Field Evaluation Of The Bio-Efficacy Of Three Brands Of Pyrethroid-Based Mosquito Coils Against Anopheles Gambiae Sensu Lato, A Malaria Vector, At Pokuase In The Ga West District Of Greater A

ABSTRACT

As a result of the increasing demand for the use of mosquito coils in Ghana, as a means of personal protection against Anopheles gambiae sensu lato, it was important to evaluate the effectiveness of three selected mosquito coils under field conditions and also determine the resistance status of Anopheles gambiae sensu stricto against pyrethroid-based mosquito coils. Three bands of pyrethroid-based mosquito coils; Angel Jumbo coil®, Lord Insecticide antimosquito coils® and Heaven Jumbo coil®, were therefore evaluated at Pokuase, Ga district, in Greater Accra Region of Ghana. The human landing catch (HLC) technique was used in a Latin square design to collect indoor biting mosquitoes from three different rooms, each treated with the different brands of mosquito coils and a fourth room with no coil as the control room. Collection from each room was replicated four times for each of the different brands of the mosquito coil. Species identification of mosquitoes was done using morphological characteristics, PCR and Hha1 restriction digest. A total of 935 Anopheles gambiae sensu lato were collected from rooms treated with the different coils as follows; 27 % (250), 16 % (150), 22 % (204) and 35 % (331) from rooms treated with Angel Jumbo coil®, Lord Insecticide antimosquito coils®, Heaven Jumbo coil® and control (no coil) respectively. The population of indoor biting mosquitoes from the treated rooms were significantly (P = 0.006) reduced in comparison with those from the control rooms. A percentage repellency of 26.9 %, 33.6 %, 51.4 % and 0 % was provided by Angel Jumbo coil®, Lord Insecticide antimosquito coils®, Heaven Jumbo coil® and control (no coil) respectively. The one hundred (100) An. gambiae s.l. examined were all identified as An. gambiae s.s., and consisted of 97 % S molecular forms, 2 % M forms and 1 % M/S hybrid. High level of resistance against the three pyrethroid-based coils was however observed because of the detection of the kdr gene in 98 % of the An. gambiae s.s. that were examined. The research findings, therefore, suggest that the tested coils cannot provide full protection against the malaria vector when used alone in areas where pyrethroid resistance has been developed by the mosquito vectors.