Evaluation of nymphicidal and ovicidal effect of a seaweed, Padina pavonica (Linn.) (Phaeophyceae) on cotton pest, Dysdercus cingulatus (Fab.)

Impact of brown seaweed, Padina pavonica (Linn.) chloroform, and benzene extracts were evaluated against an economically important cotton pest, Dysdercus cingulatus (Fab.) (Pyrrhocoridae). The result reveled that between the two solvents, benzene extracts of P. pavonica caused more nymphal mortality. It reduce D. cingulatus egg hatchability than chloroform extract. Benzene extract also reduced the survival rate of D. cingulatus eggs from 53.33 to 0.00 per cent for 0.025 to 0.4% concentration of P. pavonica benzene extract respectively. P. pavonica 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 P. pavonica possess both nymphicidal and ovicidal activity. It can be utilized for the management of sucking pests of cotton and other crops.