I didn't take a lot of time with the research, but it does sound like there are several species of other insects that prey on whiteflies. Ladybugs apparently are a predator, though a fairly insignificant one. Not knowing which of these species bugs might be indigenous to Pierre's area, and being somewhat hesitant about introduced insect species, I didn't mention them.

Perhaps, Pierre, you could research beneficial insects that prey on whitefly larva and nymphs, and then plant flowers that would attract the beneficials? While I don't think the evidence is that beneficials are sufficient control, they will help. And from what I understand, you need all the help you can get with whiteflies.