BIO-POTENTIALOFAGREENMARINEALGAE Chaetomorpha antennina (Boryde Saint-Vincent) Kutzing) ON THE LIFE CYCLE OF A POLYPHAGOUS INSECT Spodoptera litura (Fabricius)

Chaetomorpha antennina (Bory de Saint-Vincent) Kützing, a green marine alga collected from the Puducherry coast, India, was investigated for its biological activity against the polyphagous pest Spodoptera litura Fabricius. Acetone, methanol, and chloroform extracts of C. antennina at concentrations of 1, 3, 10, 30, 50, 70, and 100 μl/ml were tested against homogeneous third-instar larvae of S. litura under a completely randomized design. The effects were compared with solvent control and untreated control. Treated larvae were observed for larval mortality, pupal mortality, adult emergence, and repellent and antifeedant activities, and the data were recorded systematically. The larvicidal activity of acetone, methanol, and chloroform extracts of C. antennina showed no significant effect up to 24 h of treatment. Among the treatments, the acetone extract exhibited the highest larval mortality (66.67%), followed by methanol and chloroform extracts. Although larval mortality increased gradually across treatments, pupation varied significantly, and pupal-toadult conversion was comparatively lower in all treatments. Adult emergence data revealed that the solvent effect of C. antennina (10%) resulted in pupal-to-adult conversion ratios of 1:0.54, 1:0.40, and 1:0.50 for acetone, methanol, and chloroform extracts, respectively, whereas the control and solvent control recorded a higher ratio of 1:0.92.