ABSTRACT
Flindersine, an alkaloid isolated from Toddalia asiatica, was evaluated for their antifeedant, larvicidal and growth inhibitory activities against Helicoverpa armigera, Spodoptera litura and larvicidal activity against vector mosquitoes Anopheles stephensi and Culex quinquefasciatus. For this, leaf disc no choice method was used for agricultural pests; larvicidal activity was tested on second and fourth instar larvae for mosquitoes at different concentrations. Flindersine showed antifeedant, larvicidal and growth inhibitory activities against H. armigera and S. litura and larvicidal activity against vector mosquitoes An. stephensi and Cx. quinquefasciatus. It showed high regression (R2) values of 0.91 and 0.87 against H. armigera and S. litura, respectively for antifeedant activity. Flindersine exhibited more than 65% larvicidal activity against both the pests with LC50 values of 443.04 and 568.88 ppm and R2 values of 0.87 and 0.90 against H. armigera and S. litura, respectively. The larval and pupal duration of tested insects increased to more than five days at 1000 ppm when compared with the control. The adult emergence was reduced when the concentration of flindersine was increased. At 1000 ppm, no adult emergence was observed in both the pests. Flindersine exhibited 100% larvicidal activity against both the tested mosquitoes at 20 ppm concentration, which showed LC50 values of 2.90, 4.19, 1.68 and 2.71 ppm for 2nd and 4th instar larvae of Cx. quinquefasciatus and An. Stephensi, respectively. High regression values were observed for antifeedant, larvicidal and growth inhibitory activities. Flindersine could be used to develop an ecofriendly pesticide formulation to control the agricultural pests and vector mosquitoes.
ABSTRACT
Larvicidal activity of pectolinaringenin from Clerodendrum phlomidis was evaluated against Anopheles stephensi and antifeedant, larvicidal and growth inhibitory activities were evaluated against Earias vittella. Pectolinaringenin exhibited larvicidal activity of 100 and 98.24% against 2nd and 4th instar larvae of Anopheles stephensi at 5ppm concentration. It exhibited LC50 values of 0.35 and 0.55 ppm for 2nd and 4th instar larvae, respectively. At 100 ppm concentration, pectolinaringenin exhibited maximum antifeedant activity of 74.00% and larvicidal activity of 89.98%. The LC50 values were 36.2 and 10.23 ppm for antifeedant and larvicidal, respectively. The compound completely prevented the adult emergence at 50 and 100 ppm concentrations. This is the first report of pectolinaringenin from C. phlomidis evaluated against An. stephensi and E. vittella. The results suggested that the pectolinaringenin from C. philomidis could be used to develop a new botanical formulation to manage vector mosquitoes and agricultural pests.
ABSTRACT
Twelve fractions from chloroform extract of Clerodendrum phlomidis and 5,7-dihydroxy- 4',6-dimethoxy-flavone (pectolinaringenin) were evaluated against Helicoverpa armigera. Maximum antifeedant (89.41%), larvicidal (83.77%) and ovicidal (69.25%) activities were observed in fraction 5. The least LC50 value for antifeedant (178.09 ppm) and larvicidal (198.23 ppm) were observed in fraction 5. No adult emergence was recorded in fractions 4-6 at 1000 ppm. The oviposition deterrent activity was 100% in fraction 5 at all the concentrations. Pectolinaringenin recorded maximum antifeedant (74.68%) and larvicidal (81.11%) activities at 100 ppm; it completely prevented the adult emergence of H. armigera at 100 ppm. Maximum ovicidal activity at 100 ppm concentration was 67.95%. The oviposition deterrent activity was 100% in 100 and 50 ppm concentrations. C. phlomidis could be effectively used to develop a new formulation to control the economically important pests.