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Separate Studies Inventory Bees of the Black Hills and South Dakota Badlands

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Every five meters as the crow flies, up and down mountain meadows, he places another trap — a blue, yellow, or white plastic dish of soapy water, intended to lure bees. The soap breaks the surface tension of the water so that the bees, checking out what looks like a flower, slip in and drown. After leaving a line of 30 traps in place for 12 hours, Drons will gather up the day’s haul and place the insects in bags, to be identified through painstaking hours in the laboratory later this year.

A graduate student of South Dakota State University professor Paul Johnson in SDSU’s Department of Plant Science, Drons is carrying out the fieldwork for the first major inventory of the native bees in the Black Hills. Johnson, an entomologist, said biologists know that at least 100 species of bees are found in the region. But there’s a possibility that perhaps 80 or more additional species could be found there.

By coincidence, scientists Diane Larson and Sam Droege of the U.S. Geological Survey are running a parallel project in nearby Badlands National Park. They are doing a two-year inventory of the bees found on native mid-grass prairies of the park. Larson, of the USGS Northern Prairie Wildlife Research Center in St. Paul, said the work focuses in part on the interaction webs that link rare and invasive plants with pollinators and with each other.

“Badlands National Park is home to nine plant species considered rare in South Dakota, as well as several invasive exotic plants, many of which vie for pollinator services with the rare species,” Larson said. “A key question is, if bee species necessary for pollination of rare plants have come to depend on invasive flowers, what must we do to ensure the bees' survival as we control the invasives?”

The Badlands study is also helping to establish baseline data about the pollinator species found in the park. Initial specimens collected this spring have already generated more than 10 new state records for South Dakota, said Droege, of the USGS’s Patuxent Wildlife Research Center in Maryland. Many of those specimens represent the northernmost and easternmost extensions of a species' range from the west.

“The Dakota prairies have perhaps the least known bee fauna in the United States,” Droege said. “We expect to detect at least a handful of undescribed species in this project due to the remoteness and understudied nature of the region. It is extremely fortuitous that both Paul and David's survey of the Black Hills is occurring at the same time using similar methods as it will be very interesting to contrast the vegetatively highly diverse Black Hills region with the more uniform grasslands of Badlands National Park.”

Like the Badlands study, the Black Hills Bee Project will develop basic biological knowledge on what species of bee are found in the region, their distribution, the habitats they prefer, their host plants, geospatial data and other ecological attributes of the native pollinators. With the rest of summer 2010 and summer of 2011 still scheduled for field work, Drons is only getting started with identifications, but already he has discovered three state records, one being a species of the sweat bee genus Lasioglossum that was previously undocumented east of the Rocky Mountains. Drons has also gathered precise “locality information” for other species that scientists knew had previously been found in South Dakota, though vague records don’t show where.

“I am just starting the identification process, and will surely have more records and findings with time,” Drons said.

As this summer’s temperatures heat up, Drons will move into the higher elevations where flowers are in bloom. And in the spring of 2011 he’ll be back to do it all over again, covering as many habitat types as possible. He uses a butterfly net in addition to the traps as he combs two or three sites a day.

“It is an inventory, so I need to get to many sites spread across the Hills, representing the dominant habitat types — sagebrush, ponderosa meadows, low density ponderosa forest, more boreal type sites in the northern Hills, rock outcrops,” Drons said. “The goal of having so many sites is to properly sample the habitat diversity.”

A grant of nearly $50,000 from the South Dakota Department of Game, Fish and Parks is funding part of the cost of the three-year study. It’s a project of the Severin-McDaniel Insect Research Collection at SDSU through its Dakota Biodiversity Program. More information about the project is available at an SDSU website, http://nathist.sdstate.edu/BlackHillsBees.html.

The project includes a “citizen scientist” component. Details at the website tell how volunteers can submit photos and specimens of Black Hills bees and provides details on how to collect bees. The study doesn’t include wasps and hornets — only bees.

“Our knowledge base right now is so poor that we know there are more species out there than have been formally reported,” Johnson said. “Very simply we want to find out what species are there currently, what habitats they occur in, and in the case of those that are regular flower visitors and are pollinators on a regular basis, then to ascertain which flowering plants they visit or which ones they seem to prefer at different times of the year — the focus being on which species are out there.”

Knowing what species of bees are there and what plants they are visiting will help biologists better understand the entire Black Hills ecosystem. Johnson said at least 75 to 80 percent of the flowering plants in the Black Hills are dependent on bees or some other species of insect for pollination, or the transfer of pollen from the male flower parts to the female flower parts.

He added that bees are important as “bioindicators” of the health of a region — if they’re doing well, it’s a pretty good sign that the entire Black Hills region is doing well.

“You can use the diversity of the bees in an area as a relatively easy-to-sample proxy for the condition, the overall quality, of those habitats,” Johnson said. “If certain bees disappear, it’s an indication that something is wrong.”

Drons said that’s why it’s imperative to document what species are found in the Black Hills.

“We don’t know fully what’s here,” Drons said. “If you don’t know what’s here, how can you know what’s missing?”

A related SDSU project in collaboration with the Xerces Society for Invertebrate Conservation will be publication of a pocket guide to the bumblebees of the Black Hills.

Drons, who earned his undergraduate degree in biology at Western State College of Colorado in Gunnison, said it was partly the attraction of having the entire Black Hills as his study area that drew him to SDSU to work as Johnson’s graduate research assistant on the bees project. He’s working toward his master’s degree in entomology at SDSU.

Johnson said because the study area covers the entire Black Hills eco-region, it will include the surrounding prairie and the Bear Lodge Mountains in neighboring Wyoming. Drons is gathering voucher specimens and recording detailed information about where and when they were collected. Part of the problem with existing information, Johnson said, is that it sometimes doesn’t give biologists enough information about whether a specimen came from higher elevations in the Black Hills, or from down at the edge of the prairie. That doesn’t tell much about the plant communities a species of bee is using.

“It’s the habitat associations and the flower associations that are critical for putting the whole story together and understanding the dynamics of the environmental changes in the Black Hills using the bees as proxies,” Johnson said.

Jeanne Jones Manzer | Quelle: Newswise Science News
Weitere Informationen: www.sdstate.edu

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