Abstract
Spodoptera litura is a serious cosmopolitan polyphagous pest of vegetables as well as pulse crops. Indiscriminate use of chemical pesticides has caused harm not only to non-target organisms, but have developed resistance against this target insect pest which has diverted the use of synthetic pesticides to botanical ones. In the present investigation, the crude solvent extracts of leaves belonging to diverse families were screened and tested for their antifeedant activity against Spodoptera litura by leaf disc no-choice bioassay method for 24, 48 and 72 hours. All leaf extracts tested showed varying degrees of antifeedant activity and maximum feeding deterrence was expressed by the hexane extracts of Vernonia cinerea (73.44%); Cassia fistula (76.48%); and Vernonia cinerea (78.69%) after 24, 48 and 72 hours of exposure respectively. Overall results indicated that, among the solvents tested, it was the hexane which should pronounced activity followed by diethyl ether; and among the plants tested, Cassia fistula, Jatropha curcas, Piper longum, Tephrosia purpurea and Vernonia cinerea were found to be promising with more prominence exhibited by Cassia fistula since all its extracts showed activity above 50%. Antifeedants mode of action were directed at the taste cells and the mechanism of action of antifeedants through which feeding inhibition was established in the present study was by inhibition of feeding through sensory perception, by the phytocompounds of the plant extracts providing an unpalatable taste to insects. Therefore, further studies on isolation and identification of the active antifeedant principle present in the promising plants will emerge as an additional tool for the management of Spodoptera litura.
Keywords