HAIRY BEE TONGUES AND SHRINKING WASPS

Two stories in the biological science press caught my eye this week. The first is the discovery about how bumblebees sip nectar. Entomologists had observed that these insects are able to take thick, sticky nectar just as easily as the thin, runny sort and wondered how. The answer is that the bees have hairy tongues. Pascal Damman at the University of Mons in Belgium used 3D printing to make bee tongue models of the buff-tailed bumblebee with “hairs” at differing spacing and found the configuration that pulled up nectar of various viscosities by capillary action, just like the bees’ tongues do^[1].

^[1] Journal reference: Soft Matter, DOI: 10.1039/c9sm00982e

Buff-tailed bumblebee Bombus terrestris (Linnaeus, 1758) taking nectar from kidney vetch Anthyllis vulneraria. (Photo by Senior Betts Ecologist Kevin McGee ©.)

The second story^[2] is about shrinking wasps. We have known for a while that climate change seems to be driving a trend towards smaller body mass in some birds (e.g. sparrows) and mammals (e.g. antelope) but now it seems wasps may be affected, too. It is not clear why this is happening, but it is likely to be to do with heat stress, the relationship between body size and retaining heat, or maybe food availability.

Work at the University of Castilla-La Mancha in Spain looked at entomological specimens of tree wasps, a species of temperate regions including Britain, collected over many decades in the Iberian Peninsula. The scientists measured the body size, heads and wings of over 200 tree wasp specimens dating back to 1904.

^[2] Ecological Entomology, DOI: 10.1111/een.12781

The results were fascinating because the wasps had become smaller over the time period and the size reduction correlated with warmer climate temperatures. Correlation is not causation, of course, but in these insects one theory is that a warmer environment accelerates early larval development which in turn leads to smaller imagines (adults); other factors are likely to be influential, though. More work is needed, and it is interesting that the wasps’ wings have been shrinking faster than their bodies.

The typical paper nest of the tree wasp (Dolichovespula sylvestris Scopoli, 1763). They are only an few centimetres wide. Photo by the author.

Betts Ecology promote bees and wasps on our sites as they are highly beneficial insects. Sometimes, though, we do have to remove wasps’ nests from children’s play areas!

 © Betts Ecology