RESUMEN
The nature and type of local indoor resting wall surfaces to certain level influences the residual bio-efficacy of insecticides used in indoor residual spraying programs. Knockdown and mortality effects of an organophosphate Actellic 300 CS and pyrethroid K-Othrine WG 250 insecticides on the field-collected Culex quinquefasciatus were assessed bimonthly from July to November 2014, using World Health Organization (WHO) cones bioassay test. Knockdown and mortality rates were subjected to statistical analysis using χ2 and Student t tests. Result of the bioassay test on C quinquefasciatus showed that plywood surfaces had the best residual knockdown activity of Actellic 300 CS with knockdown rate above the WHO-recommended threshold limit of ≥95% for 30 days after treatment. This was followed by mud surface with knockdown rates ≥95% threshold limit 15 days (97%) after treatment. The lowest knockdown rates of less than 95% were observed on cement surface throughout the assessment period. However, the knockdown rates of mosquitoes on deltamethrin WG 250-treated cement and plywood surfaces were 100% and ≥95%, respectively, at 30 days after treatment. But the knockdown activity was below the recommended threshold limit on mud surface during the 17 weeks trial. Knockdown activities varied significantly (p < .05), and it is a function of exposure periods, different surfaces, and insecticide formulations. The 24-hour mortality rates of Actellic 300 CS and K-Othrine WG 250 at 120 days after treatment were 83.6% and 86.7%, and 80% and 83.3%, on plywood and cement surfaces, respectively. A maximum residual period of 75 and 45 days were recorded for Actellic 300 CS and K-Othrine WG 250, respectively, on mud surface. Both Actellic 300 CS and K-Othrine 250 WG were highly effective against Culex mosquito. The extended residual activity of p-methyl CS compared with deltamethrin WG 250 makes it a suitable alternative insecticide against pyrethroid-resistant mosquitoes in Southwest Nigeria.
RESUMEN
Nigeria has a high burden of vector borne diseases such as malaria and lymphatic filariasis (LF). This study aimed to determine the species composition of mosquitoes in Ibadan, Southwest Nigeria as well as determine their role in malaria and LF transmission. Adult mosquitoes were collected by Pyrethrum Spray Catch (PSC) and identified and graded according to their abdominal conditions. The mosquitoes were dissected to determine the parity status and to check for microfilariae of Wuchereria bancrofti. The presence of circumsporozoite protein of Plasmodium falciparum was examined using ELISA. A total of 1600 mosquitoes were collected of which 31 (1.9%) were Anopheles gambiae s.l. while 1756 (98%) were Culex sp. None of the mosquitoes examined was positive for Plasmodium falciparum and Wuchereria bancrofti. The lack of adequate sanitary conditions in the area could be responsible for the large number of mosquitoes collected. Health education could help in sensitizing the inhabitants.
