Mosquito-larvicidal efficacy of the extract of Musca domestica maggots against Culex pipiens (Diptera: culidae), an important vector of Filariasis
The intolerably high burdens of mosquito-borne diseases will be reduced sustainably through the development of integral eco-friendly alternative insecticides of natural products origin. The need to broaden the global search for such insecticidal lead-agents, especially , those that will be less vulnerable to resistance, was the reason why this bio-assay study was carried out to test Musca domestica maggots against 4th instar larvae of the mosquito Culex pipiens pipiens. The larvicidal bio-assay followed standard World Health Organisation‟s protocols for testing the susceptibility of mosquitoes to larvicides. Larvicidal tests were carried out in a series of extract concentrations ranging from 0.25-4.50 mg/ml, in distilled and tap water media. The results showed that maggot extract possesses significant (P<0.05) larvicidal activities against the mosquito species, in a way akin to those reported for potent plant extracts. The larvicidal activities of the extract was dose dependent; and extract induced significantly higher larval mortality in tap water bio-assay medium than distilled water, except in the 0.25 mg/ml concentration treatment, where the reverse was the case. While, 100% larval mortality was recorded in extract concentration of 2.50 mg/ml in tap water, it took 4.50 mg/ml to kill all exposed larvae in distilled water bio-assay media. The LC50 values of the extract ranged significantly (P<0.05) from 1.57 mg/ml in tap water to 2.26 mg/ml in distilled water. The LC90 equivalents were 2.14 mg/ml and 3.47 mg/ml, respectively. These results suggest that insects may be at-least as promising as the botanicals in our search for eco-friend alternative insecticides.
Key words: Bio-assay media, Insect metabolites, Insecticides, Larval mortality, Lethal Concentration and susceptibility.