Evaluation of the Efficacy of Wormatak® (Teflubenzuron and Cypermethrin) Against Anopheles Gambiae Sensu Lato and Its Impact on Non-Target Organisms

Abstract

This study investigated the efficacy of WormAtak® against Anopheles gambiae s.l. larvae, pupae and adults (Diptera: Culicidae) collected from Opeibea and Madina in Ghana and its effect on three non-target organisms under laboratory conditions. Anopheles gambiae s.l. and the non-target organisms were all exposed to five concentrations of WormAtak® (1.86 μM, 3.71 μM, 5.57 μM, 7.42 μM and 9.28 μM). Mortality was recorded for a period of 72 hours for Anopheles gambiae s.l. F1 third instar larvae. Mortality readings for Anopheles gambiae s.l. pupae and female adults were taken after 9 hours exposure and 24 hour recovery periods respectively. The results of the experiments indicated that WormAtak® was effective against the developmental stages of Anopheles gambiae s.l., with the pupal stages proving more susceptible. WormAtak® concentration of 1.86 μM caused mortalities of 87%, 89% and 95% in Anopheles gambiae s.l. F1 third instar larvae from Opeibea, Madina and the susceptible strain respectively after 72 hours. Whilst that of 9.28 μM caused mortalities of 98%, 100% and 100% in Anopheles gambiae s.l. F1 third instar larvae from Opeibea, Madina and the susceptible strain respectively after 72 hours. All pupae in all concentrations of WormAtak® from the three populations could not emerge into adults and 100% mortality was obtained in less than 24 hours in all treatments. WormAtak® also had a lethal effect on the female adults of Anopheles gambiae s.l. WormAtak® showed detrimental effects on the non-target organisms with 100% mortality occurring in all concentrations of WormAtak® on Poecilia reticulata, Bufo sp. and Physa waterloti after 24 hours. WormAtak® can provide a rapid and effective way for controlling mosquito larvae, pupae and adults but must be carefully introduced in environmentally sensitive areas due to its relatively broad spectrum on non-target organisms.