Last month I wrote a personal account of the National Pollinator Strategy Seminar held at Westminster. This week the Parliamentary Office for Science and Technology released their official summary of the event plus PDFs of the slides of some of the participants. They can be downloaded from this website. It was an interesting seminar and it’s well worth taking time to study these documents; they are very accessible for the non-specialist.
One thing that’s unclear to me from this account is with regard to the statement that: “there are approximately 1,500 insect species that pollinate food crops and wild plants, including bees, hoverflies, wasps, flies, butterflies, beetles and moths”. The National Pollinator Strategy also cites that figure, though says “at least 1,500” species.
Where does the 1,500 figure come from? Does anyone know the original citation? I genuinely can’t recall if I’ve ever seen it published.
A quick back of the envelope, conservative calculation suggests to me that 1,500 species is too low:
| Aculeates (bees plus wasps minus ants) = | 500 |
| Butterflies = | 59 |
| Macro-moths (assumed 50% flower visitors) = | 400 |
| Hoverflies = | 250 |
| Other flies (assumed 10% flower visitors) = | 700 |
| Beetles (assumed 5% flower visitors) = | 200 |
| Total species = | 2109 |
Links are included to the sources of the original diversity figures. I’ve rounded some of the figures down and the % flowers visitors figures for moths, flies and beetles is pure guestimate based on my field experience. But they are not likely to be way out, and if anything could be an under-estimate for flies and beetles; moths could be too high, though most species do feed as adults. Aculeate Hymenoptera (bees and wasps) could also be an over-estimate, but then that figure doesn’t include the non-aculeate “wasps” that frequently visit flowers, for example many ichneumonids and sawflies.
Does it matter? I think so: as scientists it’s important that we provide the most accurate data that we can to governments and other bodies that may use it for policy, strategy and advocacy.
As always I’d be pleased to receive your comments.
Prof. Jeff Ollerton - ecological scientist and author 
I agree scientists always need to strive for accuracy and need to explain uncertainties.
By the way where did your % assumptions come from ; )
Thanks Simon. Yes, fair point, I’ve made some assumptions in those %s, but as I said, in my opinion (based on field experience) they are low, conservative assumptions. There’s a whole set of assumptions I didn’t explore, such as whether or not very small bees are ever good pollinators, or if they just act as pollen and nectar thieves.
Just shows how little we really know 🙂