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THE OTHER POLLINATORS  by Wayne Handlos

1.  2. 3.  4.

  1.Buzz bee pollination    2.Gerbil on Massonia      3. Oil collection bee     4. Oil producing green orchid Pterygodium

5.  6. 7.  8.

5. Dalechampia resin gland      6. Ophryps apifera flower   7. Ophrys insectifera flower  8. Goriosa superba flower 

 9. 10. 11. 12. 

9. Stapelia flower       10. Pollen wasp on Schinus       11. Spider hunting wasp on Eucomis  12. Malachite sunbird on Protea

13. 13. Bat pollinated sausage tree flower

9. Stapelia gigantea flower 10. pollen wasp on Schinus  11. spider hunting wasp on Eucomis  12. Malachite sunbird on Protea

In previous newsletters we have learned about the pollinators of Pelargonium flowers. These fit the

usual suspects’ list - bees, flies, butterflies, moths, birds and beetles. But this is just the tip of the iceberg

– there are many other specialized pollination relationships among the plants and animals that inhabit the

Earth. In addition there are two abiotic (non-living) pollination syndromes (wind and water).

It has been the prevailing belief (from studies in North America and Europe) that flowers are generalized

 in form – i.e. they attract/appeal to a variety of pollinators. Think about the lavender plants in your garden.

On any given day a variety of bees and butterflies are attracted to the same plant, generally in search of

nectar as a source of food or nectar with which to make honey. Many bees visit flowers to collect pollen,

also a food source. While visiting the flowers, pollen may be deposited somewhere on the bee’s body and

carried to another flower, thereby effecting pollination and ultimately seed production and another

generation of plants. Nectar or pollen are the reward. Bright colors and UV reflections aid in attraction and

recognition of specific flowers for the pollinators. (The UV light primarily aids insects.) Lines and spots on

the flowers aid the pollinators (especially insects) in finding the location of the reward. Floral scents may aid

in attracting pollinators or assist in communicating the type of flower with a reward to other bees in a hive.

(The “dances” that bees perform in the hive transmit information about direction, distance and amount of a

reward while the scent carried on a bee’s body indicates the smell of the food source.)

Goldblatt and Manning reckon that there are at least 17 pollination syndromes among the Iridaceae alone

in South Africa. Several of these are ones we’ve seen among the species of Pelargonium – bees, long-

proboscid flies (four types), butterflies, moths and birds (plus a few beetles and ants).

In addition they have added a “buzz bee pollination syndrome” where the plant has pendulous, bell-shaped

 flowers where bees cling upside down and vibrate to cause pollen to fall from the flower onto the bee for

 collection.

But among the many species of bees, not all of them collect nectar and pollen. Certain bees visit flowers to

collect oil which is used for food. Many South African orchids produce oil in addition to pollen.

In other cases, certain species of bees come to flowers to collect resin which they use to seal the compartments

 in their nests where the “baby” bees (larvae) develop.

Studies on New World orchids have revealed that some orchid species produce substances which appear

to drug or intoxicate bee visitors. In their altered state the bees pick up orchid pollinia which are eventually

transferred to other intoxicating flowers of the same orchid species.

Other flowers (again, especially in orchids) mimic specific female insects in look and scent. When male bees

find these potential partners, they land on the flower and try to mate with it. As the male bee attempts to mate,

the orchid deposits pollen (pollinia) on the male bee. Undeterred (and presumably unsatisfied), the male flies

off in search of another female. At a later rendezvous, a receptive flower receives the pollinia from the amorous

male bee.

In other cases a male bee is deceived into “thinking” that a bee-like flower is another bee invading his territory.

In the process of attacking the floral foe, pollinia are transferred to the bee only to be carried to another territorial

encounter and deposited on another flower which looks like an invader bee.

The flower of Gloriosa has a distinctive appearance and has been found to be pollinated by large butterflies.

In addition to the different appearances of the flowers pollinated by the two groups of moths described last

month, both types are scented in the late afternoon and evening. The flowers pollinated by noctuid moths

provide a landing platform for the moth while it feeds from a short nectar tube, while the flowers pollinated

by sphingid or hawkmoths have no landing platform as these strong fliers hover at the flower while drinking

from a long nectar tube.

