Over the past two years of Plants for Bugs recording, we’ve been sampling all sorts of invertebrates (34, 000 and counting) on our plots – from bees and beetles to spiders and springtails. When the project ends and the results are analysed, we’ll be able to say whether the ‘bugs’ recorded have shown a consistent preference for native or non-native plant assemblages, or whether in fact they’re not too bothered either way…
In order to explain the reasons for any observed preference, we’ve also been recording lots of variables on the plots including numbers of flowers, seed set, vegetation density and canopy cover. But, with a project this big, there’s always more we want to record.
This year, we’re adding another variable to our list – nectar. It’s one that makes good sense to monitor as it’s likely to strongly influence the choices made by flying insect visitors.
Pollinating insects visiting (from left to right) saw-leaved speedwell (Veronica austriaca), maiden pink (Dianthus deltoides), ox-eye daisy (Leucanthemum vulgare), Caucasian scabious (Scabiosa caucasica) and Purple top (Verbena bonariensis) on Plants for Bugs
Decision made, now comes the tricky task of working out how to sample. Nylon tulle – the material most commonly used in wedding veil, is perhaps less well known for its use when bagging flowers to exclude insect visits. When sown together to form pretty, neat bags (or I suspect, rather ugly bags if your needlework is as bad as mine) to enclose selected flowers, the mesh is fine enough to exclude pollinator entry, but wide enough to allow air flow.
Bagged flowers are left for a few hours before sampling by inserting thin, glass tubes (microcapillaries) into floral nectaries; nectar is drawn up through the tubes by capillary action.
We’re collaborating with researchers at Newcastle University on this so collected nectar will be packed in dry ice and sent by courier to be analysed for its constituent sugars and amino acids.
All that’s left is for me to practice the technique on flowers in the garden before the planned sampling start date in April. It means that I’ll be denying a hungry bumblebee or two from some nectar but there’s plenty more to go around. Besides, this work will help entire bumblebee communities as results will inform more gardeners on what to plant to provide the best resource for wildlife!