MORE ON MOSQUITOS

By: Derek Butcher

based on research by John Catlan

July 1999

This all started when the late Carol Johnson mentioned that certain Australian hybrids (namely Neoregelia 'Charm') had bad smells. (See BSIJ #5 1997 page 230.) Let me remind you that Australians (hybrids or not) do have a shower every day! Anyway, this started off John Catlan who hails from Jacobs Well just south of Brisbane, Queensland.

He blames the smell on infusoria which are at the bottom of the food chain and which we expect to find in the water in our Bromeliads. Infusoria breed on rotting materials and I am not sure if the smell comes from the infusoria or what attracts them! John tells me that infusoria have only a short life span and it is the dead ones you can smell, so the more breeding, the more deaths, and the more smell!

Anyway, John worked for some 4 years in Indoor Plant Hire and Neoregelias were good colourful plants to use. However, at flowering time, especially in low light situations, the plants would smell and complaints were numerous, vocal, and demanding! John considered the problem to be too much water in the cup which submerged the petals, which were busy producing nectar, thus producing a decaying mess which fed the infusoria. Whatever the reason, it does suggest you should keep the centre cup of Neoregelias on the dry side at flowering time, especially if indoors and not "my cup floweth over"! Needless to say we don't have this problem in Adelaide where our Summers are sun and more sun. Infusoria like shady conditions!

Amongst his many other jobs John spent some 8 years breeding Tropical fish and the type he bred really loved and needed mosquito larvae. John says Bromeliads are a dead loss as far as mosquito breeders are concerned, but he just had to get his mosquito larvae. I quote "Broms are hopeless when it comes to mosquitos if there is algae in the cups there are never any wrigglers! If there is old water in the Brom cup there are never any wrigglers! The only time I have found wrigglers is when the water in the Brom has been dumped, or evaporated and fresh water added, even then the results should be better numbers." John goes on to hypothesise that perhaps Bromeliads have the ability to absorb nutrient from this water or exude some hormone by some means not yet known to Science.

The story goes that he found a dead (? squashed) toad (? cane) which was placed in a drum with a brick to keep it on the bottom then water was added. Something was there which is not usually found in Bromeliads, namely one squashed toad, but the infusoria loved it and multiplied. The wrigglers were regularly captured with a fine net and fed to the fishies. (John called them fish fry!)

So we know that infusoria prefer darker areas and mosquitos follow.

Mention should be made here to Robert Smythe's experiments with "Mitsubishi logos" and other creatures that seem to control mosquito larvae. (See separate article named 'Bromeliads and Mosquitos'). Robert mentioned to me that he couldn't understand how a small "Mitsubishi logo" could affect large mosquito larvae. Could it be that they ate the infusoria before the mosquito larvae got a chance therefore starving them out? Something to consider.

Let us now move from the darkness to the light and where in light conditions algae thrives, given the right conditions . We know that algae tends to smother out mosquito larvae.

John likes watching Science programmes on T.V. just in case he might learn something new. On the programme "Beyond 2000" he saw where a farmer had solved an age long problem he had in one of his streams. He had accidentally dropped a bale of hay in the stream and had left it there because a wet bale of hay is not much use to anyone. The farmer noticed the following year that the algae had disappeared. Research seems to have proved that hay somehow breaks the food chain and that hay from Barley is a preferred option. So far it appears no-one knows why. Algae produced mainly in light conditions will reduce the mosquito population but if hay breaks the food chain including infusoria then we may see some odd looking Neoregelias.

If you are aware of any other research into the goings on in Bromeliad tanks, especially with regard to Mosquitos please let us know.


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