Any way to multiply Bti (Mosquito Dunks) before applying?

Curious if there's any way to breed/multiply the concentration of BTi from mosquito dunks before applying?

Currently I've got 3 jugs sitting with some crumbled up dunks to let them dissolve a bit and activate. In cases like AACT where you can add some type of 'food source' and get them to multiply this led me to pondering if the same can be done for BTi.

Not sure what the 'food source' would be in this case or how long / to what value it would be to attempt to do this.

Is it just the toxin or toxin plus bacteria?

If theres inactive bacteria you should be able to culture it up to a higher concentration. Not exactly easy. Likely very tricky-open air contamination. Then the need to have a 400x microscope and cytometer to quantify etc. Youd be bubbling blind really lol. Predator nematodes work well indoors. Fairly cheap and usually get 3-4 treatment for gnats. In a week youd see much much less gnats flying and less dead ones as the larvae get eaten.
FYI-the gnats can develop tolerance to BTI wirh longterm use. I use BTI over winter indoors on moms and dep plants. I use BTI 3 times in a row, giving a real good soak (for this I pamper and make a compost or worm casts extract as the base for my BTI drops ). Then using neem cake (not oil) extract for two treatments, and with or instead use pyganic once. And once outside the gnats go away.

I've looked into it. Here's some of the information I've come across.

So far my usual approach is to use neem in my mix which has usually helped eliminate/prevent but I have some media sitting in the garage and though I had some loose landscape cloth covering the totes I was still seeing some gnats here & there. As I'm planning to use it sometime in the next week or two this is a proactive treatment to get it better under control before I incorporate that batch.

Definitely a fan of using neem for IPM. I also usually use Captain Jack's Deadbug Brew when preparing new batches.

NewGrower2011 said:

Curious if there's any way to breed/multiply the concentration of BTi from mosquito dunks before applying?

Currently I've got 3 jugs sitting with some crumbled up dunks to let them dissolve a bit and activate. In cases like AACT where you can add some type of 'food source' and get them to multiply this led me to pondering if the same can be done for BTi.

Not sure what the 'food source' would be in this case or how long / to what value it would be to attempt to do this.

Click to expand...

You can probably use the same substrate as the dunks themselves. I would try putting a puck in a glass jar with water and about 30% honey to see if the bacteria start to inoculate the solution.

Then use that serum to inoculate, I bet any grain would do the trick in terms of inoculation. A sterile substrate is very crucial. Bacteria cultures simply need an organic carbon source to grow ie. sugars fats and amino acids.

Pressure cooker is a mycologist best friend, don't pressure cook liquid serums. Honey need to be sterile but not start to caramelize the sugars.

I just put it on the stove and heat to boilng point and then put aside. Boil with the double boiler principle. Cheers!