Environmental aspects of field trials with pyrethroids to eradicate tsetse fly in nigeria

Abstract Permethrin, cypermethrin, and decamethrin were applied in field trials to eradicate tsetse flies in the northern Guinea savanna zone in Nigeria. Aerial application of ultra-low-volume formulations of cypermethrin (150 g ai/ha) and decamethrin (30 g ai/ha) were nearly or completely successful. Biological environmental monitoring showed no effects on vertebrate populations. Acute mortality occurred in many terrestrial and aquatic arthropods, notably water beetles and crustaceans. Malaise trap catches showed significantly reduced abundance of flying insects for at least 10 days after spraying. Shrimps and mayfly larvae disappeared from river benthos samples after spraying, but were found again in samples taken 1 year later. The severe reduction in aquatic arthropod abundance may represent a hazard to fish populations through reduced food supply but this could not be assessed at the current pilot scale of spraying operations.