Thursday, December 17, 2015

What do insects have to do with eating, drinking and kissing this Christmas?

We don’t often associate insects with Christmas. However, without them, we wouldn’t have many of our Christmas foods, drinks and decorations. This is because many of the plants that produce our Christmas treats rely on insects pollinating flowers earlier in the year. Without these insects, we wouldn’t have bright red holly berries to decorate our Christmas puddings, mistletoe with its characteristic white berries to kiss under, cranberries to liven up our turkey, chocolate, marzipan or many of the spices and other goodies we associate with Christmas. This is because insects are needed by most plants for cross-pollination, which results in the production of fruits and seeds. Since plants cannot move to find mates themselves, they rely on insects to bring male and female together.

Holly (Ilex aquifolium) is unusual in the plant world because male and female flowers occur on separate shrubs. As bees drink nectar from male flowers, they get pollen on their bodies and when they move to a female plant to continue to feed, they deposit that pollen on female flowers. The pollen causes the female flowers to be fertilized, and to form fruits (or berries) containing the fertilized seeds.

A bumblebee visits a Holly flower in Co. Wicklow in
April to drink nectar. (Photo J. Stout)

Similarly, mistletoe (Viscum album) also holds its male and female flowers on separate plants. Plants are partially parasitic and live on the branches of other trees but still rely on insects (not just bees, but also flies, bugs and beetles) for pollination and thus berry production. In fact, both mistletoe and holly fetch higher prices at market if they have berries on them, and so insect pollinators are of economic value at Christmas time as well.

Cranberry bushes (Vaccinium macrocarpon) produce both the male and female structures not just on the same plant, but in the same flower. However, they still need bees to transfer the pollen between flowers, because those male and female structures do not mature at the same time.  Large bees, such as bumblebees, which can shake the flowers at just the right frequency to dislodge the pollen (producing a distinctive buzzing sound) are the best pollinators. This is known as “buzz pollination” and is important in other crops too (including tomatoes and blueberries).

Chocolate-producing cocoa trees (Theobroma cacao) produce small flowers on their trunks, and although flowers don’t produce a scent to attract pollinators, they produce a small amount of nectar and are visited and pollinated by tiny flies (midges). Although flowers contain both male and female structures, they cannot fertilize themselves, and these midges are needed for the production of cocoa fruits, which contain the seeds from which we derive chocolate. These trees grow in the tropics and flowers and fruits are produced throughout the year, although it takes 5-6 months for them to mature before they are harvested.

Marzipan (almond paste) is made of ground almonds (and sugar). Almond (Prunus dulcis) trees bloom in early spring and are visited by bees – both managed honeybees and wild bees. In fact, almond trees in California (where most of the world’s almonds are produced) produce better yields when both honeybees and wild bees are present in orchards. This is because they complement each other in their foraging. If there are no bees at all visiting flowers, fruit set can plummet by up to 90%.

Honeybees are important pollinators of
almond flowers (Photos J. Stout)

Many of our Christmas spices, including cinnamon (Cinnamomum spp.), cloves (Syzygium aromaticum) and nutmeg (Myristica fragrans), essential ingredients in Christmas cakes, puddings and mulled wine, also need pollinating by insects. In the case of cinnamon and cloves, this is done by bees, but for nutmeg, it’s beetles that do the pollinating job.

So, as you enjoy Christmas this year, raise a glass to the insects that made all of this possible.

For more information on pollinators, their value and conservation, see the All Ireland Pollinator Plan

Posted: Professor Jane Stout

Originally published in the Independent supplement on the Science of Christmas 14th December, 2015


Wednesday, December 16, 2015

There are some things that you never get to hear about: The Botany Bake Off

There are some things that you never get to hear about.  The Botany Department at Trinity College is currently having a bake off competition inspired by the BBC TV series the Great British Bake Off.


One fascinating entry was this lovely chocolate cake of a pine stump.  Why?  Well it represents Botany PhD student Alwynne McGeever’s work studying fossil tree stumps and pollen grains to uncover when pine populations were rising and declining throughout Europe over the last 10,000 years.  It was presented at a recent departmental coffee break in the library and it tasted as beautiful as it looked.  Now you wish you did Plant Sciences at Trinity College Dublin!

Sunday, December 13, 2015

PhD student on plant collecting expedition in South East Asia

PhD student Dongwei Zhao, who is working with plant taxonomist Professor John Parnell, is currently on a plant collecting expedition in South East Asia.  He is working on Camellia species and is visiting various herbaria as well doing field work.  The image is from Loei in Northern Thailand and Dongwei is in blue.

Thursday, December 10, 2015

Genetic variation in Irish perennial ryegrass: New reserach

Irish Perennial Ryegrass

TCD botanists Sai Krishna Arojju, Sarah McGrath and Trevor Hodkinson have publish a new paper on genetic variation in Irish perennial ryegrass in collaboration with Susanne Barth Teagasc, Oak Park Carlow.

This study assessed the genetic diversity in 928 individuals from 40 diploid populations of Lolium perenne using nuclear simple sequence repeat markers, including 22 accessions of Irish ecotypes, seven European ecotypes and 11 released varieties. High levels of allelic and genetic diversity were determined, with intra-population variation accounting for the majority of the variation. The majority of the accessions deviated from Hardy–Weinberg equilibrium and had relatively high inbreeding coefficients. Two major gene pools of ecotypic accessions were defined by unweighted pair group method with arithmetic mean (UPGMA) and PCA analyses. One of these two gene pools accounted for two-thirds of the ecotypes and included most of the current Irish and Northern Irish breeding materials and about half of the European ecotypes included in this study; these European ecotypes performed well under Irish selection conditions. Population structure and differentiation analyses using Structure analysis and analysis of molecular variance confirmed the results found in the UPGMA and PCA analyses. These results will be useful for breeders who wish to exploit specific pools from ecotype collections.

More details:

Posted: Nick Gray

Monday, December 7, 2015

COP-21 Paris - Open sessions

COP-21 Paris - All hot air or an agreement to save the world from a climate disaster?

The COP21 conference is currently taking place in Le Bourget France with the aim to achieve a legally binding and universal agreement on climate to keep global warming below 2 degrees.  You are invited to hear how the negotiations are going and for you to have your say during some open sessions organized by Professor Mike Jones. The Global Room in the Watts Building is booked for two sessions the first is today from 5-7pm and the second on Thursday 10th December from 2-5pm. 

Sunday, December 6, 2015

Visualization of methane emissions from cattle

A new imaging technique, developed by a team led by  Dr Magnus  Gålfalk at the Linköping University in Sweden and described in Nature Climate Change, allows us to see for the first time where it is being generated.  The video shows methane emissions (shown in purple and green) escaping from a vent in barn of housing 18 cows. This is a major step forward in our management of greenhouse gas emissions from landfill, agriculture, wastewater treatment and any other potential source of the gas.

 Find out more about methane at: