How climate change may affect insect pollinator populations in the Midwest.Environmental Change Institute UIUCAgroecology and Sustainable Agriculture Program UIUCunpublishednot peer reviewe

Cameron, Sydney A.

Marlin, John C.

English

Illinois Digital Environment for Access to Learning and Scholarship Repository

How Climate Change Will Affect the MidwestNative PollinatorsCope with Environmental ChangeCitizen scientists are members of the public who volun-teer time and effort to gather data needed by scientists. At BeeSpotter, citizen scientists and amateur bee hunters part-ner online with scientists to gather images of bees around Illinois. Each spotting helps illuminate which bees live where. If you would like to help researchers understand and protect bee populations, snap some photos and visit beespotter.mste.uiuc.edu to contribute. Key TermCitizen ScientistUniversity of IllinoisAre Wild Bee Pollinator Populations Declining?Issue 1:8 ref:  http://hdl.handle.net/2142/16449in the state declined substantially in the past century, especially between 1940 and 1960. Four historically recorded species were not found during extensive col-lecting in 2006 and 2007, while four other bumble bees were found in fewer areas of the state.Most bees are solitary and do not associate with their offspring or siblings. They emerge each year and mate, and nest in soil tunnels or in tunnels or cavities found or dug in wood, plant stems, or other material. The females provision cells with pollen and nectar for their young. Some species are active during most of the growing season, while others are active only for a few weeks. They typically die before their offspring emerge.Carlinville, Illinois, is home to one of the oldest and most comprehensive studies of bees ever conducted. Between 1884 and 1916, Charles Robertson collected 296 species on over 400 plants. A re-collection in the area in the early 1970s concentrated on 24 selected plants. University researchers found 82 percent of the bee species originally present on those plants.National concern over honey bee colony collapse has generated interest in the status of the other 3,522 U.S. bee species, most of them wild pollinators. Because bees are the primary pollinators of many flowering plants and important crops, a national decline in overall wild bee popu-lations would seriously affect the economy as well as natural plant communities. European countries have sampled bee pop-ulations for decades and have documented regional declines. Commercial and wild U.S. bee populations have not been sys-tematically monitored, but there is evidence that the ranges and numbers of some species are shrinking.Hundreds of Unique Illinois Bee Species Provide Different Pollination ServicesBumble bees are important wild pollinators, largely due to their robust size, long tongues, flight range, versatility, pollina-tion efficacy, and the number of flowers they use for pollen and nectar. They also engage in “buzz pollination” (the buzz they make while on a flower vibrates the pollen receptacle at the fre-quency to expel the pollen), an important mechanism that honey bees do not exhibit. Bumble bees live in colonies initiated each spring by solitary queens that overwinter from the previous au-tumn. The colonies get bigger as the season progresses.University of Illinois scientists are surveying bumble bees across the U.S. and comparing them with historical records from tens of thousands of museum specimens to track any sig-nificant changes in species richness and distribution over the last 20 years. The Illinois Natural History Survey insect col-lection has about 360,000 Hymenoptera specimens (ants, bees, and wasps) dating from the 1800s to the present. Sixteen of 49 U.S. bumblebee species were historically recorded in Illinois before 1949. A comparison of museum specimens with recent field collections shows that the richness of bumble bee species Change and the HeartlandBig issues, bite-sized lessons          Plant Season Long-tongued bees Short-tongued bees Butter- flies and moths Virginia Bluebell  early spring  16  2  6 Spring Beauty early spring  21  37  9 foxglove beards-tongue  late Spring -summer  17  5  3 Swamp Milkweed summer  12  6  15 Brown-eyed Susan summer  23        25  7 Sawtooth sunflower fall  29  9  13 Aster pilosus fall              37  53  30   Scientific plant name   Plant  Season long‐tongued bees short‐tongued bees Other Hymenoptera Diptera Lepidoptera Mertensia virginica early spring 16  2  0  3  6 Claytonia viginica early spring 21  37  0  5  9 Polemonium reptans  