Honey bees (Apis mellifera) may serve as bioindicators of habitat quality for themselves and also other insect pollinators because we can observe, decode, map, and analyze the information encoded in the waggle dance communication behavior, which allows us to know where and when bees are collecting high quality forage. Previously we measured honey bee foraging dynamics for two years (2018-2019) by waggle dance decoding at three geographically distanced sites in Virginia (Blacksburg, Winchester, Suffolk), consisting of different dominant landcover types. Here we use those data on where and when honey bees were finding profitable resources throughout the season to predict the success of a non-Apis bee in these same landscapes.
Alfalfa leafcutting bees (Megachile rotundata) are managed, polylectic, solitary, cavity-nesting bees that are widely naturalized in North America. We selected M. rotundata as a model organism to validate the honey bee foraging data because they share some characteristics with other cavity nesting wild bees, but they are a tractable study system because they are commercially reared and can be purchased for study. At each of the three sites, we installed 15 nest box stations, each stocked with nesting materials and 160 M. rotundata cocoons, at varying distances and directions from the original honey bee hive locations. Most importantly, nest box stations were distributed across a range of honey bee foraging propensities, calculated as the mean foraging probability determined from our honey bee waggle dance decoding data, within a 300m buffer around each nest box. We hypothesized that honey bee foraging probability would positively correlate with M. rotundata cocoon production and survival.
For two years (2021-2022) from May-August, we monitored the nest boxes and also collected data on the relative abundance of floral resources at each of the 15 stations per site. At the end of each season, we collected nesting materials and counted both M. rotundata along with incidental (i.e., non-M. rotundata) wild bee cocoons. M. rotundata cocoon productivity varied by location (log-likelihood ratio test: χ2 = 311.0, df = 2, p < 0.001), with Winchester as the most productive location (mean cocoon count (95% CI): 26.2 (23.7 to 28.9)), followed by Blacksburg (20.4 (18.2 to 22.9)), and Suffolk (4.4 (3.5 to 5.5)). The abundance of clover, both red and white, had a significant positive effect on ALCB productivity (log-likelihood ratio test: χ2 = 778.36, < 0.001). On the other hand, the number of ALCB cocoons decreased significantly with the count of Trypoxylon wasp cocoons present in the nest boxes (log-likelihood ratio test: χ2 = 54.37, < 0.001). Most importantly, we found that there was an overall negative relationship between honey bee foraging probability and alfalfa leafcutting bee cocoon productivity ((log-likelihood ratio test: χ2 = 55.42, < 0.001), where areas of higher honey bee foraging probability were associated with lower levels of alfalfa leafcutting bee productivity. This surprising result is in the opposite direction to our original hypothesis that preferred honey bee foraging areas in the landscape, as indicated by decoded waggle dance data, would be positively correlated with alfalfa leafcutting bee productivity. These data demonstrate that while honey bees may indeed act as bioindicators to other insect pollinators, this indication will likely be species and context specific and may even specify the opposite direction. / Master of Science in Life Sciences / Recent challenges facing the beekeeping industry have laid bare the fragility of honey bee pollination services, highlighted the role of other bee pollinators, and sparked widespread concern over the effect of declining bee populations on food security and continued ecosystem function and services. Both honey bees and wild bees face similar challenges including pesticides, parasites, pests, and poor nutrition from a lack of flowers in the landscape. Therefore, it is critical that we develop methods to evaluate the landscape's ability to feed bees in order to help them and other pollinators continue providing essential pollination services.
There are many ways to measure the quality of a landscape for pollinators, but honey bees offer a unique opportunity to do the work for us: honey bees communicate the location of where they find food to their nestmates through a behavior called the waggle dance. Waggle dances can be observed and the dance language decoded so that we can determine the location of high-quality food sources. Previously, we used honey bee waggle dance data to map where bees are collecting food in three geographically distinct sites (Blacksburg, Winchester, and Suffolk, Virginia). These data allow us to understand where, when, and on what flowers the honey bees were feeding.
The goal of this project was to investigate the relationship between honey bee foraging and non-honey bee success across the same three landscapes to determine if honey bees can be used as bioindicators of habitat quality for other bees. We chose Alfalfa leafcutting bees (Megachile rotundata) as a model organism because they are solitary, cavity-nesting bees, like the majority of wild bees. However, as managed pollinators, Alfalfa leafcutting bees (ALCBs) can be purchased commercially and retained in nesting boxes to allow us to gather productivity and survival data, which we can then compare to what the dancing honey bees previously told us about where and when they can collect good food. We hypothesized that areas of the landscape that honey bees had indicated where higher quality would correlate to better ALCB cocoon production and survival.
We placed wooden nest boxes, 15 per site, stocked with ALCBs across the same landscapes for which honey bee data had been collected in the previous years and measured their productivity in terms of cocoons produced at each site. ALCB productivity varied by location, with Winchester as the most productive location (mean ALCB count (95% CI): 26.2 (23.7 to 28.9)), followed by Blacksburg (20.4 (18.2 to 22.9)), and Suffolk (4.4 (3.5 to 5.5)). The abundance of clover, both red and white, had a significant positive effect on ALCB productivity (log-likelihood ratio test: χ2 = 778.36, < 0.001). On the other hand, the number of ALCB cocoons decreased significantly with the count of a non ALCB nest box resident, Trypoxylon wasp cocoons, present in the nest box (log-likelihood ratio test: χ2 = 54.37, < 0.001). Surprisingly, we found that there was an overall negative relationship between honey bee foraging probability and alfalfa leafcutting bee cocoon production (log-likelihood ratio test: χ2 = 55.42, < 0.001). In this study, across three different field sites with varying landscapes in Virginia, areas of higher honey bee foraging probability were associated with lower levels of alfalfa leafcutting bee productivity.
| Identifer | oai:union.ndltd.org:VTETD/oai:vtechworks.lib.vt.edu:10919/115476 |
| Date | 21 June 2023 |
| Creators | Campbell, Chad Dennis |
| Contributors | Entomology, Couvillon, Margaret J., Wilson, James McKee, Schuerch, Roger |
| Publisher | Virginia Tech |
| Source Sets | Virginia Tech Theses and Dissertation |
| Language | English |
| Detected Language | English |
| Type | Thesis |
| Format | ETD, application/pdf |
| Coverage | Virginia, United States |
| Rights | In Copyright, http://rightsstatements.org/vocab/InC/1.0/ |
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