We have described the long-nosed flies and the long-nosed hovering flies, flower- and bee-flies as pollinators

of Pelargonium. They are also very important pollinators of the flowers of the African Iridaceae.

In addition, some flowers mimic dead or rotting flesh in appearance and odor. This attracts muscid (house and

blue-bottle) flies who come to lay their eggs in rotting meat as a suitable food source for their larvae (maggots).

In the process of moving around to lay their eggs the flies pick up pollen (usually in pollen sacs or pollinia) which

is then transferred to another smelly flower effecting pollination. This syndrome is called sapromyophily.

March flies are small, nectar-feeding flies in the family Bibionidae and appear to feed exclusively on an endemic

species of iris in South Africa (Melasphaerula ramosa) with small, zygomorphic flowers. Pollen is picked up while

the insect feeds on nectar.

Pollen-collecting wasps, which look like our yellow-jacket wasps, are found in Africa, North and South America

(as well as California). They collect nectar and pollen to feed their larvae which are housed in mud nests. The

pepper tree in its native Brazil is pollinated by these wasps.

Spider-hunting wasps sting and collect spiders as food for their larvae. These spiders are normally buried in

subterranean nests. The adult wasps feed on flowers with bitter tasting nectar which is apparently unpalatable

to other insects. Some of the unusual, South African Ferrarias fit this syndrome.

Figs and wasps. See the website www.figweb.org for an amazing coverage of this specialized group of plants

and wasps.

Hopliine or monkey beetles have been found on a few species of Pelargonium, but in South Africa monkey-beetle-

pollinated flowers are much more common in other plant families. These flat flowers (usually composite heads

composed of many individual small flowers have central dark spots, which the beetles (with apparently poor eyesight)

view as potential mates and come to copulate with them. In the process of moving around pollen is picked up and/or

deposited, effecting pollination for the plant.

Bird pollination is unknown in Europe but sunbirds in Africa are important pollinators in certain plant families (especially

the Proteaceae and Iridaceae – think Gladiolus and Watsonia). Here the flowers are rugged/strong and tend to be

borne on sturdy stems which allow the birds to perch on them while probing the flowers with long, thin, curved beaks.

(Sunbirds are much larger than most of our hummingbirds.) Hummingbirds because of their aerodynamics can hover

and drink nectar while in flight. Therefore the flowers pollinated by hummers are frequently pendulous or borne on thin

 stems without a landing platform or perch. Bright colored flowers (especially red, yellow and orange) are found

attractive to both kinds of birds. Birds do not have a highly developed sense of smell so these flowers normally are

odorless. In the Indo-Australian region nectar eaters pollinate flowers; honey parrots in Australia with brush tipped

tongues are important pollinators. The honey creepers in Hawaii are well adapted to many local plants like Lobelia

(even though a number of bird species are now extinct because of introduced [feral] cats and mongooses).

Wind pollination is common amongst the grasses and grass-like plants as well as deciduous trees and shrubs in

temperate regions. The flowers tend to be small, green, numerous and borne outside the leaf canopy. Think oaks,

willows and pines. Pollen is moved by the wind and is generally very abundant. Think hay fever and yellow sidewalks.

Water pollination is confined to relatively few plants – particularly the submerged, flowering plants (water

weeds) – like some of the freshwater aquatic/aquarium plants (Elodea, Vallisneria, Lagarosiphon,

Hydrilla). In these plants the small male flowers are released underwater, rise to the surface and float

around. The female flowers are borne on long stalks at the surface of the water with protruding sticky

stigmas. Pollen is transferred when the two meet.

The world of pollination and pollinators is incredibly fascinating, complex and enlightening. It is central to

the diversification and evolution of flowering plants. While much is known, it is clear that a tremendous

amount of work waits to be done before we fully understand what is going on in the natural world.

Undoubtedly many species of pollinators and their plants will go extinct before we have a chance to observe

and understand them. The pressures of large human populations, cultivation, grazing and deforestation will

all take their toll and we and our natural world will be left all the poorer.

 

 

 

 

 

© 2014, Central Coast Geranium Society (CCGS )