Insect growth regulatory activity of Thevetia nerifolia Juss. against Spodoptera litura (Fab.)

Screening for insect growth regulatory activity (IGR) of Thevetia nerifolia leaf extracts were evaluated against Spodoptera litura (Fab.). Methanol extract of leaves provided 53.8 % larval mortality, 29.6 % pupation and 22.3 % adult emergence at 2.5 % concentration level. The extract was further subfractioned with solvents of different polarity in search of better IGR activity and chloroform extract was found to be most active in terms of larval mortality (27.5-61.5 %), pupation (28.4-60.2 %) and adult emergence (19.8-52.8 %). GI50 of the extract was recorded to be 3.02 %. Activity was attributed to the glycosides present in the extract.