We used to see a lot of toads. But now that you mention it, I haven't seen a toad in months. Maybe the ducks wiped out the toads.
I was thinking to go out myself very early in the morning (4am) to try and hand pick them. I wonder if I could remove enough to make a difference?
The internet suggested beneficial nematodes and predatory wasps, but I can't get my hands on those things here in rural Kenya. I also found a brief mention of neem extract, but I have only one baby neem tree. Time to plant a few more, I think.
The government is suggesting chemicals, of course. But from what I read the chemicals compound the problem, as they also kill the beneficial insects that provide natural biological controls. So when the next set of eggs hatch after spraying, there is nothing left to resist the worms.

this being the rainy season, I doubt the effectiveness of sprays, as they will likely wash off before the worms feed.