spring 21  17  0  5  5 Cercis canadensis  spring 22  19  1  4  5 Salix interior   spring 16  43  10  47  1 To survive, bees primarily require suitable nesting sites close to a continuous source of pollen and nectar when adults are active. Given their small size, bees can maintain themselves in much smaller areas than larger species like mammals. The bees at Carlinville are probably still pres-ent because some suitable habitat remains, although their overall numbers are likely greatly reduced. Likewise, the resources needed by a large bee or bumble bee colony to successfully reproduce far exceed those of a small solitary spring bee. The situation is further complicated by the fact that some bees, like honey bees, are generalists and use many plants, while others are adapted to obtain pollen and nectar from only a few specific plants. Habitat Fragmentation, Pesticide Use, and Conventional Landscaping Stress Bee PopulationsBees are vulnerable to various modern practices as well as to introduced diseases. Land use and landscaping changes that occurred after World War II greatly impacted many spe-cies. The switch to row crops, removal of fencerows, conver-sion of mixed hay pastures to grasses or green alfalfa, and the advent of roadside herbicide spraying and mowing removed nesting habitat and eliminated useful flowering plants in rural areas. In and around urban areas, new subdivisions are be-gun by scraping away, piling, and often removing topsoil, to-gether with its nesting bees. The new landscaping often lacks plants that provide pollen and nectar throughout the growing season. Extensive pesticide use in soil and on plants also kills countless bees. Bee habitat is becoming increasingly limited and fragmented, forcing bees to live in ever-smaller areas. This isolation, in turn, makes it more difficult for bees to maintain genetic diversity and to recolonize habitats. Climate Change Could Force Bee Populations to Shift; Habitat Fragmentation Could Inhibit the MigrationIf climate change causes shifts in temperature, rainfall, and ultimately the plants that can survive in an area, bee spe-cies that cannot adapt must emigrate to survive. However, bees have a relatively short flight range. Many species would probably be unable to bridge the distances between locations with suitable habitat in much of Illinois and would suffer dra-matic declines. Habitat fragmentation would also make it dif-ficult for species already adapted to new conditions to colo-nize the area. For example, species that currently range from Louisiana to Canada will likely adapt, while species found only in the Southwest may not be able to migrate to Illinois.Planting a Variety of Native Plants Provides Pollinators Food Throughout SeasonNumber of pollinator species that visit each plantEditors:  Michelle Wander (mwander@illinois.edu) John E. Marlin (marlinje@gmail.com)Designers: John E. Marlin, Crystal BartanenCopyeditor: Molly BentsenCopyright © 2010, University of Illinois Board of Trustees. “Change and the Heartland” was developed for the Environmental Change Institute by the Agroecology and Sustainable Agriculture Program, in the College of Agricultural, Consumer and Environmental Sciences at the University of Illinois at Urbana-Champaign. To read the rest of the series, visit eci.illinois.edu.Landscaping with Native Plants and Habitat Corridors Would Help Feed Bees and Aid MigrationsUsing native plants and carefully selected ornamentals in rural areas, along roadsides, and in neig borhoods, parks, and public landscaping would help mitigate the impacts of habitat fragmentation. Creating habitat islands and corridors would provide food for bees and other pollinators as well as many bi ds. Planting on or near suitable nesting sites would be even more helpful. The table  above lists a few of the many plants that together could provide a continuous food resource throughout the growing season. Comprehensive lists of suit-able plants and their availability could be developed for differ-ent parts of Illinois. Highways, rural roads, railroads, streams, and related land could form corridors for the migration and dispersal of native bees, butterflies, birds, and other animals. About the Researchers Dr. John Marlin is an associate director of the Illinois Sus-tainable Technology Center. Dr. Sydney Cameron is an associate professor in the Department of Entomology and the Program in Ecology, Evolution and Conservation Biology at the University of Illinois.

Are Wild Bee Pollinator Populations Declining?

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