Activity of triflumuron on Culex pipiens pipiens (Diptera : Culicidae) andimpacts on two larvivorous non-target species

Alsystin 48% EC, the common name of triflumuron, was first tested on fourth instar larvae of Culex pipiens pipiens L. (Diptera: Culicidae). Treatment was made at different concentrations ranging from 16 to 79 ng/l on earlier larvae for 24 h. The compound caused morphological aberrations and increase d the duration of larval development. In addition, it resulted in an inhibi tion of adult emergence. The histological study conducted on sternal integu ment during the 4th instar larvae, showed that Alsystin (16 and 79 ng/l) ca used a significant reduction in the thickness of both larval and pupal cuti cles compared to controls. in a second series of experiments, the impact of Alsystin, applied for 24h at a 52,8 ng/l, was evaluated on two mosquito la rvivorous species : a fish, Gambusia affinis (Cyprinodontiforme: Poeciliida e), and a mite, Piona constricta (Acari : Hydrachnidae). Results showed tha t treatment reduced the number of juveniles per brood in G. affinis and the survivorship in P. constricta. Thus, Alsystin prevent molting in C.pipiens pipiens larvae by interfering with cuticle deposition confirming the prima ry mode of action of the benzoylphenylurea insecticides. It also exhibited a slight toxicity in mosquitofish.