Insecticidal effectiveness of naphthalene and its combination with kerosene against the emergence of Aedes aegypti in Ika North East, LGA, Delta State, Nigeria

Abstract

Despite the substantial progress achieved in the search of nonchemical alternatives to insecticidal larviciding on mosquitoes, more work is still required to unravel the potency of viable substances in order to attend to several pest and disease problems. Insecticidal effectiveness of naphthalene and its combination with kerosene against the emergence of Ae. aegypti in Ika North East, LGA, Delta State, Nigeria was assessed. Immature stages of Ae. aegypti were collected and left to acclimatize for 6 h in standard laboratory conditions. Naphthalene measured in 2 g and its combinations with kerosene in 50:50 were emptied in 400 ml, 200 ml and 100 ml of water which resulted in 0.005%, 0.01% and 0.02% concentrations respectively. Water alone served as control for the experiment. Twenty third instar larvae and pupae were sorted into containers before exposure to treatments. Experiment was done in triplicates and observed for 10, 15, 20, 30, 40, 50, 60, and 80 min coinciding with WHO protocol for Aedes exposure. Mortality was highest in larvae exposed to 0.02% kerosene and naphthalene, and was also high in 0.02% naphthalene. Lowest mortality was recorded in pupae exposed to 0.005% of naphthalene. Significant differences in toxicity was recorded (p < 0.05). Mortality increased with time in larvae and pupae. Highest mortality in pupae and larvae was recorded in 0.02% kerosene and naphthalene mixture at 80 min post exposure time respectively. LC50 and LC95 of naphthalene exposed to Aedes larvae and pupae was between 0.002 and 0.018% and 0.021–0.051% respectively. Similarly, for naphthalene with kerosene was between 0.002 and 0.007%, and 0.015–0.035%. Pupae exposed to 0.005% naphthalene had more adult emergence than in others and the differences were significant (p < 0.05). Field trial is required with optimum concentrations.