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Posts Tagged ‘nectar’

The Biology of Flowers, Eigil Holm, illustrated by Thomas Bredsdorff and Peter Nielsen (Penguin Nature Guides 1979)

An excellent short introduction to one of the most fascinating areas of biology. Flowers are results of millions of years of interaction between plants and animals. The first animals were insects, the next were birds, and the last so far, at least in nature, were bats. Flight is the important thing, you see, because it allows pollinators to travel far, fast and accurately between individual flowers. To take advantage of wings, plants have evolved to advertise with color, shape and scent, but those advertisements aren’t necessarily honest. Some animals are paid for their services with nectar and pollen, or even with seeds, but others are tricked into cooperating or even turned into drug-addicts.

Helleborines of the genus Epipactis, an orchid named after a plant supposed in ancient times to cure madness, actually induce a kind of madness in the wasps that pollinate them: a wasp sometimes becomes so drunk on Helleborine nectar that “it cannot fly, but walks from flower to flower, covered in pollen clubs” (the helleborine glues a little stick of pollen to the wasp’s head as it drinks the nectar). The wasps can even blunder into spiders’ webs while under the influence or end up too weak to move, caught on the sticky helleborine flower. Apart from bee-orchids, flowers pollinated by bees generally play fair. But bees don’t always play fair back: some flowers are designed for only the heaviest bumblebees to enter, so the lighter “buff-tailed bumble-bee (Bombus terrestris) sometimes steals the nectar by biting holes in the corolla tube” (the base of the flower where nectar is stored).

Talk of “playing fair” is anthropomorphism, of course: selfish genes take whatever advantage they can and if a plant has evolved to feed an animal, it’s because the animal performs some service for it in return. Plants that don’t use animals to reproduce, like the grasses, can seem less interesting at first glance, but if you wait patiently by a field of rye (Secale cereale) in summer, you might change your mind. The dull-looking rye-flowers will be waiting patiently too: for a “sudden lowering of light intensity” caused by a cloud passing in front of the sun, which will trigger the simultaneous opening of thousands of stigmas and a huge cloud of pollen. There’s a lot more to even the dullest-looking flower — and plant — than immediately meets the eye, and this book will give you many mind-expanding examples, beside enriching your understanding of those aspects of flowers that do immediately meet the eye (and nose): their shapes, colors and scents.

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A Sting in the Tale by Dave GoulsonA Sting in the Tale, Dave Goulson (Jonathan Cape 2013)

I was looking forward to this book a lot after reading A Buzz in the Meadow (2014), which is the follow-up. I was disappointed. It’s a good book, but it suffered by comparison, seeming scrappier and less well-written than Buzz. And perhaps I was comparing it with Gerald Durrell’s books too, because Goulson starts by describing his childhood as a budding naturalist. He kept birds, amphibians and reptiles, collected insects and birds’-eggs, and dabbled in taxidermy. Like Durrell, he had a lot of failures and made a lot of mistakes, but that was part of learning his future profession.

By the time he was grown-up and a proper biologist, he’d discovered his main interest: bumblebees, which are the chief subject of this book. If you’re interested in them too, A Sting in the Tale will be a good introduction to their fascinating world. They illuminate many areas of biology, from genetics to parasitism, and they’re important to human beings not just agriculturally but aesthetically too. The sound and sight of bumblebees are a wonderful part of summer. It would be a poorer and less interesting world without them, and it’s sad that some species are declining or have disappeared in the British Isles.

Goulson is fighting to re-buzz Britain. He describes how he set up the Bumblebee Conservation Trust and how he’s trying to re-introduce the short-haired bumblebee, Bombus subterraneus, to Dungeness Nature Reserve in Kent. There’s still a thriving natural population in Sweden and a thriving introduced one in New Zealand, which was founded when British bees were taken there in the nineteenth century to pollinate clover. So should the re-introduction to Britain be from Sweden or New Zealand? Goulson thought that there would be “a beautiful symmetry to the idea of bringing back these bees to the UK from the other side of the world after a 126-year absence” (ch. 17, “Return of the Queen”, pg. 236). But the New Zealand bees are highly inbred and seem to descend from just two introduced queens (pg. 234).

So Swedish bumblebees were used in the end. The re-introduction is still under way and some of the questions it raises haven’t been answered. Why are short-haired bumblebees still thriving in Sweden when they’ve declined elsewhere in Europe? And why hasn’t that genetic bottleneck harmed them in New Zealand? Goulson suggests possible reasons, but bumblebees will be baffling biologists for a long time to come. They’re hard to track on the wing and to find when they’re inside their nests, which is why chapter eight is about “bumblebee sniffer dogs”. It turned out that the dog-handler was better at finding nests than the dogs were (pp. 105-6). Experiments often go awry and hypotheses are often confounded. Like A Buzz in the Meadow, this book gives you a good idea of what it’s like to be a working scientist: it’s always fascinating, but often frustrating too.

Both books also lament the depredations of modern agriculture. And of modern horticulture: “bedding-plants have been intensively selected for size and colour, and in so doing they have lost their nectar, or become grossly misshapen or oversized so that it is impossible for bees to get to the rewards” (ch. 16, “A Charity Just for Bumblebees”, pg. 222). This means that “old-fashioned cottage garden perennials” are best: a “wildlife-friendly garden does not have to be a chaotic mass of nettles and brambles”. In the previous chapter, “Chez les Bourdons” (“At Home with the Bumblebees”), Goulson describes his attempt to establish a wildlife-friendly farm in France. That’s the tale he picks up in A Buzz in the Meadow, which uses the farm to discuss a wider variety of animals and plants than this book does.

Perhaps if I’d read the two books in the order he wrote them, I’d have enjoyed A Sting in the Tale more. As it is, the chapter I enjoyed most was “Chez les Bourdons”, which also supplied the most memorable – and gruesome – image in the book. Goulson says that kestrels catch and eat stag-beetles on warm summer evenings at his farm. But they discard the beetles’ heads, which “remain alive for a day or two, their antennae twitching and their great jaws slowly opening and closing” (pg. 203). Nature can be cruel and ugly as well as beautiful. But perhaps insects don’t suffer in any genuine sense. That’s one of the questions that biology is still to answer. In the meantime, Dave Goulson is doing a good job of explaining his science to the general reader.

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