Our study aims to investigate the role of landscape composition in contaminant exposure by pollinators, specifically the European honey bee (Apis mellifera) and the common eastern bumble bee (Bombus impatiens). By analyzing pesticides found on the worker bees foraging in urban, rural, and suburban landscapes we hope to understand how the Ohio landscapes in which these bees forage influence their likelihood of contamination. Both analyses of pesticide types/concentrations found in bees and landscape analyses are ongoing. Bumble bee samples were found to be unresponsive to pesticide analysis, and to ensure use of these samples we are investigating additional contaminants, heavy metals. Preliminary results show bumble bees are exposed to a variety of heavy metals in rural, suburban, and urban environments. Workers exhibited significantly less levels of cadmium, copper, and lead as distance from the urban center of Cleveland, OH increased. Additionally, levels of cadmium, copper, lead and zinc present in worker bees significantly correlated with decreased larvae present in the colony after three weeks of exposure. Objectives 1 and 2 of our study should be completed in 2016.
Over the last decade pesticide exposure has been cited as a probable factor contributing to global bee decline (Goulson et al. 2008). In fact, neonicitinoid pesticides such as imidacloprid have been banned from use in Europe starting in 2013 due to concern over their negative impacts on honey bees, particularly their role in Colony Collapse Disorder, or CCD (McDonald-Wilson 2013, Schmuck et al. 2001). However, while there has been some evidence of pesticide exposure incurred by honey bee hives of large-scale beekeeping operations, there is as yet virtually no evidence that the risks are similar for smaller-scale operations like those often providing honey bee hives to fruit and vegetable growers in the north central region (Mullin et al 2010). Additionally, there has been no evidence as to what pesticides bumble bees and other bees native to Ohio are exposed to in their natural foraging environments. These native pollinators provide significant pollination to fruit and vegetable crops as well as non-crop plants, contributing the majority of pollination services in some systems (Greenleaf et al. 2007). Ohio produces vegetable and fruit crops valued at over 135.4 and 45.4 million dollars per year, respectively, which benefit from pollination services rendered by managed and non-managed bees alike (NASS 2007).Our study will be the first to detail the types and concentrations of pesticides encountered by foraging honey bees from small-scale beekeeping operations, as well as the first to document the pesticides encountered by foraging bumble bees of any species worldwide. We will also conduct the first investigation into landscape composition as a predictor of pesticide exposure. In doing so, this research will not only prove invaluable to the sustainable pollination of crops in Ohio and the north central region by identifying risks to pollinator health and function, but it will also investigate a possible mechanism influencing these risks. This study will contribute to NCR-SARE’s broad-based goals by providing beekeepers, fruit and vegetable growers, and extension agents with information regarding the effects of pesticide management practices on pollinators. This information will prove useful in encouraging best management practices and enhancing environmental quality in agroecosystems.
We expect analysis of pesticide contamination to be completed by September 1, 2016 (Obj. 1). Preliminary landscape analysis (minus inclusion of contamination data) is complete (Obj. 2). Heavy metal analysis is complete, and we are currently working on data analysis and paper publication. We expect to have at least one publication ready by the end of 2016, with the possibility of two.
Objective 1 methods: To evaluate the diversity and concentration of influence of pesticides on foraging honey bees we utilized an established citizen science program, “Bee Healthy Landscapes,” managed by our lab. This program provided 20 beekeeper collaborators with a tool kit including sampling instructions, a data sheet, vials, collecting tools, and a pre-paid mailing box. Each beekeeper collected samples of honey, wax and workers from one hive following provided instructions and sent them to us along with information about the hive including the GPS coordinates or nearest crossroads for its location, how long the hive has been present at the current location, age of the colony, number of hives at location, purpose of the colony, any problems they have had with the colony, and if available known spray records for farm site (for hives supplied for crop pollination services).
To evaluate the diversity and concentration of influence of pesticides/heavy metals on foraging bumble bees, we allowed bees to forage within the landscape surrounding their release site (N=30) for 21 days. Subsequently the bumble bee hives were collected and frozen (-80°C). I took several measures of bee health including (but not limited to) nest weight and number of offspring present. A total of 50 were randomly selected from each hive for pesticide content analysis.
Honey bee are currently being assayed for 300 pesticides including insecticides, fungicides and herbicides. The analysis will be conducted using the QuEChERS method (so named because it is considered Quick, Easy, Cheap, Effective, Rugged, and Safe). This method uses dispersive solid-phase extraction (d-SPE) of acetonitrile extracts to simultaneously isolate a wide range of insecticides, fungicides, and herbicides from the sample matrix. This analysis will be conducted under the guidance of Dr. P. Larry Phelan. Heavy metal analysis was conducted at the STAR Lab of the OARDC (Wooster, OH). Homogenized bee samples were digested in perchloric acid before samples were analyzed in a spectrophotometer.
Objective 2 methods: We have quantified the landscape surrounding each hive at a radius of 3 miles, the estimated foraging range of A. mellifera and B. impatiens. Using ARC GIS 9.3 a landscape buffer (3 mile radius) was created surrounding each GPS point location of a hive and all habitats within the buffer were digitized so that their area can be determined. All land cover that is planted or growing within all areas of the buffer circle will be classified by on-the-ground verification. We will then determine the proportion of each buffer composed of each of the land cover classes recorded. The heterogeneity of each landscape will be determined using the Simpson’s Diversity Index (D). An Akaike’s Information Criterion (AIC) will be used to evaluate regression models relating the diversity and concentration of pesticides in hive samples to landscape heterogeneity (D) and landscape composition. Heavy metal comparison along the landscape gradient was analyzed using distance from city center and percent impervious surface data.
All bee samples are now collected and prepared for chemical/elemental analysis. Honey bee worker and provision analysis for pesticides is currently underway. Bumble bee worker and provision analysis for heavy metals is complete (2015). Preliminary analysis shows that bumble bee workers are indeed capturing numerous heavy metals from their environments, including lead, cadmium, chromium, mercury, and arsenic. Concentration of metals within worker bees (ug metal/g tissue) significantly decreased with distance from the urban center of Cleveland for copper (p=.041; r²=.061), cadmium (p<.001; r²=221), and lead (p=.002; r²=.097). The number of larvae present in colonies after three weeks of environmental exposure significantly decreased with metal concentration for cadmium (p=.001; r²=.349), copper (p=.027; r²=.161), lead (p=.021; r²=.178), and zinc (p=.042; r²=.132). Landscape data has all been collected and has been analyzed for all sites.
Educational & Outreach Activities
Data analysis is currently incomplete and so publications and outreach events have not been completed. As stated above we plan at least 2 publications from this research, as well as various outreach events involving growers, beekeepers, and master gardeners.
This study will contribute to NCR-SARE’s broad-based goals by providing beekeepers, fruit and vegetable growers, and extension agents with information regarding the effects of pesticide management practices on pollinators. This information will prove useful in encouraging best management practices and enhancing environmental quality in agroecosystems. We look forward to disseminating the results of our studies to volunteer beekeepers and homeowners, extension agents, and the scientific community.
As data is not yet completed we have no data on farmer adoption.
Areas needing additional study
Both pesticide and heavy metal exposure of bumble bees/ honey bees represent patterns of exposure across a urbanization gradient. Further studies should determine actual exposure levels accrued by bees throughout the growing season. This will prove difficult without removing considerable amounts of bees from the natural populations, however commercially available bees (as used here) and noninvasive sentinel practices can be used to avoid this. Secondly, numerous laboratory experiments will need to be completed to confirm/expand upon our results. Investigating known percentages of contaminants on bee colony growth and success will be crucial in understanding our results’ true impacts.