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Beetles and humans

attract pollinating insects—usually sugary

nectar—and to access it, the insect must contact

stamens that deposit pollen and a stigma that

removes and uses any pollen from other flowers.

Insects move between flowers of the same species,

searching for the reward, and at the same time

distributing the plants’ genetic material. Some

insect groups become specialized pollinators of

particular flowers, guaranteeing a source of food,

and at the same time ensuring the plants

reproduce. Such insects often evolve structures

that make them better pollinators, such as the

fuzzy setae of bumble bees and flower chafer

beetles that hold more pollen. This in turn

increases populations of the plant on which they

rely, so is an example of mutualism, a relationship

between organisms where both benefit.

When we think of pollinators, we often think

of bees and butterflies, but in the early Cretaceous

when flowering plants first diversified, beetles

were likely the first pollinators, just as they were,

and still are, the primary pollinators of cycads and

some other ancient plants. In modern ecosystems,

beetles still play an important role in pollination,

especially of flowering trees, and in tropical and

arid environments. Beetle-pollinated flowers

are often large or clustered, pale-colored,

and may have a strong, sweet, sometimes

even sickly scent. Examples include

water lilies, arum lilies, magnolia, and

hawthorn blossom. The fleshy petals

of many of these, especially magnolia

and water lilies, reflect an ancient

association with beetles and protect the

flowers from the beetles’ chewing

POLLINATION

Angiosperms, flowering plants, are the dominant

plant group in land ecosystems today, in both

volume and species diversity. Most of the crops we

eat are angiosperms, and as well as feeding us and

shaping the habitats of the planet, plants produce

the oxygen we breathe. Humans, like beetles and

most other animals, rely on plants to exist.

As land plants are stationary, they cannot

search for mates like animals do, so to reproduce,

they discharge their male gametes, pollen, into the

environment, aiming for some to reach the female

flowers of another plant of the same species.

Many plants rely on wind pollination, producing

huge quantities of pollen so that a few grains of

the millions will reach the right female flowers, but

a more targeted strategy, in many of the higher

plants, is to use insects for pollination.

Insect-pollinated plants have obvious flowers,

combining both male and female organs, often

developing at different rates in each flower to

avoid self-fertilization. They provide a reward to

left | Meligethes aeneus (Nitidulidae)

A mass of tiny pollen beetles pollinate

a yellow zucchini (courgette) flower in

an English garden.