I used to take bees for granted, that is, till I started growing chilly peppers and tomatoes. In my mother’s suburban garden where gleaming, midnight-blue carpenter bees like to fly, eggplants, tomatoes, okra flower, then fruit, seasons turn, and all is as it should be.
But up here on the fifth floor in the middle of a busy city block, the nightshades I grew early on in the year did something strange. They flowered, but nothing happened after that. The flowers simply withered and fell from the parent plants stems and all. The issue was pollination, or the lack thereof. There were bees around, all kinds of bees, the little striped hive-making honey bees: apis florea (the dwarf honey bee pictured above), apis mellifera (the European honey bee) and the native apis cerana (the asiatic honey bee); the big ones: apis dorsata; and some solitary bees: nomia bees and resin bees. But soon I realised, they were just not the right kind, my little solanacea were after _ wild, native bees of the bumble, carpenter and halictid variety were absent from my terrace garden. Apparently, even a dulcet-toned breeze that shakes the self-fertile tomato flower could have done the job, but even these seemed to have gone wanting at the right time.
As I started reading up on this perplexing problem, it occurred to me that if I could not find the appropriate brightly-coloured almost-neon American halictid to do the job all the way here in India, I would have to depend upon sonicating or “buzz pollinating” local bees. Sensitive bumble bees stayed away from my garden as our apartment building stands in the middle of a densely-populated, traffic-filled area also crowded with mobile-phone towers. The next best buzz-pollinator was the blue-banded bee, which fortunately were plentiful here.
I had found out that tomato and pepper flowers need to be sonically buzzed at opera style by bee-wing muscles and induced into spurting out their pollen, which is what certain bees like to collect in little white or yellow bundles on their legs. A portion of this released pollen sticks to the sticky stigmas of the same flowers causing self-fertilisation, and cross fertilisation takes place when bees rub their hairy pollen-covered bellies on the style tips. I found the best explanation here at the Old Drone blog.
Blue-banded bees with their dazzling turquoise colours do come to my garden from time to time. They, however, did not seem to be attracted to the yellow flowers of my tomato plant. They seemed instead to prefer the violet colours of a singular Buddleja specimen. In fact, the yellow tomato flowers and white chilly pepper flowers did not attract any of the bee visitors to my garden. And I hadn’t had a single tomato or pepper fruit yet, although the plants were all flowering profusely.
At our local botanical garden, I had been witness to flowers of a nightshade brinjal being visited by other “apisian” guests. Sadly, being no expert, it was difficult to make an identification of the kind of bee. To me, it looked like a sweat bee, a halictid. A type of bee I have never seen in my fifth-floor terrace garden.
After some internet searches, I decided to resort to the old electric toothbrush technique. My first attempts at hand pollination were on a Thai chilly pepper growing on the kitchen window sill. I discarded the brush end of the toothbrush and touched its vibrating metal head to the flower’s anther cone, and voila, and pollen spurted out. I collected this flying pollen and used a cue tip to transfer pollen gently onto the stigma of the pepper flower.
When the flowers were successfully pollinated and I got them to fruit, I began my toothbrush experiments on the tomato flowers.
On the whole, it was a satisfactory experiment. Since the pollen-receptive stigmas of my tomato flowers lay just inside their anther cones (see picture above), my attempts at transferring pollen with a cue tip did not work. In this case, merely sonicating and gravity did the job of pollen transference. My little tomato plant produced a whole bunch of fruit before it finally gave into blight.
- Citizen Science: How You Can Help Bees (sierraclub.typepad.com)
- Do the Whims of Bees Impact the Color of Flowers? (proflowers.com)
- The Abundance and Pollen Foraging Behaviour of Bumble Bees in Relation to Population Size of Whortleberry (Vaccinium uliginosum) (plosone.org)
- “Self Pollinating” and Tomato Growing Mythology
- Bumblebees do best where there is less pavement and more floral diversity (esciencenews.com)