Factors to Consider when Determining Honeybee Hive Needs for Almond Orchards

Honeybee hives placed within an almond orchard.

Determining the number of hives to rent for an almond orchard can be challenging. With a strong reliance on honeybees for pollination, placing too low of number of hives and bees can reduce crop potential, especially in inclement weather, while placing too many increases operational expenses. To determine the proper hive strength for the almond orchard, the following factors should be considered:

1. Varieties present within the orchard
2. Age of the orchard
3. Strength of the hives contracted
4. Crop insurance requirements
5. Anticipated weather for the orchard’s production area;
6. Presence of other pollinators.

Almond Varieties within the orchard. All almond varieties benefit from having pollinators present during bloom. In California and Australia, the primary varieties planted are ‘Nonpareil’ and the selected compatible, pollinating varieties. Since these varieties, as well as others (e.g.'Butte'/'Padre'), require cross-pollination to set a nut, bees are required to maximize orchard yields. Due to the requirement for cross-pollination, the recommendation by the University of California has been to place two 6-8 frame hives per acre (5 hives per ha) to maximize pollination (Micke, 1996).

In Europe and more recently in California and Australia, self-pollinating almond varieties are present. These varieties do not require pollen from a compatible variety to fertilize the flower. In these orchards, bees are not required to set a commercial crop, but they have shown to increase yields. In Europe, studies have shown yield increases between 5-20% amongst European varieties. In California, the presence of honeybees has shown to increase yield by 20% or more within ‘Independence’ (Saez, et al, 2020).  These studies indicate that bees should be placed to optimize pollination, but suggest that the number of hives per acre can be fewer. In Europe, 1-1.25 hives/acre (2-3 hives/ha) are common stocking rates within orchards that utilize bees. This may be a reasonable range to consider for California’s self-fertile varieties.

Orchard age. The age of the orchard influences the honeybee requirement due to the differing number of flowers that need to be visited. It is common practice to place fewer beehives than mature orchards during the 3^rd and 4^th growing season (1^st and 2^nd harvest) to account for the developing tree size. Observations of various operations indicate stocking rates of 1-1.5 hives/acre the first harvest year, and 1.5-1.8 hives per acre for the second year of harvest (typically the 3rd and 4th year, respectively). It should be noted that operations in which these observations were made utilized 6-8 frame hives.

Hive strength. Hive strength is probably the most overlooked aspect by almond operations. This has a lot to do with the guidance of “two hives per acre.” Research from as early as the 1970’s has shown that stronger hives (i.e. more frames) collect more pollen. More recently, an analysis of pollination requirements has shown that stronger hives may reduce the number of hives per acre. Goodrich and Goodhue (2016) have shown that as colony strength increases above 8 frames/hive, the beehive requirement to achieve the same rate of pollination drops. This means the number of hives per acre can be reduced if the hives contain 8 frames or more. They suggest that pollination should be based on a minimum frame count rather than a set number of hives. Their article suggests that somewhere between 12-14 frames with 75% of the frame populated by bees within 1-2 hives be utilized per acre.  As such, contracting stronger hives may reduce the hive requirement per acre. It should also be noted that stronger hives typically have more activity at lower temperature ranges.

Crop Insurance Requirements. Most crop insurance requires that honeybees be placed within an orchard. If utilizing crop insurance, make sure to meet the requirement listed to provide the foundation for a potential future claim.

Anticipated Weather During Bloom. Wet, cold weather reduces the number of hours bees are active. This is due to multiple factors including difficulty for bees to fly, reduced pollen availability due to pollen being washed off the flower, and the requirement for the hive to maintain a temperature range. Therefore, bees tend to be most active on calm days with temperatures above 55°F (~12°C). If in an area that has an increased risk of rain or cold weather during bloom, a higher number of hives should be considered per acre. For further illustration, the number of hives/frames within an orchard located near Chico, CA should be greater than the amount placed within an orchard near Bakersfield. Even so, placing too few hives in an area that typically has good weather through bloom has a risk if the weather turns wet and cold.

Presence of Other Pollinators. Research has shown that the presence of other pollinators improves bee visits and pollen foraging. This would suggest that beehives could be reduced per acre if utilizing bumblebees, blue orchard bees, or other pollinators. Recommendations on reductions, however, are not very clear. Stocking alternative pollinators does seem to help improve pollination during inclement weather, but no differences were observed when good weather persisted through bloom (Dag and Zipori, 2016). Due to the mixed results, it may be best to consider the addition of other pollinators as an added bonus, and not as a replacement for honeybees.

With the downturn in pricing, reducing operational expenses will help maintain an economically sustainable operation. Since pollination services are a primary expense within many orchard operations, it may be tempting to reduce this budgeted line item. Cutting down on the number of hives requires careful consideration since pollination is a primary driver in the orchard’s yield potential.  If wanting to reduce pollination costs, consider the various factors listed above to determine a site-specific hive recommendation. It may be possible to modify the hive/frame requirement and corresponding pollination services contract to achieve an operational savings without impacting pollination.

Works referenced:

• Connell, J.H. “Pollination of almonds: practices and problems.” Hortechnology 10(1) (2000):116-119.
• Dag, A. I. Zipori. “Using bumblebees to improve almond pollination by the honeybee.” Journal of Apicultural Research 45(3) (2016):215-216.
• Henselek, Y. et al. “Pollination requirement of almond (Prunis dulcis): combinaing laboratory and field experiments.” Journal of Economic Entomology XX(X) (2018):1-8.
• Goodrich, Brittney and Rachael E. Goodhue. “Honey Bee Colony Strength in the California Almond Pollination Market.” ARE Update 19(4) (2016): 5-8. University of California Giannini Foundation of Agricultural Economics.
• Sáez, A., Aizen, M.A., Medici, S. et al. Bees increase crop yield in an alleged pollinator-independent almond variety. Sci Rep 10, 3177 (2020). https://doi.org/10.1038/s41598-020-59995-0
• Sheesley, B. & Poduska, B. “Strong Honeybee Colonies Prove Value in Almond Pollination.” California Agriculture, 24(8) (1970): 5-6. https://ucanr.edu/repositoryfiles/ca2408p5-63783.pdf.
• Warren, Micke. “Almond Production Manual.” University of California Agricultural and Natural Resources (1996). Oakland, CA USA.