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ABSTRACT
Acetone extracts of Solenostemma argel and Argemone mexicana leaves were tested against 2nd and 4th instar larvae of Culex quinquefasciatus and Anopheles arabiensis mosquitoes. Five concentrations (276, 138, 69, 34.5 and 17.25 ppm) were used from each extract. Highest larval mortality was found in leaf extract of S. argel for both mosquito species. LC^sub 50^ and LC^sub 90^ values of S. argel against 2nd and 4th instar larvae of Culex were 84.7, 123.4, and 34.2, 93.2 ppm 72 hrs post treatment, respectively. Respective LC^sub 50^ and LC^sub 90^ were 49.6, 230.6, and 84.7, 122.1 ppm for Anopheles. The LC^sub 50^ and LC^sub 90^ values of A. mexicana leaf extract were 87.9, 149.8, and 105.8, 780.1 ppm, against 2nd and 4th instar larvae of Culex, respectively. While respective values in Anopheles larvae were 100.3, 180, and 71, 161.1 ppm. These results suggest that the two plant extracts have promising larvicidal action against larvae of the tested mosquito species.
Key words: Larvicidal activity, Argemone mexicana, Solenostemma argel, acetone extracts, Anopheles arabiensis, Culex quinquefasciatus.
INTRODUCTION
Mosquitoes are the most important group of insects as vectors of human and animal diseases such as malaria, filariasis, yellow fever, dengue fever, Japanese encephalitis, etc. (Centers for Disease Control and Prevention, 2007). Mosquito-transmitted diseases remain a major cause for loss of human life; worldwide about 3.3 billion people - half of the world's populations are at risk of malaria. About 250 million malaria cases and nearly one million deaths have been recorded annually (WHO, 2009 and 2010).
Malaria is a significant health problem in Sudan, affecting 52% of outpatients and accounting for 9% of all hospitals deaths. Malaria in Sudan was mainly transmitted by the mosquito species Anopheles arabiensis (Federal Ministry of Health, 2006). Culex quinquefasciatus is a vector of lymphatic filariasis, widely distributed in tropical zones with around 120 million people infected worldwide and 44 million people having common chronic manifestation (Bernhard et al., 2003).
More than 2000 plant species are known to possess some insecticidal properties (Klocke, 1989). Plant products or plant-derived compounds are promising alternatives and preferred in comparison to synthetic insecticides in controlling insect pests of medical importance (WHO, 1992 and Abdul Rahuman et al., 2008). Those compounds fall into several groups, including toxins, anti-feedants, repellents,...