> Chris, and anyone else curious about those "worms"
>
> Now here's a topic I can sink my teeth into since I spent my
> dissertation looking at these critters, and am still working on this
> fascinating system. There are three species of dipterans (flies and their
> relatives) that form a symbiotic partnership with S. purpurea. The pitcher
> plant mosquito (Wyeomyia smithii), a small, black midge (Metriocnemus
> knabi) and a sarcophagid fly (Blaesoxipha fletcher - I think the name on
> this one was recently changed) all lay their eggs in pitchers and, to the
> best of anyone's knowledge, nowhere else.
> The midge larvae are thin, white "worms" and
> range from tiny 1 mm long beasties at hatching to about 1 cm long or a
> little more just before they pupate. They feed on the dead prey as well
> and are normally found, often in very large numbers, down in the bottom of
> the pitcher.
That's them! Exactly as you describe. I've cut open some dying
pitchers and found them hiding in the detritus at the base in large
quantity.
> activities of the fly and midge larvae. There are also protozoa, algae,
> rotifers, cladocerans, several species of mites, and occasional nematodes
> that can be found in the pitcher fluid. None are used by the pitcher
> directly for food. Insects that fall into S. purpurea pitchers simply
> drown, and since these critters are all aquatic species, theyare not harmed
> and live quite happily in the pitcher fluid. Some like the midge larvae
> and the mites also appear to migrate from old pitchers to new ones. The
> mosquito larvae and fly larvae do not.
Yes, I often see them flying from one pitcher to the next in search
of a healthy, new pitcher full of water which they can lay their eggs in.
>
> Most of the controlled experiments indicate that the activities of
> these insect larvae benefit the plant by speeding up physical breakdown of
> prey and increasing bacterial degradation rates. This then helps get the
> nitrogen and phosphorous to the plant more efficiently. While there is
> good evidence to support an obligate relationship on the part of the
> insects, it is not known however, just how strong the mutualism is from the
> plant's point of view. Plants whose leaves contain these insect larvae do
> appear to grow bigger and produce more pitchers, and there does appear to
> be an ether-soluble chemical attractant that the female mosquitoes home in
> on, but no one has really done the definitive studies to show co-evolution
> between the plants and its inhabitants.
I definately agree with this statement. My one S.purpurea which
was infested the most is the first one to show significant growth thus
far. I often find the worms in the bodies of the beetles that I feed
my plants.
>
> To answer your question, just leave them alone. They are part of the
> natural pitcher food web that helps the plant get its nutrients from its
> prey. They're also really neat to observe. Oh, BTW, if your plants came
> from a northern population, the adult female mosquitoes do not bite so
> don't worry about itching and scratching. However, females from south
> populations do take a blood meal before they lay their second and
> subsequent clutches of eggs, so you might want to remove the pupae (little,
> brown, comma-shaped, wiggly things that float near the top) as they form.
Now that I see the results of leaving them alone, they do seem
to benefit the plant. I will leave them alone because they sort of form
a natural ecosystem. The larvae help the growth of the plants while some
of the midges end up as Drosera food!
>
> There are some really good papers on this system. I could send you a
> bibliography if you're interested.
I'd be interested and would be glad to read more information
on these. Also, if you happen to know of some papers documenting the
species of zooplankton and phytoplankton which inhabit pitcher plants,
I'd be interested (more in my field!).
>
> Liane
>
> Liane Cochran-Stafira
> Dept. of Ecology and Evolution
> The University of Chicago
> 1101 East 57th Street
> Chicago, Illinois 60637-5415
> phone: 312-702-1930
> e-mail: lcochran@midway.uchicago.edu
Thanks for your help and everyone elses on this topic. It
seems that no matter what, people said to just leave them alone unless
they started eating the pitchers.
Chris Teichreb
Department of Biology
University of Regina
Regina, Saskatchewan, CANADA
E-mail: teichrch@Meena.CC.URegina.CA