Should we breed crop-specific bees?

As part of the Plan Bee program, research has been undertaken to determine the feasibility of breeding bees for specific crops including alfalfa, apples, avocado and sunflowers.

This has been done by selecting colonies that collected a greater proportion of pollen from the target crop (alfalfa, apple, sunflower). Unfortunately, some of these programs resulted in stock with low brood viability and poor winter survival, and the stock was ultimately abandoned.

However, the mechanism for avocados is different. Avocados have protogynous dichogamy – male and female flowers open at different times of day. Avocados are therefore best pollinated by nectar foragers as they are more likely to move between flowers producing pollen and those producing nectar.

With this in mind, researchers selected for colonies with increased avocado nectar foraging by measuring the amount of perseitol in honey. Perseitol is a hydrocarbon unique to avocados, so high perseitol measures indicate that the colony has been foraging heavily on avocados.

There are drawbacks to selecting bee stock for a single crop. Crops are only available for a small portion of the year, and thus the bees need to be versatile to forage on a range of plants. Moreover, if the crop in question has any nutrient deficiencies, this will have an impact on the health of the hive and reduce its ability to perform pollination services.

Another strategy has been to select bees with a short foraging range. This will limit the ability of bees to fly to alternative forage surrounding the focal crop, and thus improve crop pollination. However, flight range is also influenced by the attractiveness of the crop and the alternate forage. This strategy can have knock-on effects when colonies are not on pollination contracts. It could lead to over-stocking if there is not an abundance of food nearby, which would cause reduced honey production, but potentially colony death.

As with humans, a varied diet improves bee health. Long-term foraging on a single floral source will result in poor health due to nutrient deficiencies. Selection of traits that benefit both beekeepers and growers is likely to lead to better outcomes for both parties.

Strong, healthy colonies perform more foraging trips, and are therefore better for pollination and honey production. A focus on colony management and selection of traits that reduce disease and keep colonies strong and productive will help to ensure that our busy bees continue to provide the pollination services that help keep us all fed.