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Alula Images From Palomar College Hawaiian Garden 2
Flower Bee Collecting Pollen From Alula Flower
© Updated W.P. Armstrong 17 November 2019
       Hawkmoth Pollination       Back To Alula Page 1  

  Polynesian Garden At Palomar College Arboretum  
On 16 Nov 2019 at 12:00 noon I spotted a small, black, solitary flower bee on an alula flower in the Palomar College Polynesian Garden. I originally thought it was in the family Megachilidae, but according to Karl Magnacca at University of Hawaii, it belongs to the genus Lasioglossum in the family Halictidae. Bees in this family are important pollinators in San Diego County, particularly the Anza-Borrego Desert region. This bee was definitely interested in the alula flower and was in the apex of floral tube collecting pollen grains from the anther column and from corolla throat. I collected the bee and flower and placed them in a closed vase with water for observations. I watched the bee move about on the flower and it appeared mostly interested in the pollen-bearing anther column; however, after several days it landed several times on the stigma. My observations are substantiated in the following images.

The act of collecting pollen does not necessarily result in pollination. In the case of Brodiaea santarosae on the Santa Rosa Plateau of Riverside County that I named with Tom Chester, visits by flower bees undoubtedly pollinated the flowers because of the close proximity of floral organs (anthers & receptive stigma). In alula flowers the receptive stigma extends out beyond the anther column and corolla throat. I think it is possible for flower bees to inadvertently transfer pollen to the stigma as they move about on the corolla, but in my observations they seemed primarily interested in the anther column within corolla tube and masses of pollen on the corolla throat. Megachilid bees carry the pollen back to their nest in a pollen carrying structure (scopa) on the underside of their abdomen. Other families of bees carry pollen on their hind legs. In my humble opinion (humble hypothesis), a large "furry" hawkmoth visiting this flower is more likely to transfer pollen to the exerted stigma.

  Flower Bee On Brodiaea santarosae From Santa Rosa Plateau  

Unlike fig wasps of the family Agaonidae, there doesn't appear to be an instinctive, purposive, mutualistic relationship between pollen-collecting by the flower bee and transfer of pollen to the receptive stigma of alula flower. In other words, if any pollen gets on the stigma it is probably unintentional; however, on 18 Nov 2019 while in captivity she moved up and down style to stigmatic surface & back to anther column several times. She even landed on the stigma! I did not observe her physically transfer pollen from her body to the stigmatic surface; however, she did move around on the stigma. Although I can't completely rule out flower bees, the pollination of alula in the Polynesian Garden at Palomar College remains an enigma. To appreciate the complexity of fig & fig wasp life cycle, including purposive pollination, see the following links:

       The Sex Life Of Figs       Sexual Suicide: Male Gender Inequity  

Images Taken In The Polynesian Garden With Sony T-10

Images Taken In Closed Vase With Nikon D-90

I have taken this picture with iPhone 6, Sony T-10, and Sony HX-60 point & shoot cameras. Although they make a fairly good image, only the superior macro lens of my old Nikon D-90 can resolve the detail of hairiness (pilosity) on this fascinating little bee.

18 Nov 2019 4:00 PM: Flower Bee Moved To Stigma & Back To Anthers

She moved up and down style to stigmatic surface & back to anther column several times. She also collected pollen on corolla throat. I am certain she had pollen grains on her hairy abdomen & possibly her legs & thorax. I replaced glass vase over her & turned off my photoflood lamp. Then suddenly she flew to stigma & moved around on the stigmatic surface. I quickly took the following image with reduced light to avoid reflections. I couldn't remove vase because she would fly away.

Close-up view of underside of flower bee from alula flower. The abundant, long, curved hairs could easily trap pollen. I observed a few pollen grains among the hairs, but unfortunately they are out of focus in this image. The bee fell into water flask containing alula flower stalk and drowned. By the time I recovered her body, it was soaked and withered. Thanks to bee expert Karl Magnacca at University of Hawaii, this bee is in the genus Lasioglossum (family Halictidae). The large family includes sweat bees, so named because they apparently are attracted to the salt in human sweat. In fact, I had several nests of a beautiful metallic green species in the bridle path in front of my home in nearby Twin Oaks Valley.

To my surprise, this was not the entrance to an ant nest. It is a ground-nesting metallic sweat bee. I collected one of these for my entomology class at CSULA almost 60 years ago. I have kept it all these years.

Did Any Alula Pollen Adhere To Flower Bee?

The flower bee (Lasioglossum) definitely picked up alula pollen on its hairy body and appendages. The above image shows alula pollen grains on compound eye and on fringe of hairs around mouth region below clypeus. There were also scattered pollen grains on its thorax and abdomen. I also observed tricolporate pollen grains on the hairy upper and lower surfaces of alula stigma. I compared them with pollen grains on anther column and they appeared to be from an alula flower, undoubtedly transferred by an insect! Note: In this image I have pushed my old Nikon D-90 (with macro lens + 3 extension rings) to the limits of its resolving power.

Tricolporate pollen from alula flower. The grains have a triangular shape with 3 furrows or grooves in the exine (outer layer of grain). Most of the grains in this image appeared viable (not empty or shrunken), but I did not test them with stains. Photographed through 100x objective on compound microscope and zoomed up to at least 200x magnification with Sony W300 digital camera. Note: Alula pollen tested with Alexander's stain by Beth Pearson of the Palomar College Life Sciences Department appeared magenta-red, indicating pollen viability.

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