STUDIES ON THE DISSIPATION OF DIFLUBENZURON AND METHOPRENE FROM SHALLOW PRAIRIE POOLS

Abstract A series of sod-lined pools were constructed and used to monitor repeated applications of diflubenzuron as Dimilin WP-25 and mefhoprene as Altosid SR-10. Diflubenzuron and methoprene "disappeared" rapidly from the pool water as determined by bioassays using Aedes aegypti (L.) (Culicidae) larvae and by gas-liquid chromatography (GLC). Chemical assays for a diflubenzuron derivative were positive for several days; bioassay indicated the presence of diflubenzuron (or at least growth regulator activity) at levels toxic to mosquito larvae for up to 16 days. In contrast methoprene "fell" below GLC detection within 2 days although biological activity persisted for approximately a week after treatment. Neither parent compound should cause a long-term persistence hazard when used for mosquito control in Canadian prairie waters.