Chemical Control of Leptoconops spinosifrons in the Seychelles

Abstract

Abstract The man-biting midge Leptoconops spinosifrons (Diptera: Ceratopogonidae) is a major nuisance on many beaches in Seychelles and, with a developing tourist industry, control is required. Malathion, applied weekly as a spray at 1000 g a.i./ha or twice a week with u.l.v. equipment at 1750 g a.i./ha, was not effective; this finding was supported by laboratory studies. DDT exercised control for five months when applied as a spray at 2200 g a.i./ha, at 1100 g a.i./ha control lasted less than one month. DDT residues were detected in Donax cuneatus, an intertidal filter-feeding mollusc, 15 months after the last application. Diazinon, applied as a spray at 6000 g a.i./ha produced good control for five months and applied at 600 g a.i./ha every two weeks gave excellent control. The importance of correlating times of spraying with the lunar tide cycle was confirmed.