BERRIES
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Honey bees
can help with better blueberry yield Animal-mediated pollination is an essential ecosystem service on which over a third of the world’s agricultural crops depend. Blueberry fruit production is highly dependent on animal pollination and, although visited by a range of bee species in their native range and agricultural settings, bumble bees are thought to be their primary native pollinators.
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emand for blueberries has increased in recent years due to their perceived health benefits. Consequently, blueberry cultivation has expanded well beyond their native and original agricultural range, including several regions where bumble bees are not present. In South Africa, like many areas in the world, honey bees are the only commercially available pollinators for blueberries because many countries ban the importation of bumble bees. Vegetables & Fruit talked to Keanu Martin about his recent study on why honey bees are important pollinators of South African blueberries despite their inability to sonicate, and Keanu’s ongoing work in the field. He is currently finishing his PhD at Stellenbosch University where he started his research on blueberries. This study aimed to determine the benefits of honey bee pollination on blueberry fruit yield for the variety Ventura by comparing yields of honey bee-pollinated flowers to flowers where pollinators were excluded. The results showed that honey bees significantly increased berry mass by 72% and diameter by 31%. It was concluded that Ventura in South Africa can be pollinated by honey bees, and that honey bee pollination can be an effective substitute for bumble bees in areas where bumble bees are unavailable, such as South Africa. Additionally, this study revealed that the pollination environment has a strong effect on the quality of fruit produced by the southern highbush blueberry variety Ventura. Moreover, all measures of fruit yield, were improved by the presence of honey bees and more so by hand pollination. In particular, yields are greatly increased (over 130%) by the addition of honey bees to areas where there are no pollinators. This
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shows that despite their inability to buzz-pollinate, honey bees do extract blueberry pollen from anthers and transfer it to stigmas. This was demonstrated by researchers in Oregon, USA who showed that honey bees in blueberry fields carry on average 1133 blueberry tetrads on their body, excluding their corbiculae. Honey bees were the only pollinators at the site and therefore the effects shown are a direct result of access to honey bees, rather than unaccounted wild pollinators. Thus, in areas lacking native blueberry pollinators, the addition of honey bees may significantly increase blueberry yields, translating into substantial financial gains. This provides valuable information for the pollination of commercial blueberries, particularly with respect to the underutilised role played by honey bees, and suggests some important directions for research on blueberry pollination. The research showed that Ventura can produce fruit without pollinators. However, these fruits are of lower quality than the fruits of flowers exposed to honey bee pollinators. Selfpollination is not unique to Ventura, as other highbush blueberry varieties can also produce fruit in the absence of pollinators. However, these fruits also have a noticeably poorer yield compared to fruits produced by flowers with access to pollinators as found in other studies on highbush blueberries in North America. “For the last year of my undergrad I was looking for a place where I could apply science, to actually add some value to a field, because I'm not interested in just doing science for the sake of science, I want my work to have real life applications in the world around me. I started looking at, blueberries, because I identified a gap in the research, especially for
VEGETABLES & FRUIT | JULY • AUGUST 2021
