Synergistic Combinations of Flower and Leaf Extract Activities of C. cinerariifolium , E. camaldulensis and N. tabaccum Outweigh the Activities of Antagonistic Combinations

Crude leaf extracts of C. cinerariifolium (Cc), Eucalyptus camaldulensis (Ec) and Nicotiana tabaccum (Nt) were individually and in combination tested for their synergistic and antagonistic activities against third instar larvae of Anopheles gambiae s. s. Giles. Six different solvents were used for the extraction of oils from the flowers and leaves of the three plants namely ethanol, methanol, Dicholoromethane (DCM), hexane, ethyl acetate and aqueous. The larval mortality of the third instar larvae of An. gambiae s. s. Giles was observed on 24 hours exposure separately in control using 50, 100, 150, 200, 250, and 300 ppm of crude flower and leaf extract concentrations. For the individual tests, all extracts of the plants showed good larvicidal activity. Thirty treatments were carried out to determine synergism and antagonism on extract combination ratio of 1: 1 (v/v) (i. e 100 ppm: 100 ppm) and it was observed that 16 extract combinations exhibited synergistic activities (SFgreater than1) and 10 activities indicated antagonistic activities (SF1