Didn’t Antigua do something like this years ago for arriving flights? I only remember it happening once or twice and in honesty, I think we deplaned and they then sprayed the interior of the plane before we or the new passengers were allowed back on board. I don’t recall them actually spraying the interior but I do remember the smell after we boarded and it wasn’t great. I would say this was very early 80s or there about and then AA gave Antigua it’s own flight. It was a long, long time ago and I think it might have been for insect control but that, too, has a question mark to it.