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4 December 2019
www.thevillagenews.co.za
MY ENVIRONMENT
Myrmecochory – What do ants have to do with seed dispersal? By Dr Anina Lee
#alloveroverberg All over the Overberg, The Village NEWS covers the many beautiful towns, villages and hamlets with interesting articles. Greyton is one of these quaint villages, nestling peacefully in a hollow of the majestic Riviersonderend Mountain range. Go online to read some of these stories about Greyton and its many wonderful residents
Richard and his chocolate factory thevillagenews.co.za/richard-and-his-chocolate-factory/ What kind of magic does it take to turn a young South African accountant into a chocolatier? Greyton’s Richard von Geusau would be the one to ask.
Greyton Genadendal offers classics for all thevillagenews.co.za/greyton-genadendal-offers-classics-for-all/ Every year when the vineyards turn to gold and the chilly evenings draw in, like homing pigeons, lovers of good music know that it is time to head for the Greyton Genadendal ‘Classics for All’ Festival. Handfuls of talent: Greyton’s modest master craftswoman thevillagenews.co.za/handfuls-of-talent-greytons-modest-master-craftswoman/ When Sharon Peddie, Greyton’s talented chef/woodcarver/goldsmith was a little girl, her accountant father whose hobby was carpentry, let her help him at his bench, so she grew up with a chisel in one hand and a hammer in the other. Later, she added a metal saw and an egg whisk. Creativity flows through her fingertips. www.pressreader.com www.issuu.com/dwaal
083 700 3319 theagency@thevillagenews.co.za
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hat a magnificent word! It’s a word not even my addled memory forgets because I say it over and over just for the sound of it. Why, you may ask, is myrmecochory even in my vocabulary? Not so strange. It means “carried by ants” and hence the dispersal of seeds and fruits by ants. Many plants employ this method of spreading their seeds, most notably fynbos plants in the protea family. I cannot possibly describe this interesting phenomenon better than Peter Slingsby: Myrmecochory (literally ‘ant borne’) is a process by which certain plants ensure the survival of their species after a fire. The seeds or fruits of literally hundreds of fynbos plants have a fleshy covering or attachment that acts as an ‘elaiosome’ or ant-attractant. When the seeds fall to the ground certain ant species, especially ants of the genus Anoplolepis (Pugnacious ants) rush to the seeds, attracted by pheromone-imitating scents. The ants sink their jaws into the soft, fleshy covering and tug the seeds into their nests, where the sweet-tasting reward is consumed. The hard, smooth nuts that are left cannot be gripped by the ants’ tiny mandibles, and so remain buried in their nests, safe from fire and animal predators. The seeds’ longevity is also enhanced by the anti-bacterial and fungicidal substances which the ants secrete to keep their crowded nests healthy. The fruits of Mimetes, Leucospermum, Paranomus and several other Proteaceous genera, all the Buchus or Rutaceae, many legumes and scores of other genera are involved in this important ecological process. The re-emergence of Mimetes stokoei, thought to be extinct for nearly 50 years, dramatically demonstrates the success of myrmecochory, especially for large-seeded plants. The seed does not have to travel at all; it drops straight to the ground and is buried by ants within a few minutes in the same optimal soil as its parent. These
plants need to produce fewer seeds, because the chance of successful regeneration after fire is much less random. There is a safe underground seed store and not all the seeds germinate after each fire. A very short interval between two fires may have no effect. Finally, we now know that such seeds can remain viable for long periods – probably a century or longer. Tiny populations of rare species can survive in specialised habitats, apparently indefinitely – which is good news for the future of fynbos diversity.
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Mimetes stokoei illustrates the critical importance of myrmecochory. The species was thought to be extinct in the wild but ‘miraculously’ appeared again after a fire. The seeds had been safely stored underground by ants until conditions were right for germination. But there is a big problem lurking underground. Invasive ants such as the Argentine ant – Linepithema humile – massively disrupt these processes. They not only completely displace most of the indigenous ants involved in myrmecochory, but they don’t bury the affected seeds. They merely eat the elaiosomes off, leaving the seed above ground and unprotected, at the mercy of rodents, birds and fire. How do we recognise this invader? Argentine ants are small, shiny, dark brown ants about 2.5 mm long. They are the guys that invade our houses and move in single file along ant tracks in huge numbers. They are the ant species most commonly found around human habitation. As the name suggests, Argentine ants come from Argentina. They probably reached Cape Town in 1900 during the South African War in a shipment of fodder imported from Argentina by the British army to feed their horses. They have now spread around the world and live on all continents except Antarctica. Preliminary studies suggest that if the spread of these ants into wild habitats is not checked, the future of thousands of fynbos plant species could be at risk. Myrmecochory is the sole survival strategy employed by the majority of our showy and iconic Proteaceae, and many other fynbos families too. What can we do to help? Firstly we have to get to know our ants to be able to distinguish indigenous from alien invasive species. Citizen-science projects could add enormously to our understanding of the extent of invasions.
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1. Argentine ant (Linepithema humile). GRAPHIC: Peter Slingsby 2. Extremely rare Mimetes stokoei. PHOTO: antsofthecape.blogspot.com 3. Small pugnacious ant (Anoplolepis steingroeverii) with seed of Mimetes cucullatus. GRAPHIC: Peter Slingsby It is possible to poison Argentine ant colonies without affecting the surrounding species. An “ant trap” can be made that is so constructed that only the small Argentine ants can get into the trap where food laced with ant poison is located. They carry the poison back to the nest to feed the queens (yes, many queens in one colony), thereby poisoning the queens that lay the eggs. So on your next foray into the veld, observe the ants and what they do there. It could be either good or very bad. Sources: www.antsofthecape.blogspot.com Veld and Flora December 2014 Vol 100 (4) http://planet.botany.uwc.ac.za/
whale coast
CONSERVTION ensuring wonders never cease
WITH WHALE COAST CONSERVATION 10,11 & 12 December 2019 Environmental Education Room Grotto Pavilion (next to car park) Open 09:30 - 13:00 Guided Educational Walkabouts @ 10:00 and 11:30 All welcome, entry FREE
