DOE OSTI2018
Pollinators (animals that facilitate plant reproduction by moving pollen from flower to flower) are vital to the health of the world’s ecosystems (Potts et al. 2010). Insects are the most common type of pollinator throughout the majority of the world. The mutualistic relationship of plants and pollinating insects has evolved on every continent from Antarctica to Australia (Kevan 1972, Potts et al. 2010). By enabling successful plant reproduction, pollinating insects support the health of nearly all other organisms in the environment that rely on healthy plant populations for food and shelter. Of the insect pollinators, bees are the most important group of pollinators worldwide (Kearns et al. 1998, Michener 2007). Within the last century, rapid declines in both wild and managed bee populations have been recorded throughout the world (Kearns et al. 1998, Goulson et al. 2005, Biesmeijer et al. 2006). Bee declines are believed to be caused by a combination of stressors including habitat loss, pesticide use, and disease (Cane and Tepedino 2001, Furst et al. 2014). Habitat loss and fragmentation are major causes of bee population declines, especially for wild bees as they rely on flowering plants for forage and nesting (Potts et al. 2010, Winfree et al. 2009). Wild bees can have maximum foraging ranges as small as 150 m, making local habitat structure especially important (Gathmann and Tscharntke 2002). When humans remove native vegetation from the environment they are removing valuable bee food and nesting resources and are contributing to habitat loss and fragmentation, which negatively affects bee populations (Biesmeijer et al. 2006). The greatest abundance of wild bees is suspected to be in semi-desert, arid environments, especially within western North America (Linsley 1958, Koh et al. 2016). This habitat classification matches the environment of the Hanford Site and surrounding Columbia River Basin, suggesting the Hanford Site may have abundant wild bee populations. Native bees are the primary insect pollinators of the Columbia River Basin (Tepedino and Griswold 1995). Although butterflies and moths play a role in pollination in the Columbia River Basin, they are much less efficient at transferring pollen and tend to visit flowering species only for nectar (Tepedino and Griswold 1995). Many species of native bees, honey bees, bumble bees, and butterflies have been documented on the Hanford Site (see Zack 1997); however, pollination-specific studies focusing on Hanford Site insects are uncommon. Over 600 species of bee are known to occur in this region, with the actual number believed to be much higher due to under sampling (Tepedino and Griswold 1995; Niwa et al. 2001). Arid lands of western North America have high proportions of specialized bees that are typically restricted to small geographic areas, making the Hanford Site and the surrounding region especially vulnerable to species loss when habitats are removed (Tepedino 1979).
54 ENVIRONMENTAL SCIENCES↗