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Potential Toxicity and Insect Growth Regulator Activity of Red Algal Seaweeds against a Polyphagous Pest, Spodoptera litura (Fab.)

Department of Entomology, Annamalai University, Annamalai Nagar-608 002 (Tamil Nadu), India
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(Received : July 19, 2019; Accepted : September 21, 2019)


Toxicity studies were conducted in the Department of Entomology, Faculty of Agriculture, Annamalai University, India during 2018 with four red algal seaweeds viz., Gracilaria corticata J. Agardh, Gracilaria opuntia Durairathnam, Hypnea panosa J. Agardh and Jania rubens (Linnaeus) J. V. Lamouroux native of Rameswaram coast against Spodoptera litura (Fab.) was a polypahagous pest in agriculture. Shade-dried seaweeds were powdered in a blender and from which the treatment concentrations were prepared. The
concentrations used were 1, 3, 5, 7, 10 and 20% along with control. The free choice experiment was laid under CRD with three replications. Treated leaves were fed to four hours starved third instar larva (homogenous culture) and after treatment larval mortality data were collected for every 12 h and presented. Larval mortality data displayed that, among the tested seaweeds, G. corticata treated larva exhibited mortality at 36 h after treatment and gradually increased over time and at 72 h after treatment all the concentrations encountered 100% death, whereas in other seaweed treatments mortality initiated only at 72 h of treatment which showed the supremacy of the seaweed in exerting mortality of S. litura.
Key words : Red algal seaweed, toxicity, growth regulator, Spodoptera litura