Ovicidal activity of factors from Calendula officinalis L. extracts against a generalist herbivore, Spodoptera litura Fab. (Lepidoptera: Noctuidae)

Abstract

The leaf and flower extracts of the Calendula officinalis prepared using various solvents of varying concentrations served as test solutions for bioassays against the eggs of Spodoptera litura F. The promising results of reduced egg hatchability (98.02%) at a 5% concentration of chloroform leaf extract during our preliminary bioassays with topical application to the eggs facilitated further fractionation of extract with different combinations of solvents that yielded eleven fractions. Following this was the conduction of bioassays with each of these fractions (0.1% concentration) against eggs of different age groups (freshly laid, 1-day and 2-day old), which revealed fractions F-2 and F-9 to show poor egg hatchability (14.6±8.71%, 21.3±8.78%; 31.67±6.03%, 45.3±1.78% and 38.33±3.58%, 45.3±1.78%) respectively among all age groups consistently followed by other fractions and controls. The fractions were subjected to UV, 1HNMR, 13CNMR, IR and EI Mass spectroscopy and their spectral data confirmed the probable compounds to be α-antiarin and Oryzanol-A in the fractions F-2 and F-9 respectively. Incidentally, both being known ones procured from other plant sources, this happens to be the first report not only to detect their presence in Calendula but also to report their ovicidal activity against Spodoptera litura. The results from the present investigation clearly advocate that the active fractions or the isolated compounds could probably be used to develop a novel pesticidal formulation to control economically important agricultural pests.