobody knew how important cold temperatures could be for spotted seatrout at the population level,” Buckel said.

“Ultimately, our research is making a difference,” Ellis said. “We gave fishery managers key information they needed to make informed decisions about how to respond to cold-stun events.”

The three relevant papers are “Relating cold tolerance to winterkill for spotted seatrout at its northern latitudinal limits,” published February 2017 in the Journal of Experimental Marine Biology and Ecology; “Winter severity influences spotted seatrout mortality in a southeast US estuarine system,” published February 2017 in the journal Marine Ecology Progress Series; and “Relative importance of fishing and natural mortality for spotted seatrout (Cynoscion nebulosus) estimated from a tag-return model and corroborated with survey data,” published in January 2018 by the journal Fisheries Research.

The research was done with support from North Carolina Sea Grant (No. 08-FEG-06) and the N.C. Coastal Recreational Fishing License Fund (N.C. Department of Environmental Quality Task Order #2226).

NC State News is published by North Carolina State University and reports breaking news, feature stories and reports from the forefront of education and discovery.

Reprinted from NC State News.

RALEIGH – An economic analysis by North Carolina State University, Oregon State University and RTI International finds that the economic benefits of biodiversity and habitat preservation significantly outweigh the costs of off-road vehicle, or ORV, restrictions at Cape Hatteras National Seashore. The study sheds light on the relative economic value of efforts to balance environmental protection with human access to public lands.

“We found that the upper bound of cost estimates associated with the ORV restrictions was less than even a conservative estimate of benefits,” said Roger von Haefen, an associate professor of agricultural and resource economics at N.C. State and co-author of a paper on the analysis.

At issue are some coastal areas of the Cape Hatteras National Seashore that are nesting sites for endangered sea turtle and bird species. The same areas are also used for recreational purposes and have, historically, been accessed in large part by ORVs. When the National Park Service limited ORV access to these areas in 2012 to protect wildlife habitat, there were concerns that the restrictions would adversely affect recreational fishing, tourism and the regional economy.

To assess the extent of this impact, the researchers collected publicly available data from the National Oceanic and Atmospheric Administration regarding marine recreational fishing. Those data allowed researchers to assess how much recreational fishing took place in the affected areas of Cape Hatteras.

The researchers then used the data to develop an economic model that could predict how recreational fishing behavior may change in response to the ORV restrictions and, ultimately, how much the restrictions may cost recreational anglers.

“There are multiple affected groups here: local businesses and recreational users, including anglers,” von Haefen said. “There are costs to local businesses, but those losses are offset by gains to other businesses in neighboring coastal towns. i.e., if people don’t fish at Hatteras, they likely fish elsewhere in the region. In short, the economic impact to businesses is a wash. The tourism data since the ORV restrictions were put into place bear this out – visitor numbers haven’t dropped.

“That leaves us with addressing costs to the anglers themselves,” von Haefen said. “Specifically, what we’re looking at with our model is the difference between what people are willing to pay for recreational trips to Hatteras – with or without ORV restrictions – and what those people actually pay for those trips – with or without ORV restrictions.”

The researchers found that the cost of the ORV restrictions – the difference between what people are willing to pay and what they actually pay – ranges from $403,000 to $2.07 million per year.

The researchers then added in related costs, such as those associated with administering the ORV restrictions, increased traffic to other coastal areas and impacts on surfers and other recreational beachgoers who aren’t anglers. Altogether, the costs associated with the ORV restrictions came to between $3 million and $12 million per year.

However, peer-reviewed, conservative estimates show that the economic benefits associated with habitat protection measures – what people are willing to pay – range from $13-48 million.

“And that doesn’t include other potential benefits to recreational users, such as beachgoers who prefer to visit areas that don’t allow ORVs,” von Haefen said. “Those benefits also don’t include potential benefits from outside of North Carolina, such as residents from neighboring states who are willing to pay to protect endangered species along the coast.

“This study indicates that the ORV restrictions are actually a net benefit for North Carolina,” von Haefen said. “More generally, our work also offers insights into the value of environmental protection efforts on public lands. That’s particularly relevant given the ongoing national conversation about how to best balance environmental protection efforts and access to public lands.”

The paper, “Recreation Costs of Endangered Species Protection: Evidence from Cape Hatteras National Seashore,” is published in the journal Marine Resource Economics. Lead author of the paper is Steven Dundas, a former graduate student at N.C. State who is now on faculty at Oregon State University. The paper was co-authored by Carol Mansfield of RTI International. The work was supported, in part, by the National Park Service, which has a dual mandate to promote recreational access and environmental preservation on the lands it manages.

Learn More

• ORVs on the Cape Hatteras National Seashore