Aha! A check of FAA Tail # database (yes, FAA, it's a US tail #) shows it's a Cessna A188B. It IS used for crop dusting...Not sure what kind of crops they dust in Boa Vista, but I did see some big truck driving around town at night with a big sprayer on the back. It seemed to be spraying bug spray or something all over the place. Must be a Dengue Fever control measure.