Assessing honeybees’ use of Phacelia tanacetifolia, a key component of agri-environment schemes, using molecular and field techniques

Abstract

About 70% of crops worldwide benefit directly or indirectly from animal pollination, with insects contributing the most to pollination. Of these, honeybees (Apis mellifera) are used the most by farmers for pollination services because of their abundance, generalist floral preferences, and ease of management. Increased dependence on honeybees coupled with their recent population decline has caused the European Commission to enact programs aimed at improving pollinator fitness and efficacy, called Agri-Environment Schemes (AES). While these AESs include specific guidelines for farmers and landowners to follow, scientific assessment of these AESs is still lacking. This project seeks to address this issue by assessing how honeybees use the pollen of Phacelia tanacetifolia, a wildflower commonly used in AESs, in an agricultural landscape. In order to identify accurately and efficiently the plant species of pollen that honeybees collect, this project researched existing pollen identification methods and examined Next Generation Sequencing (NGS) of pollen DNA as an alternative method. While many samples were able to be sequenced and identified to species level using NGS, it was found to be unsuitable for small-scale pollen identification projects due to its expense. Based on the pollen sequencing results and observations in the field, this study found that honeybees did not use P. tanacetifolia much for pollen, although they did forage on P. tanacetifolia for nectar. In the wider context, the overall results of this study indicate that honeybees may not prefer the flowers provided in AESs for pollen depending on the other available floral resources in the surrounding area. Since AES measures are aimed at improving pollinator health, scientists and policy makers should ensure that the floral resources used in AESs are preferred by the target pollinator group.