(3) Reduction of geitonogamy: Flower abscission for departure of pollinators
ERIKO ITO AND KIHACHIRO KIKUZAWA
Ecological Research (2003) 18,177-183

A flower falling with

a visiting bumblebee

According to Wikipedia, “Abscission” is a process by which a plant intentionally drops one or more of its parts, such as a leaf, fruit, flower or seed. So, Flower abscission means the drop of flowers intentionally by the plants.

Geitonogamy is the pollination of a flower with the pollen from another flower on the same flowering plant (Wikipedia). More geitonogamy is problematic for the flowers. It can reduce female fitness in self-incompatible plants and have the negative effects on male fitness reducing pollen export to other plants. In this way, plants especially large trees suffer more geitonogamy because of their size.

In this research, there are found that pollinators sequentially visited inflorescences within a tree and when they met with flower abortion by abscission, they were apt to move long distances and leave the tree. This observation prompts to tell that plants may utilize flower abscission as a method for regulating the movements of pollinators by disturbing them in order to prevent geitonogamy. They observed it in Tilia japonica Simonkai (Tiliaceae), a tall tree species growing up to 30 m in height.

According to them, this type of disturbance mechanism may exist in a widespread pattern in nature, but further study is required. Though, flower abscission reduces geitonogamy but it is very early to tell that it enhances a plant’s fitness.

(2) The importance of experience in the interpretation of conspecific chemical signals
Nehal Saleh・Lars Chittka
Behav Ecol Sociobiol (2006) 61:215-220

Foraging bumblebees use scent mark when they revisits the flowers. There are two types of scent mark: repellant mark and attractant mark. In the field observations, bees avoid the flowers using scent mark which is called repellant scent mark. On the other hand, some of the laboratory experiments reported about the attractant scent mark, by which bumblebees attract to the flowers.

The authors worked on the following questions: Do bees mark with different scents? or same scent just are interpreted differently depending on previous experience?

They found that the bee’s experience with level of reward determines how the scent mark is interpreted: the same scent can act as both an attractant and a repellant.

Probing, landing and hovering behavior are very known and common observed behaviors. Crawling-in of bumblebee seems to me a new behavior observed in this research. When the bee entered halfway into the flower, crawls back out and flew off the flower was called Crawling Behavior.

The evidence so far indicates using of scent mark is very flexible. Distinguishing the individual scents of bumblebees may provide a better understanding of the degree of flexibility of scents.

(1) Repellant foraging scent recognition across bee families
Nadine GAWALETA, Yvonne ZIMMERMANN, Thomas ELTZ
Apidologie 36 (2005) 325-330, 2005

Photo is taken from http://www.wildlife-gardening.org.uk/

Background:
It’s already established that social Honeybees, Bumblebees use scent mark to avoid the recently probed flowers, in which resources are already depleted. This indicates their efficient foraging ability. 　What about the solitary bees?

Problems:
1) What is the effect to Bumblebees if flowers previously visited by Anthidium manicatum? Or 　vice-versa.
2) Do Bumblebees discriminate different previous visitors?

Findings:
1) Anthidium manicatum also used repellant scent mark to reject previously visited flowers. So, the use of repellant scent mark is not confined to social Apidae. It also indicates that repellant scent marks are not a way of social communication in the Apidae.
2) Bumblebee can (and does) discriminate scent marks of different species.

Further Questions:
1) Are scent marking deposited actively? Or 　unavoidable footprints?

Please read the original article to know details.

Bumblebees

Bumblebees are large, fuzzy, and attractive bees. It’s easy to recognize by their size and color. Their cuticle is black and the most frequent color of patches is black and yellow but some species patches color may be white, orange, or rufous red. They visit wide variety of flowers for nectar and pollen. Most of the cases, they transfer pollen successfully flowers to flowers.
Bumble bees are social insects. They form colonies with 20 to several hundred individuals. Tasks are divided among the adults.

Darwin had fondness for bumblebees, which were called humblebees. He spent a lot of times studying their habits.

Among the insects, bumblebees are the most familiar pollinators and widely recognized as being beneficial through their role as a pollinator.

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