Virginia Orchard IPPM: Native wildflower plot to provide alternative forage, habitat, and refuge for bee pollinators

At the WAREC in Northern Virginia, a ½ acre wildflower plot was established in 2021 through collaboration between the USDA Natural Resources Conservation Service (NRCS), WAREC staff, and the Virginia Department of Agriculture and Consumer Services (VDACS). Wildflower plots provide benefit to bees by providing habitat, dedicated forage, and refuge from pesticide exposure. The WAREC plot is tailored to the needs of this project and specifically to the Shenandoah Valley region of Virginia. Regional specificity in planting is important to increase likelihood of a successful establishment, reduce the need for additional watering or care, and avoid the introduction of non-native invasive species. The native seed mix contains one annual and 21 perennials. By favoring perennials in the mix, the plants will be able to subsist for a few years, depending on the species, and will typically build in vigor with successive years. Eventually, the original species composition will begin to degrade, but this plot is not expected to begin experiencing major fluctuations in annual composition for 5-10 years depending on a range of biotic and abiotic factors. The wildflower seed mix for this plot was selected with the intention of providing blooming flowers throughout the growing season, with a particular focus on the apple post bloom period. The plot is expected to reach peak maturity in the summer of 2024. The WAREC staff manages the wildflower plot and provides general maintenance and upkeep.

Methods for Objective 1

Understanding Apis mellifera forage data requires the decoding and mapping of a unique form of temporo-spatial honey bee communication called the waggle dance. This dance is conducted when a non-reproductive female, known as a worker, returns from her foraging trip and decides to share information about her foraging success. She enters the hive and, while clinging to the comb vertically in near-total darkness, relays coded information in the form of a waggle dance to her sister foragers. The duration of the waggle phase of the dance encodes an amount of distance away from the hive (approximately 750m/1sec dance duration). The dance angle, where vertical “up” on the vertically oriented comb is equated to the direction of the sun, dictates the direction of the resource in relation to the sun (measured as 0^o-359^o with 0^o oriented to the direction of the sun on the horizon). This behavioral communication is visible and can be decoded to indicate a probability distribution of when and where the honey bees are foraging across a landscape [7]. Thousands of individual dancing bees are recorded over a study period and their communicated vectors decoded by hand to provide probability distributions which can be then mapped in ArcGIS to provide an indication of where the bees are foraging in the landscape. Because within hive behavioral correlations are rare, each individual dance is considered an independent replicate in our analysis [7].

This research will be accomplished by installing three glass-walled, honey bee observation hives in an already present and optimized research shed located at WAREC. Recording will occur for one hour/day for three days/week from all three hives the waggle dances performed by returning foragers. Dance data (c. 800 dances) will be decoded and mapped utilizing existing methods [8]. These spatial data will then be analyzed and mapped using ArcGIS Pro to determine where the honey bees are foraging in the ~2km radius centered on the hives, and, if their foraging shifts from the post-bloom apple orchards [6] to the wildflower plot as hypothesized. Data will be collected in May, June, and July of 2024 when the wildflower plot is at its peak.

Concurrently with the video recording, pollen will be collected from returning foragers using wire mesh traps set on the entrances to the observation hives. Pollen will be sorted by color and date, which will then be correlated with plant taxa identity. Representative samples will be sent to Cornell University for pesticide residue analysis using a fee-for-service laboratory. Data will be collected in May, June, and July of 2024 when the wildflower plot is at its peak. This new pesticide data will be compared with data previously collected before the wildflower plot was established and may identify if a wildflower plot is effective in reducing honey bee pesticide exposure.

Methods for Objective 2

Non-Apis bees are not known to possess a visible, decodable communication signal, like the honey bee waggle dance, that would indicate their foraging patterns. Instead, the presence of wild bees is typically recorded by destructively sampling to obtain the highest taxonomic resolution. Some of the larger or more striking bees can be identified to species on sight, but many bees require a microscope for accurate identification within an acceptable degree of certainty. Lethal sampling may seem counter-intuitive for pollinator studies; however, the process appears not to significantly impact species richness or abundance [9]. Sampling methods include active sampling with hand nets or passive sampling with pan or bowl traps, vane traps and, less commonly used for bees, malaise and sticky traps. Blue vane traps have been found to be significantly more effective than other colors of pan or vane traps at measuring bee abundance and species richness: blue vane traps solely accounted for 82.2% of the species collected [10].

The proposed research will double the two years of existing non-Apis bee species richness and abundance data at this location with the total research duration spanning 2021-2024. The gradual establishment of the wildflower plot will potentially influence a change in localized bee species richness and abundance. Therefore, sampling at the WAREC will be done using the same methodologies as previously conducted, including monthly destructive sampling in May, June, and July using blue vane traps, tri-colored bee bowls, and hand netting over a period of 48 hours. Hand netting will be conducted along established transects over a standardized duration. The collected specimens will be cleaned, organized, pinned, and later identified to species. Species richness and abundance will be compared between the pre- and post-wildflower plot establishment periods as the plot comes to its peak in 2024.