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Re: Aquatic Plants Digest V4 #706
Dwight wrote:
> Thus, whenever a leaf broke
> the surface....aphids!
>
> I have a terrarium for emersed growth Ludwigia acuata, grandelosia and a
> few others... no aphids. Yet the terrarium is side - by - side w/ an
> opened top tank who's emersed growth got hit w/ aphids. The terrarium is
> opened to the air w/ a 1/4" crack that allows any aphid to enter. It
> seemed so obvious that high leavels of Co2 gas in the terrarium kills all
> the aphids! Talk about a natural insecticide!
I reply:
Perhaps this "obvious" reason for a lack of aphids is correct, but has
this hypothesis been tested? If someone had asked me what the obvious anti-
aphid agent in the example was, I would have guessed "higher humidity," or
perhaps "airborne aphids are few and far between and 96% tank coverage
typically excludes enough to prevent formation of a population."
A very preliminary test of your hypothesis would be to add aphids to the
terrarium onto a plant of identical species and see how they do.
Pierre Gagne
Kensington, MD