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FIGURE 1. Foraging bees identify desirable flowers by color (bees don’t see red, but do see blue, yellow, and ultraviolet), shape (flowers that are relatively shallow), and smell (flowers typically have a delicate, sweet scent). Some bee-pollinated blossoms must be visited multiple times to produce fully-formed fruits.

   
 

 

FIGURE 2. Pollination is a complex activity. In the case of cucumbers and other cucurbits, it can involve the transfer of pollen from male flowers (shown above on the left) to female flowers (shown above on the right).

   
 

 

FIGURE 3. Flowers with a deep corolla tube (a tube formed by the perianth segments) and radial symmetry are often pollinated by lepidopterans (butterflies, skippers, and moths) which have a proboscis that long enough to probe for nectar in flower tubes that are too long for bees. Pictured above is the Long-tailed Skipper (Urbanus proteus) feeding on flowers of hummingbird bush or firebush (Hamelia patens).

   
 

 

FIGURE 4. The flowers of some plants have ingenious insect traps and pungent odors (ranging from malodorous to downright nauseating) when their blossoms open. For example, the showy maroon calyx-like corolla of the Brazilian Dutchman's pipe (Aristolochia gigantea) has an "inviting" orifice leading into an inflated, bladder-like trap (shown in the side view of the flower on the right). Fly pollinators remain trapped for several days before gaining their freedom only to repeat the process upon visiting the receptive floral trap of a different flower.

   

To understand the value of pollinators, the first question we have to ask is what is pollination? Pollination is the means in which pollen is transferred from the male parts of a plant to the female parts of the same plant or another plant (same species) so they can reproduce by forming seeds.

Considering plants don’t move locations, the pollinators have to come to them. Flowers are categorized by various factors. Plants with imperfect flowers have either all male parts/male blooms or all female parts/female blooms (but not both) in the same flower. Well known examples include cucumber, pumpkin, squash, watermelon and other cucurbits. Plant with perfect flowers have both the male parts and female parts in the same flower. Well known examples include dandelion, roses, peaches, lilies, etc.

Some flowers have a general shape and attract a wide variety of pollinators. The flowers of other plants are formed to attract specific pollinators with color, nectar, scent and/or structure. This is a “mutualistic” relationship as both plant and pollinator benefit from one another.

For example, the flowers of a Brassia arcuigera orchid look like spiders and lure their pollinator, the Cryptocheilus bicolor wasp. This wasp attacks the flower mistaking it for prey and in the process the pollen attaches onto the stinger. When the wasp attacks another Brassia arcuigera, it transfers the pollen onto that flower’s stigma, completing the pollination.

Another example is the Ficus carica or fig tree and Blastophaga psenes or fig wasp. Plant species that depend upon a single pollinator species for reproduction and, alternatively, pollinators that depend upon a single type of plant for sustenance, are interdependent. If one disappears, so will the other.

Even more interesting is co-evolution. Take the yucca plant. The design of the yucca flower is such that it cannot be pollinated in an ordinary manner. The yucca moth (Tegeticula maculata) is the only animal that is the right size and shape to pollinate yucca flowers. A gravid (pregnant) female yucca moth has palps (mouthparts) that allow her to gather about a dozen pollinia, which she forms into a ball. Tucking the pollen under her “chin”, she flies to another yucca’s flower and climbs to the side of the ovary where she deposits her eggs. She then carries the pollen to the top of the ovary and deposits it in the stigma insuring cross-pollination. Once the yucca is pollinated, its flower can produce seeds.

Yucca moth caterpillars feed exclusively on yucca seeds (but no worries, there are many left over to produce new yucca plants). As the yucca plant can only be pollinated by yucca moths and yucca caterpillars only eat its seeds, both the moth and the plant depend on each other for survival. Voila, co-evolution.

