Evaluation of nymphicidal and ovicidal effect of a seaweed, <i style="">Padina pavonica</i> (Linn.) (Phaeophyceae) on cotton pest, <i style="">Dysdercus cingulatus </i>(Fab.)

Abstract

Impact of brown seaweed, <i>Padina pavonica</i> (Linn.) chloroform, and benzene extracts were evaluated against an economically important cotton pest, <i style="">Dysdercus cingulatus</i> (Fab.) (Pyrrhocoridae). The result reveled that between the two solvents, benzene extracts of <i>P. pavonica</i> caused more nymphal mortality. It reduce <i style="">D. cingulatus</i> egg hatchability<i style=""> </i>than chloroform extract. Benzene extract also reduced the survival rate of <i>D. cingulatus</i> eggs from 53.33 to 0.00 per cent for 0.025 to 0.4% concentration of <i>P. pavonica </i>benzene extract<i> </i>respectively. <i>P. pavonica</i> extracts also significantly reduced the total body protein (22 to 39%) and DNA (27 to 30%) content. Presence of saponin, steroids and phenolic compounds in the extract might be the reason for these activities. It is concluded that<i> P. pavonica</i> possess<i> </i>both nymphicidal and ovicidal activity. It can be utilized for the management of sucking pests of cotton and other crops.