Sunday, January 1, 2012

The Clivia Food Web: Part I

Natal Lily (Clivia hybrid) in flower 
Bulbs are one of the Home Bug Gardener's obsessions. Not that most bulbs are especially useful plants for promoting insect conservation in the Aspen Parkland of Alberta, but anticipation of the blooming of the 2000 or so spring bulbs that inhabit my yard does help fight off the winter gloom. The most spectacular of my bulbs, however, blooms in the Fall - a Clivia hybrid given to us by a friend. Or rather I should say bloomed in the Fall, which it did in 2010. Last Autumn, though, they could barely muster a few yellowed and sickly leaves. Still I brought the pot inside when the frosts came (Natal Lily hails from Southern Africa) and hoped for the best.
Rove Beetle from Clivia pot - Anotylus insecatus
When a plant starts looking sickly there is often an arthropod or a microbe to blame (or an incompetent gardener) and when one finds an insect associated with a sick plant it is easy to assume the worst. The small (4.5 mm long) rove beetle above, Anotylus insecatus (Gravenhorst, 1806), is both an invasive alien insect and associated with rotting bulbs - so finding it in my Clivia pot was not encouraging. However, the beetle is probably a predator of bulb maggots and other pests (see Campbell & Tomlin 1983) and not a pest itself. Still, as Fall became Winter and no new growth or flower stalks appeared, something would seem to be rotten.
Clivia pot worms, insects, springtails, and mites
A few weeks ago I repotted the Clivia - and yes, half the bulbs were rotting - and sent the soil and slimy bulbs off to the University for extraction. All you need to extract arthropods from soil is an incandescent light bulb, a funnel, a screen, and a small container that fits the stem of the funnel. From these simple ingredients you can assemble a Berlese Funnel (aka Tullgren Funnel) and start learning about the animals that live in soil. As the light bulb dries out the soil, the animals follow the moisture gradient down, pass through the screen, and tumble into the collecting container. Berlese funnels work best for arthropods, but some worms and snails will come through too. The Clivia pot turned out to have a lot of inhabitants (see above): an earthworm (large worm at left above); another kind of rove beetle (black and about 4 mm long), as yet unidentified; several pot worms (Enchytraeidae - the small white worms mid-picture); and a host of springtails and mites. The good news: lots of harmless soil animals and no bulb maggots; the bad news: lots of bulb mites.

Unfortunately, most of the mites from the extraction were the notorious Bulb Mite Rhizoglyphus robini Claparède, 1869. Bulb mites do best in cold, wet weather - like last summer - and once a bulb is colonized, they are difficult to eliminate. But - the second most abundant mite in this extraction was a predatory mite in the genus Gaeolaelaps (also called Hypoaspis). Izabela Lesna and her colleagues in the Netherlands have shown that Gaeolaelaps aculeifer (Canestrini, 1884) can be an effective biological control agent of bulb mites. If only I had been a bit lazier and waited to repot the bulbs until later in the New Year, the problem may have solved itself. Still, I now have the makings of a map of the feeding relationships inside my former pot of Clivia - a food web. That sounds like a good project for the New Year and a chance to contribute to the Wildlife in Our Homes Project.
Mystery Rove Beetle from Clivia pot soil
Campbell JM, Tomlin AD. 1983. The First Record of the Palearctic Species Anotylus insecatus (Gravenhorst) (Coleoptera:Staphylinidae) from North America.The Coleopterists Bulletin 37(4): 309-313.

Lesna I, Sabelis M, Conijn C. 1996. Biological Control of the Bulb Mite, Rhizoglyphus robini, by the Predatory Mite, Hypoaspis aculeifer, on Lilies: Predator-Prey Interactions at Various Spatial Scales. Journal of Applied Ecology 33(2 ): 369-376


  1. Is there perhaps a name for that process of arthropods extraction ?

  2. Hi Wong Chun Xing:

    The Berlese Funnel is a behavioural extraction system. Small arthropods have a relatively large surface to volume ratio and find it difficult to retain water. Those that live in soil - where the relative humidity is high (typically >95%) - tend to lack the adaptations for retaining water found in arboreal arthropods and closely track humidity gradients.

    In the Tullgren-modified Berlese Funnel (technically the correct name) an incandescent light bulb is used to produce heat to dry the sample (Berlese used a radiator-like assemblage of tubes with hot water). Drying establishes a steep humidity gradient from the top to the bottom of the sample. The animals follow the gradient and end up tumbling out of the sample at the bottom, into the funnel, and into the collecting vial. Thus, this funnel system uses the normal humidity-seeking behaviours of the animals to extract them. Conversely, if the animals are inactive (e.g. estivating, moulting), then they will not be extracted.

  3. Hi,

    I have a plant that I bought 5 years ago when it was a tiny bulblet, which I thought was an amaryllis/hippeastrum. Until 6 weeks ago when it bloomed, *exactly* like the photo of your clivia hybrid. I think we must have similar clivia hybrids. Do you have more info on it? When i did a search for natal lilies, none of them looked like the flower you have pictured here, so it must be crossed with something else. Any info would be greatly appreciated!!!

  4. Hi,

    Five years ago someone gave me a tiny bulb that she told me was an amaryllis. Six weeks ago it bloomed and the flowets looked *exactly* like your picture of your clivia hybrid! Do you have more info on this plant? Mine has a bulb and leaves very much like amaryllis/hippeastrum does, and offsets like crazy. It also has 3 bloom spikes with 8 blooms on each. Any info you have would be great!

    1. Hi Juliet,
      Clivia is in the Amaryllidaceae, so if your bulb is a Clvia, your friends were correct in a loose sense. Clivia is named for a Duchess of Northumberland whose maiden name was Clive. They don't tolerate frost, but do tolerate shade, drying out, and general abuse, so they make good container plants. There are four species and countless hybrids and varieties. I think mine is derived from Clivia miniata (aka Bush Lily, Flame Lily, Forest Lily, September Lily, etc.), because the other species have pendant, tubular flowers.

      You might check out the Clivia Society registry:



  5. Thanks Dave! I've contacted the Clivia Society registry, hopefully they can help solve this mystery!

  6. It turns out my plant is a Cyrtanthus elatus. So it's not a clivia at all! It also goes by the name "Scarborough Lily" or "George Lily".