Northern BC (Bulkley-Nechako and Fraser-Fort George): Finding our farm pollinators

Introduction

Insects pollinate many crops. In some cases, this process is essential for food production (and hence, food security); however, in other cases, insect pollination may not be essential but can greatly increase yields. Understanding the pollination services being provided in an area requires information on a number of factors, but it starts with quantifying the number and types of pollinator species as well as their abundance.

While much research has been done in the Lower Mainland and Okanagan regions, there are research gaps further north in B.C., such as in the Bulkley-Nechako and Fraser-Fort George (BNFFG) Regional Districts. Producers, agronomists, and government scientists are interested in gaining a better understanding of the pollinator communities in these regions. Having a baseline pollinator assessment also allows us to understand how these communities change over the years, particularly with climate change.

The goals of this research were to:

• Quantify pollinator diversity in northern areas
• Quantify relative abundance of pollinators  
• Identify the pollinators closely associated with crop plants

Research Process

The project sampled 18 farm sites in the BNFFG region. Most of the sites grew crops at least somewhat dependent on insect pollination. The two methods of sampling used were pan traps and vane traps. Vane traps were used as a supplementary method to pan traps, as they provide a longer-term measure of pollinator diversity. Pan trap samples were taken from both field edges and field interiors to assess for differences in pollinator abundance and diversity and to see the influence of adjoining land use.

Three different colours of pan traps were used (yellow, blue, white) as different insects are attracted to different colours. For each round of sampling, pan traps were left for one rain-free 24-hour period while vane traps were left all season. Collections of samples were taken every two to three weeks from May to August 2021. Insects were sorted in Petri dishes and unlikely or known non-pollinator specimens were set aside. All other items were separated by unique morphological features and each unique specimen was sent for identification via DNA barcoding. The remaining specimens were identified using a combination of the barcoding results and morphological identification keys.

Results

Researchers identified 224 likely or known pollinator species. The majority of likely pollinator species collected were flies (109 species), followed by bee species (72) and moth and butterfly species (30). The most numerous species was the fly Sylvicola punctatus. Six bee species and one hoverfly species accounted for approximately 30% of all pollinator species collected.

Differences in species richness between pan traps from the edges of fields versus the field interiors were minimal. There was, however, a difference in the abundance of several pollinators between field edges and interiors. Field edges had substantially more pollinators in two fly families, three bee families, and 12 hoverfly species. Some species were exclusively found in either field edges or field interiors. Bumblebees and sweat bees were more numerous in interiors.

Seven out of 13 sites used for forage crop production or pasture were hayed. Species richness increased modestly on the sites that were not hayed, while species richness declined substantially on sites that were hayed. Interestingly, on sites that would later be hayed, pollinator species richness was higher early in the season than on similar sites that were not slated for haying.