Starting new trial: Btk vs Bg (M)

Doing things differently in some ways this time. Only two groups per treatment, not four. Groups consist of ten snails each as before, but they get a much bigger volume of artificial pondwater - 150% more - that might encourage reproductive activity, as we were close to critical crowding level last time. Not testing 1000ppm in chow this time, as that dose is ridiculously high for insects. Testing 1ppm, 10, and 100. And of course 0, my hero. Using a different strain of Btk, just because it was available in much more concentrated form than the highly diluted Dipel Dust. Monterey Bt is kurstaki strain SA-12. I don't know anything about the two strains except that they both kill caterpillars especially, by comparison to non-kurstaki Bt (e.g. israelensis, which targets dipterans, or maybe just mosquitoes). Planning to count not just egg masses but embryos this time, and also see how well some of the embryos develop. Also planning to test the reversibility of the treatment: if Bt-treated snails stop laying eggs, do they start up again when returned to non-poison food? I got it started today. Before selecting snails for groups, I first had to pick about thirty egg masses off snail shells. Yes, they oviposit on each other. I'm wondering if the 'female' in a mating pair tends to lay eggs on the shell of her 'male' preferentially? or just on whomever happens to pass by. Well, that's another project.

 

experimental setup

 

Eighty-three snails. I used eighty of them.

 

Here are the ~30 egg masses I peeled off shells, and the peeling tool.

 

Here is the poison. It's liquid, and nearly 100% active ingredient.