EVALUATION OF UNORTHODOX PREPARATIONS AND THEIR COMPARATIVE EFFICACY RELATIVE TO ORTHODOX INSECTICIDES AGAINST HOUSEHOLD INSECTS IN LAGOS

Abstract

Various insecticides including industrially compounded orthodox and mixed-up or single concentrate unorthodox (Otapiapia) formulations are used for controlling household insects in Lagos. Empirical information on the use of these formulations by Lagos residents and their efficacy is scanty. This study was consequently conducted to determine the use of unorthodox (Otapiapia) and orthodox formulations in Alimosho Local Government Area (LGA), Lagos and evaluate their efficacy against Anopheles gambiae, Musca domestica and Periplaneta americana using standard laboratory bioassays. For Otapiapia use, 150 structured questionnaires were administered to Alimosho LGA residents and the Otapiapia available in markets within the LGA were purchased to identify those used as insecticides. Unsexed Anopheles gambiae (0 – 2 d), M. domestica (0 – 3 d) and P. americana (adult) were exposed to various concentrations of selected Otapiapia (GO-90) or each of 13 orthodox formulations in standard air-tight glass cages. The LC₅₀ values of each test formulation were computed. The results show that 72 % of respondents use Otapiapia instead of orthodox formulations because it is cheaper and effective, and most respondents use Sniper (35.30 %) and GO-90 (15.30 %). Based on computed 15 min-LC₅₀ values, GO-90 was the most effective of all test formulations against An. gambiae (10.72 µlL^-1) and M. domestica (15.51 µlL^-1) while Baygon demonstrated higher efficacy against P. americana (13.42 µlL^-1) relative to other formulations.  The GC-MS analyses show that the major constituents in GO-90 by volume are Naphthalene (19.03 %), Cyclododecane (11.48 %) and Tetradecane (10.34 %). Test unorthodox formulations showed comparable efficacy relative to orthodox insecticides.