Project objectives from proposal:
The main goal of the study is to evaluate the potential of native bee habitat enrichment to boost native bee abundances of previously identified target bee species, as well as provide farmers with a supplemental income source.
The secondary goal is to continue surveying native bees for a sixth year within the apple orchards, with a focus specifically on the apple bloom periods. Significant weather changes, perhaps due to global warming, have resulted in drastically different growing seasons during the past 5 years. The apple bloom shifted 4-5 weeks earlier during the past 2-3 years, occurring in March. Last year the weather shifted back to the typical bloom in April. Native bees abundance and diversity significantly varied during these blooms. These much earlier apple blooms can impact which native bees are present to pollinate the flowers (e.g. mason bees, Osmia species, are more important during early apple blooms).
MAIN GOAL – Evaluate the potential of native bee habitat enrichments
To achieve the main goal, experiments will be performed at three North Georgia apple orchards. In these orchards, habitat enrichment areas tailored specifically to the target Apple-pollinating native bees will be set up. Two groups of native bees will be targeted: mason bees (Osmia species) and mining bees (Andrena species).
Mason bees such as Osmia georgica and O. taurus (two species identified with great potential in Georgia apple orchards) require nesting tubes, since they are plant stem cavity nesters in nature. Mining bees such as Andrena crataegi (species with the greatest potential to replace the honeybee) prefer patches of soil in which to dig tunnels for their habitat and a place to brood their young.
After some field experimentation, the following design will be implemented: a series of four bee houses with three soil trenches (12 inches wide X 30 long x 12 inches deep) placed in between each bee house. Each bee house will contain 40 different sized nesting tubes (6mm, 7mm, 8mm diameter).
Mountain View and Tiger Mountain Orchards will have four enrichment areas. Mercier Orchard will have two enrichment areas. In addition, half of the enrichment areas will have flowering fruit trees (cherry, pear, etc.). It is hypothesized that flowering fruit trees will lure mason and mining bees to enrichment areas, since no other plants are flowering at this time of year.
Enrichment areas offer mason bees nesting habitat and materials. Mason bees require mud to cap off and separate each cell in their nesting tubes. Excavated soil from trenches will be placed around the base of the bee houses. Enrichment areas with flowering fruit trees also offer an early food source. Based on last year’s preliminary study, Osmia georgica prefer 6 mm tubes and O. Taurus prefer 8 mm tubes. During our 5-year native bee survey, we found more than 10 different Osmia species in Georgia apple orchards. In order to assess the success of the nesting tubes for boosting the abundance of the mason bees, we will examine each individual tube to get an exact count of the Osmia. This type of examination does not hurt or injure bees. Most of these bees will be returned back to their originating orchard. Some larvae will be raised to adulthood in order to identify their species.
Enrichment areas offer mining bees nesting habitat. Excavated soil will be placed on one side of the trench to create a hill effect. The larger, bare soil hill is believed to attract mining bees to the enrichment area. Mining bees prefer patches of bare soil in which to dig tunnels for their habitat and a place to brood their young. Enrichment areas with flowering fruit trees also offer an early food source. In order to assess the success of the soil enrichment areas for boosting the abundance of mining bees, we will examine the soil for holes (entrances to the colony). We will excavate some areas of the soil to measure larvae abundance.
SECONDARY GOAL – Survey of Native Bees in Georgia Apple Orchards
To achieve the secondary goal, a survey of native bees will be conducted in four North Georgia Apple Orchards.
In these orchards, native bees will be collected using several types of insect collecting traps and procedures, including pan-traps, malaise-traps, and timed sweep-netting. Insect diversity and abundance will be measured 2 weeks prior to and after the bloom, and weekly during the bloom itself. The traps will be set up around dawn and will remain up until after dusk during collection days, which is a typical 12-hour collection period. Approximately, 10-12 collections will be made at each orchard during the growing season.
At each orchard, there will be a total of 13 sets of pan-traps. Each set includes 1 white, yellow, and blue pan painted with UV-reactive paint. Likewise, 2 malaise traps will be set-up (1 trap in the center and the other trap near the edge of the plot) for each sample day. Active collection methods, such as 1-hour timed sweep netting, will also be performed at each orchard during each sampling day.
After the collection, the bees will be brought back to the GGC laboratory to be counted and identified. Bees will be determined to species, pinned, and mounted in permanent collection boxes. Species will be compared to reference collections at the USGS Bee Inventory and Monitoring Lab.