Honeybee Numbers Don't Guarantee Apple Harvests

While many orchard owners rely on honeybees for pollination, a closer look reveals their limited impact on apple harvests. Research indicates that the relationship between honeybee density and apple yield is weak and statistically unproven. Doubling the number of worker bees in an orchard doesn't translate to a doubled harvest; the yield remains largely the same. This might come as a surprise to those who have invested heavily in honeybee colonies, believing them to be the key to a bountiful crop.

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The relationship between the density of the honeybee and the yield of apples is small and statistically unproven.

The real heroes of apple pollination appear to be solitary bees. Unlike their honeybee counterparts, solitary bees significantly boost apple yields, and even improve the symmetry of the fruit. This is despite honeybees often outnumbering solitary bees in commercial orchards. The difference lies in their pollination technique. Solitary bees, in their quest for nectar and pollen, intentionally contact both pollen and stigma, ensuring effective pollination. Honeybees, on the other hand, can be less efficient; some worker bees focus solely on nectar, treating pollen as contamination, and may even avoid pollen contact altogether. Experienced honeybees, paradoxically, become even better at avoiding pollen, thus reducing their pollination effectiveness.

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If you have double the density of worker bees in your orchard, you do not have double the harvest, but essentially the same.

The cross-pollination needs of apple trees add another layer of complexity. For fruit to develop, a flower must be pollinated by pollen from a different, compatible variety. This means bees must travel between trees of different varieties. While bees move between flowers on the same tree, or between trees of the same variety, the crucial cross-pollination occurs when they move between different blocks of apple varieties. This journey is essential for ensuring all ovules within a flower are fertilized, leading to well-shaped apples. The effectiveness of this process is directly linked to the bee's behavior and its ability to transfer pollen from one compatible tree to another.

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For the density of solitary bees, this relationship holds true; double density leads to a higher (though not double) yield of apples, and the fruits even have a more symmetrical shape.