Abstract
The potential of the leaf extracts of Dodonaea viscosa Jacq. as termiticide on tunneling and midgut enzyme activities of Odontotermes obesus (Ramb.) (Termitidae: Isoptera) was evaluated in the present studies. In the preliminary bioassays, leaf extracts in polar and non-polar solvents were mixed in the soil at 1, 5 and 10% concentrations and their effect on mortality (LT) and tunnel length (mm) was determined. The toxic fraction following gel filtration was analysed for kaempferol by HPLC. The effect of standard kaempferol, gel fraction, crude leaf extract and chlorpyrifos was ascertained on tunnel length and enzyme systems in the gut of the termite species. n-Hexane crude leaf extract of D. viscosa was the most toxic registering minimum LT50 (104.41, 95.53 and 66.68 hours) and tunnel length (63.00, 36.33 and 16.67 mm), respectively at 1, 5 and 10% concentrations. Gel filtrated fraction No. 3 had significantly lowest LT50 (58.70, 33.96 and 15.94 h) corresponding to 1, 5 and 10% concentrations. The presence of kaempferol in gel filtrated fraction matched with peak of its standard in HPLC system. Interaction of effect of kaempferol, gel filtrated fraction, n-Hexane crude leaf extract and chlorpyrifos at their respective concentrations was non-significant but significantly different from their parallel control treatments. A significant decrease (p<0.05) in the activities of esterases, proteases and cellulases in the gut of termite workers after exposure to kaempferol, gel filtrated fraction, n-Hexane crude leaf extract treatments at different concentrations was observed. The activity of esterases in the gut was reduced in chlorpyrifos exposed termite worker, whereas proteases and cellulases in these workers remained nonsignificant with their control treatments. From these studies, it is concluded that kaempferol in n-Hexane extract of D. viscosa can be effective in the development of baiting system against the termites. (C) 2015 Friends Science Publishers