Investigating the value of gardens for providing floral resources to pollinating insects

Abstract

Introduction:

Animal pollination is essential for the production of 75% of the world’s crops, with insects playing the largest role in this service. Bees are viewed as the most significant group of pollinators, particularly the honey bee and some species of bumble bee, whose foraging habits have been studied well. As important as these two groups are for crop pollination, there is growing attention towards the role that lesser known species such as solitary bees and hoverflies contribute to this key ecosystem service. There has been a considerable decline of pollinators in recent years, owing to pressures such as habitat fragmentation, climate change, pests and disease. As floral resources are a limiting factor of pollinator abundance, gardens could play a key role in alleviating pollinator declines by providing a wealth of native and non-native resources and increasing floristic diversity. There are extensive lists available which name ‘pollinator-friendly’ plants that can be planted in gardens to aid biodiversity, however these lists can be subjective as they are usually inconsistent and a limited number are based on clear scientific evidence.

Aims: This study aims to identify the plants that wild pollinators use and determine how these can be provided in gardens and urban amenity areas. These data will be compared to a complementary project looking at the foraging habits of managed honey bees in order to ascertain the way in which different pollinators utilise the resources available to them in the landscape. The results of this project can be delivered to gardeners, land owners and policy makers to aid in pollinator conservation management.

Methods: DNA metabarcoding can be used to identify pollen carried by pollinators. Pollen will be sampled monthly from a range of wild pollinators from sites within and surrounding the National Botanic Garden of Wales. DNA will be extracted and the rbcL and ITS2 markers amplified to be sequenced on the Illumina MiSeq platform. These sequences will be compared to the Barcode UK reference library in order to identify the plants the pollen originated from. The area surrounding the study sites will be surveyed during the same period as pollinators are sampled, to create a record of what floral resources are available at each time period, and how much of the floral availability is actually utilised by the pollinators.