Farinosyn, a novel insect growth regulator from the silver fern <i>Cheilanthes farinosa</i> Kaulf

Abstract

Bioassay-guided fractionation of the methanolic extract of silver fern (<i>Cheilanthes farinosa</i>)<i> </i>results in the isolation of a novel insect growth regulator, farinosyn whose structure has been established by spectroscopic analysis. It has shown morphogenetic effect against the Ameri can bollworm of cotton, <i>Helicoverpa</i> <i>armigera </i>(Hubner), when fed at two different doses against fourth (25 and 50 μ<i>g</i>)<i> </i>and fifth instar (50 and 100 μ<i>g</i>)<i> </i>larvae causing reduction in larval weight (31-71%), delay in moulting (6-9 days), mortality up to 100% and reduction in fecundity (88- 100%).