Blocking activity of <i>Aloysia citrodora</i>Leaf Extract on the Sporogonic Development of <i>Plasmodium falciparum</i> field isolate against <i>Anopheles gambiae</i> S.L. (Culicidae: Diptera)

Abstract

Mosquito ingests blood consisting of male and female gametocytes during a blood meal on
the human host. The gametocytes fertilize and undergo division and produce infective sporo- zoites ready for transmission in the human host. This study is aimed at developing simple and effective technique of preventing malaria through spraying of an effective dose of Aloysia citrodora leaf extract in an environment in order to prevent the sporozoite development (sporo-gony) in the mosquito. Using membrane feeding method, female Anopheles mosquito (Anoph-eles gambiae) was directly fed with blood infected with Plasmodium falciparum. Transmission was assessed using 150 mosquitoes’ samples (test:100; control:50). A. citrodora leaf extract concentration was prepared in three-fold dilution ranging from 300, 150, and 75. One hundred and fifty (150) mosquitoes was assigned to each of the four test groups and assayed by one of the three concentrations of the extract. The mosquitoes were dissected after 7-9 days to deter- mine infection (Oocyst carriage). The result for oocyst after treatment with extract, while the control group shows the presence of Oocysts. Large number of sporozoite were present in mosquitoes fed with infected (treated) blood meal with ethyl acetate extract of A. citrodora extract 98 (19.7 ±24.9) when compared to control with 45 (8.9±9.6) number of oocyst. This result show ethyl acetate has low blocking effect on oocyst development. 62 number of oocysts presence out of 107 dissected mosquitoes with average mean of 57.9±12.9) when compared with control (untreated) with 28 (24.7±70.0) respectively. In conclusion, the possibility of using A.
citrodora as bio-insecticide against Anopheles gambiae was established. The approach will be of
great benefit to the poor populace by reducing the financial burden on the patients as well as reduce exposure and excessive spread of harmful insecticide chemicals in the environment.