Pollination efficiency in deciduous fruit

A new Hortgro study starts buzzing in Western Cape pome- and stone-fruit orchards. By Nanike Esterhuizen.

The South African fruit industry faces a challenge: a heavy reliance on honeybees for pollination. With much of the R17 billion deciduous-fruit industry dependent on these invaluable insects, it’s crucial to understand what affects pollination efficiency and how we can support honeybees in our orchards.

Hortgro-funded PhD candidate Ansuli Theron has begun investigating the dynamics of honeybee pollination by assessing the attractiveness of different pome- and stone-fruit cultivars to honeybees and studying the relationship between bee visitation, cover crops, and fruit yields in orchards.

She will apply a combination of research methodologies, including literature review, stakeholder engagement, laboratory- and field-based data collection, and collaborative partnerships with local beekeepers and fruit growers.

Data will be collected from 2024 to 2026 in selected pome- and stone-fruit orchards in and around Tulbagh and Ceres. The results will help farmers and beekeepers better ensure fruitful harvests in the future.

Preparing for an uncertain future

We know that the demand for pollination services in South African fruit crops is increasing as the agricultural sector expands to supply growing local and international markets. Meanwhile, honeybees and the bee industry are challenged by limited bee forage and more frequent droughts, fires, hive vandalism, and disease.

This combination of factors could threaten the availability of managed hives to pollinate Western Cape pome- and stone-fruit orchards.

In her mission to understand and predict the future pollination needs of the deciduous-fruit industry, Theron will review the pollination literature and collect data on the current and future trends in Western Cape crop production.

She will also discuss the major challenges facing the beekeeping industry with the Western Cape Bee Industry Association and other stakeholders.

The results will illuminate the current state of pollination in the province and help deciduous-fruit producers prepare for the future.

Assessing cultivar quality for bees

In the field-based part of the study, Theron will investigate how the quality of pollen and nectar influences honeybee visits and pollination success. Different cultivars may provide varying pollen and nectar rewards for bees, influencing blossom attractiveness and visitation rates.

Pollen and nectar will be collected from selected pome- and stone-fruit cultivars for laboratory assessment of sugar concentration and composition of nectar and protein content of pollen. By analysing the sugar and protein in nectar and pollen, the less rewarding cultivars can be identified, and ways explored to improve their pollination.

With this quality assessment of selected cultivars of stone and pome fruit in mind, Theron will also measure honeybee visitation rates during pollination in different orchards and quantify the resulting fruit set.

Cover crops and pollination efficiency

In theory, orchard cover crops such as clover offer food to bees that can provide extra nectar and pollen to fuel the hive during pollination. Cover crops also improve soil structure, creating a more favourable environment for fruit trees.

The new Hortgro project will investigate if and how orchard cover crops can enhance pollination, building on Theron’s 2020–2022 Hortgro-funded MSc study that found that orchards with cover crops have higher bee visitation rates than those without.

Theron’s previous work on honeybee visitations in apple orchards with and without cover crops deepened our understanding of honeybee behaviour during pollination. Preliminary results from the current Hortgro project are similarly positive, showing more honeybee visitations in orchards with cover crops.

Orchards with higher visitation rates tend to have better fruit development and yields compared with those with lower visitation rates—something that will be investigated in the next phase of the study. Theron plans to measure yields in pome and stone-fruit orchards with and without cover crops to determine whether cover crops improve pollination.

Why do this research?

After this project is completed, the insights and findings of the study will be translated into practical strategies to help beekeepers and fruit farmers grow fruit in ways that benefit their crops, honeybees, and the environment.

A better understanding of bee behaviour, pollen and nectar quality, and the benefits of cover crops will help farmers achieve better pollination and yields.

These research findings could also inform the tailoring of management strategies to individual cultivars and orchards in the Western Cape.

About the author

Dr Nanike Esterhuizen is a beekeeper and entomology technician with Hortgro seconded to the Department of Conservation Ecology and Entomology at Stellenbosch University.