The flowers of some plants have ingenious insect traps and pungent odors (ranging from malodorous to downright nauseating) when their blossoms open. For example, the showy maroon calyx-like corolla of the Brazilian Dutchman's pipe (Aristolochia gigantea) is the size of a large dinner plate, with an "inviting" orifice leading into an inflated, bladder-like trap. Dense, downward-pointing hairs in the floral tube prevent the fly pollinators from climbing out. During their incarceration, the flies receive rations of nectar. Several days later, when the anthers release their pollen, the exit-restricting "jail hairs" wilt and the flower tilts horizontally, allowing the pollen-laden flies to walk out of their temporary prison, and into another receptive floral trap of different flower.

The second question is what is a pollinator? A pollinator is an organism that assists in transferring pollen, allowing plants to fertilize for fruit and seed production. Most folks think of bees as pollinators, but there are about 1,000 species of other valuable pollinators such as ants, beetles, butterflies, flies, moths, spiders, thrips and wasps. Though people may consider these insects to be a nuisance, just remember they are a crucial part in any ecosystem, and if insects disappeared every ecosystem would suffer.

But don’t stop there—bats, hummingbirds and other small mammals do their part in the pollination process. When these creatures eat pollen, grains are caught on their fur and feathers, along with their paws and noses, and then transfer the pollen to other plants.

Lastly, who cares? Certainly, the plants do, as over 200,000 plant species worldwide depend on pollination. And excuse me, but we do too—culturally, environmentally, economically. Do you know that (on average) one-third of every food, spice or condiment we consume, or beverage we drink, and more than half of the world’s diet of fats and oils, are because of a pollinator? They are essential to human existence.

Around 80% of the world’s crop plants depend on pollination. Almonds, apples, blueberries, carrots, cherries, cocoa, coffees, grapes, melons, peaches, squashes, are just a few examples. Without pollinators, the crops that are dependent on them for production would dissipate. We would not have those crops for consumption, much less the cotton crops for the clothes we wear. And let’s not forget the livelihood of farmers who depend upon these crops.

Then there are the plants used in research for the medical industry. All these end-use products amount to roughly a combined annual $20 billion industry in the U.S. The economic impact alone is staggering.

We must also be aware of the environment. Think about the results if there were no more pollinators. Soil-holding and soil-enriching plants would no longer exist in uncultivated areas that are also nesting grounds for some of these creatures. Imagine what would happen then? We would not have gardens, much less wildflowers, without pollinators, as around 80 percent of all flowering plants are dependent on pollinators to survive.

Statistically it is impossible to state the diversity and importance of pollinators. Without them, not only does nature suffer, but we do too. We need to do more to understand and protect the pollinators so they can carry on with their business of helping us.

In today’s world, many pollinators’ existence is threatened. Crops are decreasing production because of the shortage of pollinators. We have ignored their value and indiscriminately annihilated them with habitat destruction, chemicals and other carelessness.

Urban expansion eats away at these creatures’ homes. Roads replace fields. (Mowing down milkweed imperils the monarch butterfly, which only lay its eggs on this plant.) Landscapers replace native vegetation with exotic garden plants and large expanses of lawn.

Misuse of insecticides (applications to non-target areas, excessive applications, applications under windy conditions, etc.) are also at the top of the list, killing off pollinators necessary for plant production. Herbicides decrease many “weeds” that are requisite to a pollinator’s life.

So please take the time to understand their benefits. Work to keep them healthy. What can you do for pollinators? Here are some examples:

Create a pollinator-friendly garden habitat, install “houses” for bats and native bees
  Practice safe use of pesticides and utilize a least-toxic approach to pest control
  During extended periods of dry weather conditions, provide a supply of water for our beneficial pollinators

On a final note, mammals will wander about finding a mate for reproduction, but a firmly rooted plant can’t drop by the local pub. Keep those pollinators safe.

Beneficials in the Garden & Landscape is an Earth-KindTM program coordinated through Extension Horticulture at Texas A&M University. Earth-Kind uses research-proven techniques to provide maximum gardening and landscape enjoyment while preserving and protecting our environment.

 

This web site is maintained by Master Gardener Laura Bellmore, under the direction of William M. Johnson, Ph.D., County Extension Agent-Horticulture & Master Gardener Program Coordinator.

All digital photographs are the property of  the Galveston County Master Gardener Association, Inc. (GCMGA) © 2002-2006 GCMGA - All Rights Reserved.