Ecology and economics of using native managed bees for almond pollination

Authors: KOH, INSU - University Of Vermont; LONSDORF, ERIC - University Of Minnesota; ARTZ, DEREK - Former ARS Employee; Pitts Singer, Theresa; RICKETTS, TAYLOR - University Of Minnesota

Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/25/2017
Publication Date: 12/19/2017
Citation: Koh, I., Lonsdorf, E.V., Artz, D.R., Pitts-Singer, T., Ricketts, T.H. 2017. Ecology and economics of using native managed bees for almond pollination. Ecological Applications. 111(1):16-25. https://doi.org/10.1093/jee/tox318.
DOI: https://doi.org/10.1093/jee/tox318

Interpretive Summary: Evidence of the effectiveness of using managed native bees, instead of or with honey bees, in crop pollination is increasing. However, a broader ecological economic framework for evaluating the costs and benefits of using these bees has not been developed. We conducted a cost-benefit analysis to show how management decisions regarding the cavity-nesting blue orchard bees (Osmia lignaria) in the presence of commonly used honey bees (Apis mellifera) influence growers’ net profit in a California almond orchard. Specifically, we studied how three management options, (1) number of bees, (2) number of artificial nest sites (boxes), and (3) numbers of nest cavities (tubes) per box, influence net profit. To support grower’s decisions, we developed an ecological model of almond yield using published data and estimated net profit according to different management scenarios of supplementing blue orchard bees with honey bees. Estimated annual net profit varied from $2,700 to $7,200 per acre depending on decisions made for all three management options. We predicted that increasing blue orchard bee nest box density only (from three to ten boxes per acre) increased average net profits by $2,400 per acre. Increasing nest box density is critical because of the short distance that blue orchard bees fly and how far they go to find nest sites (boxes for sheltering nesting tubes). Adding additional blue orchard bees and tubes also increased the net profits, but did not show a stronger return than managing nest box density alone. These results show that growers could increase benefit just by providing more nest sites in orchards. If this simple management decision were implemented on 890,000 million acres of almond in California, then the increased net profit could be equivalent to 40% of current annual gross value of California almond production ($6,050 per acre in 2015). Our ecological economic framework supports growers’ management decision-making process and highlights the value of using a more complete ecological economic framework for integration of native managed bees with honey bees in an orchard system.

Technical Abstract: Evidence of the efficacy of using managed native bees, rather than or concurrently with honey bees, in crop pollination is increasing. However, a broader ecological economic framework for evaluating the costs and benefits of using these bees has not been developed. We conducted a cost-benefit analysis to show how management decisions regarding the cavity-nesting blue orchard bees (Osmia lignaria) in the presences of commonly used honey bees (Apis mellifera) influence growers’ net profit in a California almond orchard. Specifically, we studied how three management options, (1) number of bees, (2) number of artificial nest sites (boxes), and (3) numbers of nest cavities (tubes) per box, influence net profit. To support grower’s decisions, we developed an ecological model of almond yield using published data and estimated net profit according to different management scenarios of supplementing O. lignaria with A. mellifera. The model explained 17% of the variance of almond yields. Estimated annual net profit varied from $2,700 to $7,200 per acre depending on decisions made for all three management options. We predicted that increasing O. lignaria nest box density only (from three to ten boxes per acre) increased average net profits by $2,400 per acre. Increasing nest box density is critical because of the short-foraging distance and nest-seeking behavior of O. lignaria. Adding more O. lignaria bees and tubes also increased the net profits, but did not show a stronger return than managing nest box density alone. These results show that growers could increase benefit just by providing more nest sites (i.e., boxes) in orchards. If this simple management decision were implemented on 890,000 million acres of almond in California, then the increased net profit could be equivalent to 40% of current annual gross value of California almond production ($6,050 per acre in 2015). Our ecological economic framework supports growers’ management decision-making process and highlights the value of using a more comprehensive ecological economic framework for integration of alternative native managed bees in an orchard system.