Aquaponics Digest - Tue 03/10/98 




Message   1: Re fungus gnats
             from Gail Hall 

Message   2: Re: Component Ratio
             from Ian Beaver 


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Subject: Re fungus gnats
From:    Gail Hall 
Date:    Tue, 10 Mar 98 15:01:52 -0700

Gail wrote
>I have successfully used a product called Gnatrol (Bt israelensis) a 
>liquid formulation of Bt from Abbott Labs similar to VectorBac that is 
>also highly selective against the larvae of greenhouse fungus gnats. The 
>liquid is diluted with water and sprayed onto breeding areas where it is 
>fed upon by the larvae, causing death within 24 hours. 

Paula asked
Do you have a list of ingredients for this product that you could
post? I'm hoping someone will have an opinion based on that for it's
acceptability for use in systems involving fish specifically.

Gail answers
Bt israelensis is listed in my IFM catalog as an organic pest control. 
The Bacillus thuringiensis is "the most widely used microbial insecticid. 
Bts are a higly selective family of bacterial insecticides. Three major 
varieties have been identified and are available for agricultural use. Bt 
kurstaki, for pest caterpillars of all moths and butterflies; Bt 
israelensis, effective against the larval stages of fungus gnats, 
blackflies and mosquitos and Bt Sand Diego, effective against young 
larvae of Colorado potato beetle and the Elm leaf beetle. All of the Bts 
are only effective against larvae and are stomach poisons that must be 
ingested. Bt is exempt from tolerance limits on all raw agricultural 
commodities." Dipel is a brand name for Bt kurstaki and commonly 
available to gardeners.

The VectBac mentioned in the first listing is another brand of Bt 
israelensis, similar to Gnatrol.

My assumption from the catalog description is that the only ingredient is 
the bacterial agent. For more information you can call 1 800 332-3179 and 
talk to the owner of the company, Phil Unterschuetz. He has been very 
helpful to me with my questions.

Gail Hall


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Subject: Re: Component Ratio
From:    Ian Beaver 
Date:    Wed, 11 Mar 1998 15:17:51 +1300

Hi

Ive got a question regarding ratio's of fish to garden beds. If one has
an ornamental tank, that is comparatively lightly stocked with fish,
compared to if you where growing larger fish for food production, what
ratios would you use then. It seems to me that the ratios would need to
be expressed in volume of bed to weight of fish.

Another question that comes to mind regards fertility levels. If one
wanted to grow gross feeding plants such as tomatoes, is it practical to
obtain sufficient levels of nutrition to feed these plants. There is a
huge difference between the nutritional levels for lettuce than
tomatoes. Any thoughts on this.

Regards

Ian Beaver
Northland, New Zealand

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