Currently I've been using these to deal with fungus gnats in my indoor plants; they are quite effective, just put one in my watering can, keep the watering can full so it can steep, and water as normal. It kills the larvae in the same way and after about a month I had no more fungus gnat problem (after trying many other things with no success)
I do wonder about the eventual mosquito adaption to this if it is employed on a large scale though.
This bacterial strain was discovered in 1976, but has been in the environment for a long time. Resistance should have already emerged?
"As a toxic mechanism, cry proteins bind to specific receptors on the membranes of mid-gut (epithelial) cells of the targeted pests, resulting in their rupture. Other organisms (including humans, other animals and non-targeted insects) that lack the appropriate receptors in their gut cannot be affected by the cry protein, and therefore are not affected by Bt."
Edit: "Spores and crystalline insecticidal proteins produced by B. thuringiensis have been used to control insect pests since the 1920s and are often applied as liquid sprays and donut pellets."
It does exist in nature all over, but it generally isn't in such a high concentration. Its like releasing 1,000 goats in your backyard. Even if your backyard could support a few goats, it will certainly be destroyed by 1,000 of them.
Bacillus thuringiensis is the most used pesticide in existence and has been for nearly a century. We’ve sprayed it everywhere in huge quantities, including on pretty much anything labeled “organic.”
What I really want to know is how do I CULTURE Bacillus thuringiensis, sure its available readily on the web as a pesticide, but only at very high prices for anything beyond a small hobby garden; -what if I have an acre of crops to treat? ~20 usd a pound for a spray bottle liquid solution is not even remotely acceptable.
You can look up how to culture it in the academic research but not only is it relatively hard, culturing Bt isn't enough to turn it into an effective pesticide. Bt is a soil microbe and sticking it on a regular agar plate guarantees it will be outcompeted by contaminants so culturing it requires sterile lab conditions and expensive lab equipment. You're going to need a full blown fume hood with active ventilation just to handle the initial samples and that's the bare minimum. Chances are you'll need a sterilized glove box and commercial off the shelf bioreactor.
The end product is produced in large submersion fermentation tanks where the bacteria is first grown, then then forced to sporulate and allowed to ferment which produces the Cry/Cyt toxin crystals within the spores. Going through these phases requires precise control over nutrients, pH, agitation, and electron acceptors. Even activating the spores to create the inoculum and begin the reproductive cycle is nontrivial because of how sterile everything needs to be.
This is a confusing analogy because it's more like releasing 1,000 goats then wondering why they don't have an effect.
My non-SME answer to this thread is:
1) 100 years is not that long in evolutionary terms;
2) cropland is large but not all land;
3) evolution is complex;
4) resistance is actually already observed in some species.
