The importance and value of insect pollination to apples: A regional case study of key cultivars

Abstract

Increasingly, the importance of both varietal and regional variation in crop pollination requirements is becoming apparent in terms of informing the management of crop pollination services. Apples are an economically important crop pollinated by both wild and managed insects, but evidence suggests that insect groups can differ in their contributions to apple pollination between both regions and varieties. To address the increasing need for a more context-specific understanding of crop pollination, we assessed the pollinator importance of different insect guilds and pollinator dependence of two apple cultivars widely grown in Ireland: Jonagored and Dabinett. We found that insect pollination differentially increased the yield and economic profit of both cultivars, contributing to 93% of Jonagored market value and 46% of Dabinett market value, equating to over €800,000 per year to their combined production in Ireland. We also found that, while honeybees, bumblebees, solitary bees, and hoverflies all contribute to the pollination of apples, these contributions differ between guilds and apple cultivars. Our results suggest that honeybees and bumblebees are the most important pollinators of Jonagored apples, while honeybees contribute the most to Dabinett pollination. Honeybee visitation rates vary considerably between cultivars, suggesting the need to insure pollination services through land management strategies that prioritize maintaining and increasing wild insect diversity. Increasing hoverfly and solitary bee abundance may be good targets for future pollinator management since we found that hoverflies exhibit high abundances and floral visitation rates and that solitary bees transport large amounts of apple pollen, despite their low abundance. Our work shows varietal differences in the pollination requirements of regionally-specific, within-crop cultivars, thus confirming the need for a more comprehensive understanding of crop pollination requirements at varietal and regional levels to ensure appropriate pollinator conservation and pollination management.