Q & A
The Natural History Museum’s Gavin Broad answers some burning questions.
Q Why are bees and other pollinators so important? A It’s estimated that the value of pollination for human food is in excess of £110 billion per year, so the collapse in numbers of bees has provoked alarm. The focus is usually on the honeybee, with the spread of the Varroa mite, pesticides and colony collapse disorder, however this is just one pollinator among many. Occasionally bumblebees, solitary bees and butterflies get a look in, but other pollinators, such as flies, beetles and moths, are often overlooked. Q Why are bees and other pollinators in decline? A There is good evidence that neonicotinoids (pesticides) have adverse effects on pollinators. It’s also pretty destructive to mow large amounts of flower-rich habitat when insects are just getting going, and before those flowers have set seed. We should all support ‘No Mow May’!
Some pollinators are in decline, especially specialists, bees and other insects that rely on particular habitats. However, it’s also the case that some generalists are doing well – bumblebees offer some nice examples. Some specialists such as Bombus cullumanus and B.
subterraneus, which require flowerrich meadows and were on the edges of their ranges in Britain, have gone extinct. Others can thrive in more altered landscapes such as Bombus
terrestris, and in the case of Bombus
hypnorum, have arrived recently and rapidly spread. Q How can people help pollinators at home? A I would suggest that gardens will benefit from a good variety of native flowering plants. Pollinators will often love various non-native flowers, which supply plenty of nectar and pollen, but these species offer little to the other insects that would be eating foliage and seeds. Let your lawn grow a bit. I know people who are very happy that their lawns have transitioned from a bowling green to a space where grasses are in the minority. Q Are non-pollinating insects important, too? A Yes, it’s not just about the pollinators. All insects play important roles in our terrestrial and freshwater ecosystems, as herbivores, predators, decomposers and food for other organisms. If populations of large numbers of insect species are declining, what does that say about our stewardship of the landscape?
Q What will help pollinators outside people’s gardens? A It would be great to encourage wildflowers by reducing mowing and just generally trying to protect species-rich open habitats, rather than grazing it all. Brownfield sites are also really productive for insects, often more so than greenbelt, which can be dominated by agriculture.
Q Do all bee species have a sting? A All bees can sting… except the stingless bees! The stingless bees are a distinct tribe of mostly tropical bees, the Meliponini. They can still deter predators by biting and have some nasty compounds in their saliva that can cause irritation.
Also, male bees cannot sting. The sting is actually a modified ovipositor – egg-laying appendage – so is by definition only present in females.
Q Do bees die after using their sting? A Honeybees famously die after stinging, but this is a special adaptation to their massive colony sizes – an individual worker is essentially dispensable when weighed against the huge resource of larvae and honey that needs to be protected.
When the honeybee sting rips out of its body, muscles continue to contract and pump venom into the intruder, and a chemical is released that attracts other workers to the defence. Other bees that can sting, such as bumblebees, do not die but live to sting another day.