Native Bees, Honeybees, and Pollination in Oregon Cranberries

Abstract

<jats:p>Cultivated cranberry (<jats:italic>Vaccinium macrocarpon</jats:italic> Aiton) relies on insect pollination for berry production. Honeybees (<jats:italic>Apis mellifera</jats:italic> L.) have historically provided this service, but their recent decline has underscored the need for additional pollinators. The objective of this study was to determine the richness and abundance of native bees in the cranberry-growing area of southern coastal Oregon and compare foraging behaviors of honeybees and native bees. In a 2-year study, we collected over 27 native bee species in traps set out during and after bloom (mid-May to mid-June). During 67 2-min observations, honeybees (68.1%) and three species of bumble bees (<jats:italic>Bombus</jats:italic> spp.; 31.6%) comprised 99.7% of foragers. The dominant bumble bee was <jats:italic>Bombus vosnesenskii</jats:italic> Radoszkowski (56.0%). Multivariate regression of temperature and wind speed data indicated that both were significantly predictive of honeybee and bumble bee foragers (<jats:italic>P</jats:italic> &lt; 0.001). The interquartile range for foraging was 18.3 to 22.2 °C for bumble bees and 21.1 to 26.7 °C for honeybees. Over 75% of honeybees were seen foraging above the average observed temperature (19.5 °C). Bumble bee pollen loads had a greater dry mass (6.8 ± 12.9 mg) than those of honeybees (2.0 ± 3.6 mg; <jats:italic>P</jats:italic> &lt; 0.001), and the latter were observed collecting nectar but no pollen more often (during 37.2% of visits) than bumble bees (11.3% of visits). Based on our results, bumble bees in general, and <jats:italic>B. vosnesenskii</jats:italic> in particular, may be providing significant pollination services for Oregon cranberry farms. However, to maintain current native bumble bee populations, conservation efforts are recommended.</jats:p>

Bumble Bee Fauna of Palouse Prairie: Survey of Native Bee Pollinators in a Fragmented Ecosystem

“…Its absence mirrors recent surveys that found a broad geographic decline in the species across the western USA (Cameron et al 2011). In fact, the most recent historical record for B. occidentalis on the Palouse is from 1977, indicating a long absence of this previously abundant bumble bee (National Pollinating Insect Database 2011).…”

“…Bumble bee species can thrive in agroecosystems that offer flowering crops and nesting sites (Carvell et al 2007; Broussard et al 2011), and some open grassland species are adept at utilizing the small-scale resource elements that agricultural matrices provide (Diekötter et al 2006). Local bumble bee communities could be sustained by the agricultural matrix, as evidenced by the higher diversity metrics seen in the lower-elevation remnants.…”

A global review of arthropod-mediated ecosystem-services in Vaccinium berry agroecosystems

“…The number of available managed hives has decreased with recent dareats to honey bee health such as Colony Collapse Disorder and as a result, alternative pollinators are needed for pollination services in agroecosystems (Broussard et al, 2011). For instance, cranberry growers once relied solely on native bees for pollination, many of which are evolutionarily adapted to pollinate cranberry.…”

“…Pollination with managed honey bees and open field pollination with native bees gave similar crop yields, but the average berry size was one-third bigger than in the greenhouse, both with managed honey bees and with native pollinators from the wild. Broussard et al (2011) completed a two-year survey in which they determined the richness and abundance of native bees in the cranberry-growing area of southern coastal Oregon (USA) and compared the foraging behavior of honey bees and native bees. Twenty-seven species of native bees were collected during bloom.…”

“…Five of these species were determined to play a role in cranberry pollination based on visual observations of foraging. Native bees, which, over time, have adapted to the cold, humid coastal conditions, have the potential to be superior pollinators (Broussard et al, 2011). With the current abundance of native bumble bees In Oregon, growers may be able to reduce their dependency on honey bees for pollination and thereby grow the crop more economically.…”